%% This list of examples has been alphabetized. Please add your example in the proper place. Thanks!

[[quoteright:250:[[WesternAnimation/PinkyAndTheBrain http://static.tvtropes.org/pmwiki/pub/images/larryknox_997.PNG]]]]
[[caption-width-right:250:What do you mean, ''"Larry wasn't always in the show?"'']]

->'''Ada:''' You... knew each other?\\
'''The Dark Id (as Leon):''' Well, the script says I did, but hell if I've ever seen that guy before the cutscene just after the fight with Todd.
-->-- '''LetsPlay/TheDarkId's''' LetsPlay of ''VideoGame/ResidentEvil4''

A previously unmentioned character who suddenly appears without notice and who we are told was really there ''all along'' but just... off screen or something. It comes about because the writers want to introduce a new character, but don't want to come up with a complex introduction where everyone meets them and learns what they're like- it's just plain easier (and lazier) to pretend that everyone automatically knows them, and the relationship is ready-made. "Oh hey, that's my old rival!" "Oh, this is my brother/sister whom I've never told you about," etc.

In other words, this is a relative or a friend or even a rival whom we really should have met, or at least heard about before, since the other characters would have us believe they have been crewing the same starship, working on the same project or sitting on the other side of the same classroom for years.

This ''[[TropesAreTools can]]'' work if the character (and the actor) proves compelling enough for the audience to suspend their disbelief, or that it's possible nobody mentioned them "on-camera" before (like if the show is set in a school, and the character is a casual acquaintance of the others but hasn't done anything significant to the plot until now). It's also possible if there's an in-story reason for the character to have been incognito (perhaps they were a spy, or an escaped convict), and the character was there in plain sight all along, but disguised as one of the show's many extras. Among the most clumsy versions is the "Long-Lost Daughter/Son." This trope can be especially disruptive if the new addition [[StoryBreakerTeamUp doesn't fit the tone]] of the series.

A subversion of this trope can come into play when a newly-introduced character actually ''wasn't'' there before, but the characters believe they were due to FakeMemories or a CosmicRetcon.

Related to (no pun intended) LongLostUncleAesop, but while LongLostUncleAesop is usually a one-shot character to deliver AnAesop, Remember the New Guy is basically a new main character {{retcon}}ned out of thin air. (In fact, the term "Retroactive Continuity" was originally coined to describe ''this'' trope).

If the character is [[WeHardlyKnewYe going to be killed off straight away]], this trope can be used to turn him into a MauveShirt beforehand.

Compare CainAndAbelAndSeth, CousinOliver and NewNeighboursAsThePlotDemands. Can often occur in combination with SuspiciouslySimilarSubstitute, when an actor is no longer available and a new character is quickly brought in with minimal introduction to fill the role. Contrast ChuckCunninghamSyndrome, in which a character ''disappears'' with no explanation. When an adaptation takes steps to avert this, it's an EarlyBirdCameo.

!!Straight examples:


[[folder:Anime and Manga]]
* Orin the [[HighlyVisibleNinja Pink Ninja]] in ''Manga/AkazukinChacha'' is revealed later to have been in class the whole time, but ''clinging to the ceiling.''
* ''Anime/AngelBeats'': Every acquaintance of an NPC seems to have this trope, considering [[spoiler: how Yuri had a supposed friend when she was almost {{Brainwashed}} into becoming one]].
* Aoi Kuineda's primary circle of Red Tails from ''Manga/{{Beelzebub}}'' consisted of Nene, Yuka, Ryouko, and Chikai. Then, a random, never before mentioned purple haired member was inserted into the group, and treated as if she's been there from the very start.
* A particularly frustrating example occurs in ''Manga/BlackClover'', where in one arc Asta and Noelle meet up with a group of three mages, Fanzell, Dominante, and Mariella, in the Witches Forest Arc. Though they have never appeared in the manga before, Asta and Noelle are not only familiar with them, but have apparently already helped them escape from the Diamond kingdom, and even received trained with them. The characters were originally introduced in a light novel that serves as a side story to the manga, but it can be infuriating when the manga has flashbacks to events that never occurred in the manga, not only that, but it's nearly impossible to tell when exactly the events of the light novel took place relative to the manga.
* ''Manga/{{Bleach}}'':
** Uryuu Ishida is first introduced in Chapter 34 as Ichigo's classmate and the highest-scoring student in the entire grade, yet Orihime has to explain to Ichigo who he is while Tatsuki lampshades the RunningGag of Ichigo's careless forgetfulness. However, careful reading of earlier chapters reveals Ishida in the background of several panels, including Chapter 1's cover, and his father is mentioned in a throw-away line in Chapter 7, so Kubo [[TropesAreTools deliberately invoked]] this trope.
** A rather heartbreaking/nightmarish version of this occurs during the Fullbringer arc much later in the series: Shūkurō Tsukishima makes everyone think Ichigo has gone insane by using his powers to [[FakeMemories insert himself into their memories]], making them think he's a close friend and ally who helped them in their quests all the way back to the beginning of the series, so they have no idea why Ichigo is furious at and attacking Tsukishima.
* Shingo Aoi from ''Manga/CaptainTsubasa'' was introduced in the World Youth arc as a Tsubasa fanboy who went to say goodbye to him in the airport as he left to Brazil.
* One reason Ryo of ''Anime/DigimonTamers'' is seen as a CanonSue is this. Even if one takes into account his [[AllThereInTheManual huge backstory]] (that [[NoExportForYou most of the viewers outside of Japan never even got to see until later]]) that explains his presence, his sudden appearance still comes a bit out of left field even with the proper context.
* ''Manga/DragonBall'':
** Dr. Gero is a perfect example: he was a scientist that worked for the Red Ribbon Army and created the androids for them, including the previously seen Android 8, but he was never mentioned in the Red Ribbon Army Saga. It's only when he shows up in the Android Saga years later in-universe, all this time he was making more androids until he made ones that could defeat Goku and the others, and is also revealed that the whole time he was spying on the main characters with a hidden camera and collecting cells from them to create Cell. It even [[AdaptationInducedPlotHole creates a plot hole in the anime]], where Dr. Flappe was said to be the creator of Android 8 in the RR Saga, which was only addressed in a [[AllThereInTheManual supplemental book]] that states they both worked on it together.
** Speaking of, the villain of the video game ''VideoGame/DragonBallFighterz'' is a GodCreatedCanonForeigner named Android 21, who is stated to be ''another'' former Red Ribbon Army scientist.
** The God of Destruction Beerus from the movie ''[[Anime/DragonBallZBattleOfGods Battle of Gods]]'' is a semi-example. One of the strongest beings in the entire universe (in fact, the only one stronger is his attendant Whis), no one ever mentioned him until the movie, even though Kaio, the Kaioshins, Freeza, and Vegeta all knew about him, yet in the series they named many weaker people as "the strongest in the universe". Although this could also be explained by the fact that they were referring to the strongest "people". Beerus is a God and just like all the Kais, is not factored into mortal power rankings.
** ''Anime/DragonBallSuper'' introduces Bulma's older sister Tights; both Goku (who's known Bulma since they were kids) and Vegeta (her husband) react to this news with "You have a sister?!" Of course, the meta reason is that Tights is a CastTransplant from Toriyama's manga ''Manga/JacoTheGalacticPatrolman'', which was written almost 20 years after the ''Dragon Ball'' manga ended. Jaco himself could also count, since Bulma has known him since she was little but it apparently never came up in the intervening decades.
*** Tights late mentioning can be justified by Bulma's tendency of not talking much about her family to her friends, just as she never mentioned her parents in the first two arcs. Tights has also distant herself from her family for most of her life, so it's easy to forget her.
* In ''Manga/FairyTail'', Gildarts gets this treatment in the anime. It was supposed to end before he was introduced, so the five or so mentions of his name before the Edolas arc are cut out.
* Yoki and May in ''[[Manga/FullmetalAlchemist Fullmetal Alchemist: Brotherhood]]'' are this to viewers who haven't read the manga or watched the [[Anime/FullmetalAlchemist 2003 anime version]]. They cut the Youswell episode which serves as a proper introduction to Yoki, and May was also supposed to be introduced later in Youswell. To ''Brotherhood''-only viewers, Yoki and May are just two random people who join Scar because they somehow know of the Elric brothers, and Yoki wants revenge for some reason. Yoki's back story and desire for revenge are explained later in the show in a series of quick flashbacks. These flashbacks occur several episodes after Yoki is introduced however, still leaving people who had never read the manga or seen the 2003 anime thoroughly confused for a while. Hilariously, when Yoki actually meets them, Ed himself doesn't remember him at first, [[ButForMeItWasTuesday despite ruining his life.]]
* Padparadscha of ''Manga/LandOfTheLustrous'' is suddenly introduced in episode 11--Rutile, the doctor, had been working to resolve their chronic coma for much longer than the time-span of the series. The protagonist knew about this character the whole time (saying "I'm glad I [[LaserGuidedAmnesia didn't forget]] about Padparadscha"), but never mentioned them before this point.
* Queen Diamond in ''Anime/KaitouJoker''. She's Silver Heart's granddaughter and grew up alongside the main protagonist and his rival, but doesn't show up or even get ''mentioned'' until chapter 41.
* In ''Manga/LuckyStar'', when the cast starts their senior year, Kagami is approached by Misao and Ayano, noting that they are glad to be in Kagami's class again. Kagami then walks off, [[LampshadeHanging Misao notes their position as background characters]], and the two then become members of the regular cast. Misao did make a brief appearance prior to this, and she even had a line... [[TheOtherDarrin with a different voice actress]] than the one she had when she started showing up regularly. Ayano also made a brief, unnamed appearance as a participant in the sports festival before becoming official. In the manga, though, the two were at first ''unnamed'' and were only intended to be random classmates of Kagami's class. It was later when they were actually given names and personalities.
* ''Franchise/LyricalNanoha'':
** Most good characters from ''Anime/MagicalGirlLyricalNanohaStrikers'' have met the characters from previous seasons before. It's justified by the fact that there was a ten year TimeSkip. At that point, it would have been surprising if they ''didn't'' know new characters.
** Inverted with Corona Timil from ''Manga/MagicalGirlLyricalNanohaVivid'', who has been Vivio's friend since shortly after the ''[=StrikerS=]'' epilogue. While it is also played straight, Corona remembers characters from previous seasons, even in cases when she doesn't meet them again.
** Done with Thoma, the main character of ''Manga/MagicalRecordLyricalNanohaForce''. Something of an odd case, since he seems to have met everyone in the TimeSkip between ''Anime/MagicalGirlLyricalNanohaStrikers'' and ''Force''.
*** Touma's BelatedBackstory, presented in part via flashback chapters, shows that he first met Subaru (and through her, the rest of the Nakajima extended family) in the apparent aftermath of ''AudioPlay/StrikersSoundStageX''. It's also worth noting that outside of the Nakajima family (and [[HeterosexualLifePartners Teana]]), the other, more established main characters ''don't'' know Touma (at best, for instance, Nanoha knows ''of'' him), and they all introduce themselves properly once the circumstances allow for it.
* In ''Manga/MyMonsterSecret'', the two main characters first met Karen at chapter 60, yet it's revealed later that she's the StudentCouncilPresident of their school. In the next chapters it's shown that Nagisa (the ClassRepresentative) and Mikan (president of the news club) have known her since the start. Apparently, normal students are unaware of her existence, or that they even have a student council at all.
* ''Manga/{{Naruto}}'':
** Naruto already knows the members of Team 8 and 10 and is later shown interacting with some of them in flashbacks during his time at the academy even though they do not appear to be anywhere in the classroom in Chapter 1 or 3 of the manga, even in wider shots showing the entire classroom. Likewise, Sakura and Sasuke first appear as Naruto's classmates in Chapter 3, but are nowhere to be found in the classroom scenes in Chapter 1. Averted in the anime, where all of aforementioned classmates make brief {{Early Bird Cameo}}s in the respective episodes. Possibly a case of FridgeBrilliance; Naruto had failed the Graduation Exam twice already, so he might simply have been moved to another class that had not taken the exam yet. There are at least 10 teams of three Genin so there should be at least 30 new Genin but we barely see half that number in any scene.
** Karin who first appears later in the series is shown as a participant of the Chunin Exams from earlier in the series having first met Sasuke during the Forest of Death portion of the exams, yet she did not actually appear in chapters that originally depicted the Chunin Exams.
** Another example: the presence of Danzo Shimura and his organization "Root", only introduced as of Part II/''Shippuuden'', having largely affected the behind-the-scenes politics and histories of major characters. [[EnforcedTrope Which is, in-universe, what they precisely intended to be.]]
** [[spoiler:Hamura Ootsutsuki, the brother of the [[PhysicalGod Sage of the Six Paths, Hagoromo]] and inheritor of [[BigBad Kaguya's]] Byakugan. Not once has he ever been hinted at existing (in-universe reasoning is the Uchiha Tablet being modified), but since his introduction, he's been noted as helping Hagoromo defeat the Juubi, a feat originally seen as a solo act by Hagoromo.]]
** ''Manga/{{Boruto}}'' introduces a bunch of kids that weren't seen in ''Anime/BorutoNarutoTheMovie'', ''Manga/NarutoGaiden'', or the original DistantEpilogue. They however are good friends with Boruto during his Academy days. The episode showing [[spoiler:Naruto's inauguration]] short had new scenes added with some of them in it.
* ''Anime/{{Pokemon}}'':
** Since Episode 35 ("[[Recap/PokemonS1E35TheLegendOfDratini The Legend of Dratini]]") of ''Indigo League'' [[BannedEpisode was not aired outside of Japan and a couple other Asian countries]], the 30 Tauros Ash accidentally caught in that episode appear to come out of nowhere in "Showdown at the Po-ké Corral".
** During the ''Battle Frontier'' arc, which took place in Kanto (the setting of the first season), second- and third-generation Pokémon were portrayed as being indigenous to Kanto... even though no one seemed to know about them the first time around (barring an EarlyBirdCameo or two like Misty's Togepi, and even then the cameos were presented as one-of-a-kind in the region).
** Pokeathlons weren't in the original ''VideoGame/PokemonGoldAndSilver'', instead introduced in the remakes, which were released nearly ten years later. Despite this, Ash and Brock act like they had experience in the sport when Lyra mentions them in ''Diamond and Pearl''.
** Serena is supposedly one of Ash's ChildhoodFriends. Naturally, since her design is based on the default female player character from ''VideoGame/PokemonXAndY'', she first appeared in the anime arc based on said games and was never seen or mentioned prior. {{Downplayed|Trope}} in that Ash helped her out one day at summer camp and she clung to that memory; given that Ash has always been a FriendToAllLivingThings,[[note]][[BackportedDevelopment his cockiness in Kanto notwithstanding]]; the two tropes aren't ''mutually exclusive'', they're just hard to juxtapose,[[/note]] [[ButForMeItWasTuesday said memory didn't stand out for]] ''him'', though he ''does'' remember her as the "straw-hat girl" when she recalled that meeting.
* The ''Anime/PrettyCureAllStars'' movies inflict this whenever extra Cures show up between the last movie and the current ones. ''New Stage 3'' had this as a minor gag when Grell and Enyen go to confront the ''Anime/DokiDokiPrettyCure'' team and are bewildered at the sight of Aguri and she the same. It's only when Mana walks up that the make the connection.
* Ai Kaga of ''Manga/SayonaraZetsubouSensei'' first appears in the ''last'' episode of the first series. She explains that she hid away from the camera, believing that if she appeared it would drive down the ratings.
* Just as their western brethren, ''Franchise/{{Transformers}}'' anime can be guilty of this as well. ''Anime/TransformersArmada'' offers a baffling example, where the humongous Autobot Overload makes his grand intro by randomly rolling up in the middle of an episode to act as Optimus Prime's trailer. It's never explained where this guy came from, which is made even weirder by the fact that he's supposedly a small Mini-Con robot called Rollout who wears "Overload" as PoweredArmor. Despite that gathering these Mini-Cons was the main ''point'' of the series' first half, with ''many'' episodes being dedicated to [[GottaCatchThemAll finding one or two "regular" Mini-Cons]], here we have one that comes with his own set of gigantic armor and can look the regular robot cast in the eye, yet he's the one not to get an intro episode.
* Because of its episodic nature, this tends to happen in ''Manga/{{Uzumaki}}''. One notable example is when a chapter near the middle of the manga introduces Kirie's pregnant cousin, Keiko. Even though Kirie's clearly close with Keiko, this is the first time we ever hear of her.
* In the fourth season ''Anime/YuGiOhGX'', Yusuke Fujiwara uses the "false memory" variant on almost everyone (see below), but it's played straight when Fubuki remembers him. Fujiwara was his classmate and he was connected with the old Obelisk Dorm and Fubuki's disappearance prior to season 1.
* ''Anime/YuGiOh5Ds'' featured Kyosuke Kiryu and Crow Hogan, who were apparently always [[TrueCompanions best friends with the main characters]] despite not appearing in any of the flashbacks with Yusei and Jack in the past. Crow is particularly bizarre, since in prior episodes, Yusei was established as hopelessly scrounging for parts [[AfterTheEnd in Satellite]] to build a D-Wheel that even works, but Crow, also a Satellite resident in even worse economic straits, is introduced with a high-spec D-Wheel in perfect condition that can ''fly.''
** Crow's high-quality D-Wheel is later justified, since he inherited it from his late friend Robert Pearson, who was a luminary in building D-Wheels and he was even offered a job in Neo-Domino City.
* Parodied with Rise in ''Manga/YuruYuri''. She's supposedly been the head of the student council from day one, even though none of the four lead girls have ever seen her. To drive this home, a FlashBack shows that she was present at the group's [[BeachEpisode trip to the beach]], but stood just out of view of the camera.
* Not exactly a character, but the ''LightNovel/ACertainMagicalIndex'' movie ''Miracle of Endymion'' does this with the SpaceElevator Endymion. Lampshaded when Index sees the structure for the first time and asks what it is and where it came from. Touma pokes fun at her, comments that her PhotographicMemory must not be as perfect as she thought, and claims the structure has always been there. He has a flashback montage that shows the structure [[RetCon edited into]] the background of several important past scenes. Index gets really confused, as she is sure she's seeing it for the first time.
* Sabo from ''Manga/OnePiece''. We are made aware of the shared history of sworn brothers Luffy and Ace throughout the show. Even seeing some quick flashes of them sharing a ritual to become brothers. But when they finally show the full flashbacks of the two meeting and developing their relationship, we are suddenly introduced to a new character, their third sworn brother, Sabo. Even the previously mentioned flashback of their ritual suddenly had Sabo involved in it too. There was the '''very''' subtle hint in Ace's misspelled tattoo (ASCE, with the S crossed over), that was downright impossible to know what meant, and what we saw of the brother-making-ritual contained three cups - only with Sabo, the drinker of the third, never being shown.
* ''Manga/DetectiveConan'': The series tends to switch between this trope and ForgottenFirstMeeting. If it's the latter, the series provides hints that the main cast might have met the new person before. One example is Eri Kisaki who was never mentioned by Ran and Kogoro before her introduction and Shinichi/Conan has already forgotten how she looked like.

[[folder:Comic Books]]
* ''ComicBook/ArchieComicsSonicTheHedgehog'':
** Similar to the [[WesternAnimation/SonicSatAM show]]; Dulcy the Dragon was fitted in with nothing more then a small back-up story introduction which gave her backstory and essentially went "She's been part of the Freedom Fighters all this time! Honest!" Dulcy was later phased out of the comic, only appearing in the backgrounds in the last couple years and later not even those. From "remember" to "forgotten"? Post-[[CosmicRetcon Super Genesis Wave]], Dulcy has been reintroduced to the (extended) cast. As this was in a story arc that added several characters, and showed flashbacks to her introduction (in the past of the new universe) it was less jarring than the first time.
** Lampshaded example when Dr. Eggman meets a leader of one of his armies known as Axel the Water Buffalo. He's quick to say he recognizes him and recruits him in trying to get to the Death Egg II. Orbot's quick to point out that they've never seen him before and Eggman has already figured that out - he admits that he was too hasty in stopping Super Sonic's Chaos Control, and realizes that a lot of Mobius has been altered..
* ''ComicBook/AstroCity'' does this for essentially all of the superpowered characters. Because the series is written as if there is a longstanding continuity (which there isn't), most people are introduced in one issue and will have their origins explained many issues later, if at all.
* Baron von Blitzschlag is a minor example, created as a former Nazi supervillain now working as a research scientist for ''[[ComicBook/TheAvengers The Initiative]]''. He was supposed to have fought several World War II era superheroes, but he was never a particularly notable villain. Blitzshlag was [[WhatCouldHaveBeen originally meant to be Arnim Zola]], but since Creator/EdBrubaker was using the character in ''Captain America'', writer DanSlott [[CaptainErsatz created a new character to fill the same role.]]
* Creator/JephLoeb introduced a new ''Franchise/{{Batman}}'' character called Thomas Elliot. He was apparently a childhood friend of Bruce's, and Bruce holds him in incredibly high regard, and it's heavily implied that Thomas partly inspired Bruce's methods as Batman... Which is why we never heard of him before the story arc. This was (almost) an exact copy of a ''Franchise/{{Superman}}'' story [[ComicBook/TheDeathOfClarkKent just a few years before.]] During ''Comicbook/ZeroHour'', we were introduced to Kenny Braverman. ChildhoodFriends with the hero -- check. Been here all along -- check. Becomes a BigBad (Conduit) -- check. Drives our hero to the brink of madness -- check. Tries to kill our hero -- check.
* Happened ''twice'' to Creator/DCComics' ComicBook/BlackLightning. Creator/JuddWinick created an adult daughter for him called Thunder, with her existence {{handwave}}d away with a line saying that she'd mostly lived with her mother after her parents' divorce. Then, a few years later, Creator/GeoffJohns introduced a second daughter, Lightning, and this time there wasn't much effort put into reconciling the fact that she'd never been seen or mentioned before this.
* This is by now many years old, but the introduction of Comicbook/{{Cable}} happened this way too; right when he was introduced everyone was treating him as if he had always been around. Which, [[TimeyWimeyBall considering his backstory]], is either FridgeBrilliance or HilariousInHindsight.
* Isaiah Bradley, the black ComicBook/CaptainAmerica. He was introduced in 2003, but was retconned into having been active in Marvel's [[UsefulNotes/TheGoldenAgeOfComicBooks Golden Age]] during UsefulNotes/WorldWarII. He's supposedly a pillar of Marvel's black superhero community, and characters like ComicBook/{{Luke Cage|HeroForHire}} and ComicBook/BlackPanther are shown to be in awe of him.
** Golden Girl and the Human Top. Both of them were created in the 70's to add a little diversity (Golden Girl being Japanese-American and Human Top being black) to Marvel's Golden Age, and were retroactively stated to have fought alongside Captain America and ComicBook/{{Bucky|Barnes}} as members of Comicbook/TheInvaders.
** Ed Brubaker's ''Captain America'' run introduced Codename Bravo, one more of Cap's supposed allies from UsefulNotes/WorldWarII. He also introduced Queen Hydra, a female HYDRA agent from the same era.
* The short-lived series ''The Crew'' revolved around [[Comicbook/WarMachine James "War Machine" Rhodes]] trying to take down the drug lords responsible for the death of his younger sister. Not only was the sister never mentioned prior to this, she was pretty much never mentioned again ''after'' the series ended either! The sister was eventually mentioned again years later in the ''Iron Patriot'' limited series...so that it could be established that she had a daughter, Lila Rhodes, who is apparently very close with James despite having never been seen or mentioned before. The series also added a previously-unmentioned son of the above-mentioned Isaiah Bradley - Josiah al hajj Saddiq - who'd apparently been around since the sixties and had become a superhero.
* ComicBook/{{Daredevil}}'s childhood mentor Stick wasn't introduced until ''Daredevil'' #176, which was published a whopping 17 years or so after the title's debut.
* Paulie in ''ComicBook/DeadlyClass''. Having never appeared previously, he runs into Marcus during finals and insists that he's always been around, is friends with everybody, and is known for his lucky {{red shirt}}. [[spoiler:Amusingly, he makes it through finals unscathed, and goes on to have a cozy spot as Viktor's YesMan by the class's sophomore year.]]
* This trope was the favorite approach of Creator/CarlBarks when introducing new characters in the ComicBook/DisneyDucksComicUniverse, and several of his successors take similar approaches. Characters like Uncle Scrooge, Gladstone Gander, Gyro Gearloose and even the Beagle Boys were all introduced in stories that treated them as if they'd always been there, just not on-page (though Scrooge admittedly is introduced as a solitary miser who hardly ever gets in touch). In this case it works, largely because the Duck comics tend to be standalone stories that operate on NegativeContinuity.
** This approach is also used by Italian authors: Brigitta [=McBridge=] is stated in her debut story to have known Scrooge since at least 1898 (back when Scrooge had moved to Whitehorse and became a businessman), with a later story showing their first encounter actually dates to when Scrooge was a prospector and had just struck rich; Jubal Pomp debuts as a recurring annoyance of Scrooge, and a later story actually puts their first meeting at the same time as the one between Scrooge and Brigitta; and Gideon [=McDuck=] was presented as Scrooge's younger ''brother'' (this was many years before ''ComicBook/TheLifeAndTimesOfScroogeMcDuck'' was published. Nowadays Gideon appears from time to time, but his relation to Scrooge is left out).
* An issue from 1989 revealed that Comicbook/DoctorStrange had a little brother named Vic Strange. The excuse for why we'd never heard of him was that Vic had been hit by a car after an argument with Stephen, with his body placed in cryogenic stasis until medical science could advance far enough to save his life. That explains why Vic had never been ''seen'' before, but not why Strange had never ''mentioned'' him prior to this.
* In the ''ComicBook/DoctorWhoTitan'' Twelfth Doctor story, "The Swords of Kali", a character named Tiger Maratha is introduced who was supposedly a companion of the Fourth Doctor, only to be instantly killed off by the story's villains.
* In DC's second ''ComicBook/HawkAndDove'' series, Dawn Granger (the second Dove) was stated to be an only child. Flash forward to 2005: After Dawn was retconned to have actually been alive after her supposed death in ''ComicBook/{{Armageddon 2001}}'' (a long story), she showed up in the pages of Teen Titans with a bratty younger sister named Holly Granger, who was apparently away living in England all this time. What made it stranger is that they tried to rectify this by explaining Dawn's parents were divorced to provide a ''Parent Trap''-like story, when in the ''Hawk and Dove'' series they were shown to be happily married with no issues in their relationship. To make things even MORE confusing: Holly's personality, appearance, speech patterns (does she speak British slang or not?), and her age wound up being cases of DependingOnTheWriter and DependingOnTheArtist. [[spoiler:It's no wonder they eventually killed her off. Shame they never gave her a solid backstory.]] DC did have several {{Crisis Crossover}}s since Dawn's "death" which rebooted history, including one her erstwhile partner, Hawk/Monarch/Extant was a major player in.
* ComicBook/{{Hawkeye}}:
** Trick Shot, the man who taught Clint how to use a bow and arrow, was introduced this way via a {{Retcon}}. He was created to fix the {{Plot Hole}}s that sprung up from having Hawkeye learn archery from the Swordsman, who had never demonstrated any proficiency with a bow.
** As was Barney, Clint's older brother (and later EvilCounterpart). Hawkeye had never mentioned having an older brother in any of his previous spotlight tales, but in ''Comicbook/TheAvengers'' #64, Barney shows up out of nowhere, and the Avengers all already know him as a powerful underworld figure (though they don't learn he's related to Clint until the end of the issue).
* When the ''ComicBook/IronMan'' series was rebooted following ''ComicBook/AvengersDisassembled'' with Warren Ellis at the helm, suddenly Tony had an old mentor in [[Creator/BruceSterling Sal Kennedy]] and an old love interest (one important enough in Tony's life that he actually remembered her when she called) in Maya Hansen. Pepper Potts and Happy Hogan (central characters of Tony's supporting cast since six months after his first appearance) were nowhere to be found. Another reboot post-''ComicBook/AvengersVsXMen'' introduced us to Arno Stark, who was revealed to be Howard and Maria Stark's ''biological'' son, turning Tony into an adopted child. Turns out he was incredibly ill and was hidden away from an alien.
* Creator/MarvelComics character ComicBook/JessicaJones was created in 2001, but has been retconned into various parts of Marvel history, most notably hanging out with [[Franchise/SpiderMan Peter Parker]] the day he was fatefully bitten by an irradiated spider. She later gained powers of her own and was mind-controlled into picking a fight with Comicbook/TheAvengers, leading directly to a severe beating and coma. She recovered with the help of ComicBook/JeanGrey. All of the preceding "happened" before she even debuted in comics. What's more, her origin involved witnessing ComicBook/{{Daredevil}}'s origin; she's been inserted into the fiction ''that far back''. One ''Spider-Man'' comic goes to the point of using a panel from the '60s ''Amazing Spider-Man'' comic and pointing that she was one of the background characters featured in the panel.
* General Glory, a ComicBook/CaptainAmerica parody from ''ComicBook/JusticeLeagueInternational''. Justified since knowledge of his existence was actively suppressed by the government, leading most people to assume he was just a comic book character.
* Skyrocket of ''ComicBook/PowerCompany'' was introduced as a heroine from what would've been about the Silver Age that you simply hadn't heard about. Josiah Power hired her into the Power Company for "credibility"-- Meaning that her being around brought the respect of guys like the Green Lantern.
* ''Franchise/SpiderMan'':
** Early in his career, Spidey fought a trio of criminal mercenaries called the Enforcers rather often, Fancy Dan, Montana, and the original Ox, the last little more than a DumbMuscle thug named Raymond Bloch. Eventually, Ox left the other two to join Mr. Fear's Fellowship of Fear, where he was killed -- or so it seemed -- from a fall during a battle with ComicBook/{{Daredevil}}. It turned out, however, that Raymond had a twin brother named Ronald who was ''also'' a DumbMuscle thug, but whom Raymond had never mentioned. Nonetheless, Ronald joined up with the other two members of the Enforcers to take his brother's place. (And stayed with them when Raymond turned up alive years later, working for ComicBook/TheKingpin.)
** The limited series 'The Thousand' introduced another of Peter Parker's classmates who was there during the spider-bite incident. Unfortunately this was a super-smart sadistic bully, noted for making young Parker eat 'dog sick'. The nutbar figured things out and ''ate'' the now dead power-granting spider. Said bully became a body-hopping crazed killer. It got worse from there.
** ''ComicBook/OriginalSin'' introduced us to Cindy Moon, who would go on to become ComicBook/{{Silk}}. She was introduced as another person who was there at the experiment that gave Peter his powers and was even bitten ''by'' the same spider before it died. She was picked up by Ezekiel Sims in an attempt to protect her from Morlun and never bothered to tell anyone connected to him.
** Carlie Cooper was supposedly good friends with Gwen Stacy and Gwen's dad Captain Stacy supposedly worked with Carlie's dad as well. [[SarcasmMode This completely endeared her fandom and stopped the phrase "Mary Sue" from being associated with her]].
** Subverted with Clayton Cole, a 2014-debuting teenager who was also "introduced" as having been around during Peter's high school/early Spider-Man days. This mechanically gifted but otherwise chronically shy and introverted, home-schooled teen was one of Spidey's first and "biggest"[[note]]from Clayton's perspective, [[ButForMeItWasTuesday not so much Spidey's]][[/note]] fans from his wrestling days, and even [[LongRunnerTechMarchesOn helped]] (in his mind) spread the transitioning Superhero's popularity. Deciding he wants to be a hero, too (in part to be close to his idol, but also for fame soaking-up purposes), he creates his own costumed identity, complete with homemade sound-based powers, dubbing himself "Clash". Alas, his first meeting in-costume with Spidey didn't go so well, ending with Spidey declaring/treating the bumbling newbie as just [[CreateYourOwnVillain another villain]]. The popularity his Clash persona ends up receiving going straight to his head coupled with Spidey spurning him causes Clayton to snap, culminating into the final "confrontation" at school, with Spidey unmasking the newly-dubbed "Creepy Clayton". This Trope is subverted in Clayton's case because, despite the trappings, no one ''actually remembers'' Clayton; for Peter, he was nothing more than an early career blip that largely resolved itself. Clayton also has more of a happier ending later in his life then many similar others, and despite his and Spidey's history, doesn't really become more than a minor supporting character in Peter's life.[[labelnote:Details]]After the unmasking, Clayton ends up in juvie. He's on parole 13 years later, and due to his circumstances, has to hire himself out as a masked scientist goon to get any work. Having largely matured and mellowed out since his short-lived, yet life-defining Clash days, he turns on his employer and helps Spider-Man foil her plans. In turn, Spider-Man, who's also [[CharacterDevelopment matured vastly]] from his teenage years, directs the now-bearded Clayton (whom he does eventually recognize) toward Parker Industries, where an equally-matured Peter welcomes him with open arms. Thus, Clayton is now a loyal, if somewhat minor (compared to a few of his fellow employees), scientist working for Parker Industries, albeit while still on parole (so he cannot be seen in any costume, even if he helps Peter/Spidey out in a crisis situation, a la the Ghost sabotage).[[/labelnote]]
** In Creator/MarkWaid and Creator/JamesRobinson's ''Amazing Spider-Man: Family Business'', it is revealed that Spider-Man ''supposedly'' has a long-lost younger sister named Teresa. ''Supposedly'', because it is unclear whether or not Teresa is really his sister since Mentallo was responsible for putting a perception filter effect on her.
** Creator/ChipZdarsky's ''Peter Parker: The Spectacular Spider-Man'' introduces Hophni Mason, the heroic brother of the Tinkerer. He's been repairing superhero tech for years, and counts characters like Comicbook/AntMan, Comicbook/TheFalcon and even Iron Man among his clientele. Peter is completely surprised to learn of Hophni's existence, and wonders why his fellow heroes never told him about the guy.
** The Janice Lincoln version of the Beetle is an interesting example. She was around as a minor villain for a little while, but wasn't revealed to be the daughter of Tombstone (a fairly prominent Spider-Man villain) until she started appearing in ''Comicbook/TheSuperiorFoesOfSpiderMan''. The fact that we'd never seen her before was subtly lampshaded, as it turns out that her dad purposefully steered her away from the world of costumed supervillainy so that she could make even ''more'' money as an attorney.
* ''Franchise/{{Transformers}}'':
** Originally in Marvel's ''[[ComicBook/TheTransformers Transformers]]'' comic, Sparkplug Witwicky's teenage son was named Buster, and he was clearly supposed to be the same character as Spike Witwicky on the TV series. Four years later, Hasbro released the toy Fortress Maximus, who came with a figure named Spike Witwicky. So, in the comics, Buster was suddenly revealed to have an older brother named Spike who had been away from home all this time.
** The Marvel comic also did a lot of this with introducing new characters whenever their toys came out. The Decepticon Pretenders are particularly obvious, because the six of them are claimed to have been there all along among Scorponok's crew.
** Played straight in ''ComicBook/TheTransformersAllHailMegatron'', because Scourge (who makes his IDW debut here) is part of the neutral dead universe faction of Transformers, despite all of them being established in a past miniseries, Scourge just shows up among the casualties, and the narration hints he was there all along.
* ''ComicBook/TheTransformersCombinerWars'': Due to the new combiner toys getting shilled out, Blackjack and Off Road show up amongst the Stunticons just in time for their inevitable combination. While Off Road is addressed as being the new guy on the team, Blackjack's treated like he's been there all along, which is odd considering in issue 2 Blackjack was a member of the Secret Police assigned to the Stunticons.
* Toni Ho from ''Comicbook/NewAvengers2015'' is the daughter of Ho Yinsen, a prominent character from Comicbook/IronMan's origin. The fact that she'd never been mentioned or seen before (despite Yinsen's son having appeared in the past) was explained as her parents having divorced when she was a kid, meaning she grew up in America while her dad stayed in Asia.
* Ava Ayala, the most recent ComicBook/WhiteTiger and the [[LegacyCharacter younger sister of the original]]. This wasn't an issue in ''WesternAnimation/UltimateSpiderMan'', the cartoon she was created for, but became a bit weird when she became a CanonImmigrant. The original White Tiger now has [[AssPull a teenage sister we've never heard of]], who's significantly younger than his own niece.
* Sam Alexander, the newest Comicbook/{{Nova}}, is another ''USM'' CanonImmigrant who fell into similar problems. He worked fine in the context of the show, but in the comics, the Nova Corps had been wiped out several years earlier during ''Comicbook/TheThanosImperative''. To justify Sam's existence, the writers had to come up with the idea that there had been a second, black-clad group of Nova Centurions (who Sam's dad was a part of) [[AssPull that had been around for years]]. Later ''slightly'' justified during ''Comicbook/OriginalSin'', where it's revealed that the black Novas were essentially a rogue splinter group, and that Sam's dad infiltrated their ranks to keep tabs on their shady activities.
* In general, this is the case for many CanonImmigrant characters. For instance, when Melinda May made the jump from ''Series/AgentsOfSHIELD'' to the comics, she was introduced as a legendary ComicBook/{{SHIELD}} operative that had apparently been around for years, despite never having been seen or mentioned in any prior comics. This specific case is slightly justified though, since S.H.I.E.L.D. is a massive organization that employs tens of thousands of agents across the globe. It makes sense that we've only ever met a small fraction of them in the actual books.
* ComicBook/BlackPanther:
** Princess Shuri, T'Challa's little sister, was introduced as a young woman in a 2005 issue of the series, with everyone acting like she's always been there. The same writer also gave T'Challa an unnamed younger brother who was killed by Klaw, though unlike Shuri, he's almost never remembered or mentioned.
** The Dora Milaje didn't exist until Creator/{{Christopher Priest|Comics}}'s run, but are nonetheless treated as an indispensable part of the mythos at this point. Same goes for Hunter, T'Challa's adopted older brother.
** Ramonda, the Queen Mother of Wakanda, didn't exist until 1989. However, unlike many other examples of this trope, there's a good reason why she wasn't seen or talked about beforehand. She had been kidnapped and imprisoned shortly after T'Chaka's death, causing everyone to assume she'd left the country to be with a new man.
* The Black Order were introduced in ''Comicbook/{{Infinity}}'' as Comicbook/{{Thanos}}' elite generals, with the implication that they'd been around for quite some time. At one point, Supergiant even mentions that Thanos recruited her from an orphanage back when she was a child. The team had never appeared or been mentioned in any of the decades worth of previous stories featuring Thanos, and in fact, Thanos had traditionally been depicted as relying on others as little as possible when he could help it.
* ''Comicbook/XMen'' does this over and over and over again. Siblings like Sunfire's sister Sunpyre and Xavier's twin Cassandra Nova were always there. The "original" new team of all-new-all-different X-Men consisted of Vulcan, Petra, Sway and Darwin, who mostly died (two of them got better). Sage has always been Xavier's personal spy since she was the first mutant he met, but never did anything (nothing mutantly, anyway, she was an established if extreeeemely minor character for decades) during the regular stories. Elias Bogan has always been a long-lived influential figure of the Hellfire Club.
** Cassandra Nova at least justified it - she was deliberately hiding her presence, and since she has PsychicPowers stronger than Charles' it's not inconceivable that she could.
** The situation with Sunpyre was actually {{lampshade|Hanging}}d. Immediately after meeting her, Jean Grey confusedly stated that she'd known Sunfire for years and he'd never mentioned having a little sister.
** Sage was present in the comics for years, and her mutant and spy status is arguably a case of either this trope or {{Retcon}}: in fact, it was teased at off-and-on during several of Claremont's plot threads. The origin story of the ComicBook/NewMutants, for example, has her randomly help the New Mutants against Pierce and the Hellfire Club (her employers). Xavier does ''declare'' not to trust her, but we're never told if it's just to cover up her status as TheMole, or if he's afraid of a BecomingTheMask scenario. Anyway, that was '''20 years before''' Sage's [[TheReveal reveal]] as Xavier's spy.
* The original Baron Zemo was introduced this way. He was stated to have been one of Captain America's deadliest foes back during UsefulNotes/WorldWarII (he was even responsible for the death of Comicbook/BuckyBarnes), but his first published appearance was a [[UsefulNotes/TheSilverAgeOfComicBooks Silver Age]] issue of ''ComicBook/TheAvengers''. Zemo is an interesting case. He was introduced in said ''Avengers'' issue and just a few months later appeared in an issue of ''[[ComicBook/NickFury Sgt. Fury]]'' (a flashback series set during UsefulNotes/{{W|orldWarII}}W2) to cement his place as a 40s era villain.
* The Blue Marvel was introduced as a black [[UsefulNotes/TheSilverAgeOfComicBooks Silver Age]] superhero [[{{Deconstruction}} who was forced to retire due to the institutional racism of the 60s]]. He ended up coming out of his exile during the 21st century to help ComicBook/TheAvengers battle his old nemesis.
* Parodied (?) with SelfDemonstrating/{{Deadpool}} as there have been a number of comics and mini-series that place him in various eras of the Marvel Universe that predate his creation-- teaming up with Iron Fist and Luke Cage during their "Heroes for Hire" era, taking over for Iron Man during the "Demon in a Bottle" era, even showing up in the original ComicBook/SecretWars and bonding with the ComicBook/{{Venom}} symbiote. However, it's quite hard to tell which of these stories (if any) have actually happened and which ones are simply {{What If}}s created in the spirit of fun (particularly when you remember that it's already been established that 1) Deadpool's mental instability has been known to mess with his memory and 2) he's aware that he's a comic book character, thus subject to MultipleChoicePast).
* Similarly, Sally Floyd was created for the mini series ''Generation M'', after the events of ''House of M'', with the reader being informed that she had multiple interviews with famous mutants and dated Angel. She was apparently a friend and confidante of X-Men such as Jubilee, Beak and Dani Moonstar, but was simply never seen or mentioned until now.
* Union Jack was another Marvel character from the Silver Age that was retconned into the Golden Age. In fact, an actual Golden Age Marvel hero was retconned into being the first Union Jack but in a disguise.
* DC Comics had several heroes that were created in the 70s and 80s, but were established as having been active during the 40s. Among them were Amazing-Man (chronologically, one of the earliest black superheroes) and [[Comicbook/{{Steel}} Commander Steel]], both of whom were established as having fought alongside the members of the [[Comicbook/JusticeSocietyOfAmerica JSA]].
* This happens to Barbara Gordon so much that's it's a RunningGag.
** Katarina Armstrong, the second Spy Smasher introduced late into the first volume of ''ComicBook/BirdsOfPrey'', was a college roommate and rival of Barbara's. She had never been referred to before that.
** Munira Khairuddin, AKA Obscura, debuted more than halfway through Barbara's [[ComicBook/Batgirl2011 New 52 series]] and was ''also'' established as a former college classmate and rival, despite never having been mentioned prior.
** Frankie Charles, who made her first appearance in the Burnside era of ''ComicBook/Batgirl2011'', had been an acquaintance Babs knew from her time in physiotherapy.
** In the first issue of ''ComicBook/BatgirlRebirth'', Barbara happens to run into a man named Kai, a childhood friend of hers who, once again, had not been seen or referred to prior.
* Speaking of ''Rebirth'', there's an odd variant of this trope with Comicbook/{{Batwoman}}. The character has been around since 2006, but didn't have any real ties to Batman, even after it was revealed in a later story that they were cousins. Suddenly, ''Comicbook/DetectiveComicsRebirth'' establishes that Kate and Bruce were quite close when they were children, and that Kate even comforted Bruce at his parents' funeral.
* ''[[Comicbook/DCRebirth Rebirth]]'' also establishes that the ComicBook/{{New 52}} Wally West is ''not'' a {{Race Lift}}ed version of the original Wally West. The original Wally immediately recognizes Wally II and states that the boy is his cousin, implying that he (and by extension, his father, Daniel West) existed in the previous continuity as well. At no point in any of the decades worth of prior ''Flash'' stories did Wally ever mention having a cousin who was also named Wally.

[[folder:Fan Works]]
* Ash Ketchum's younger sister Chibi and twin brother Dash in the ''Anime/{{Pokemon}}'' fic ''Fanfic/GuardiansOfPokemon''. Lampshaded as far back as the first chapter.
* In ''Fanfic/MyImmortal'', most of the ''Literature/HarryPotter'' characters appear to have met Ebony sometime prior to the story. [[WordOfGod Word Of]] [[OhMyGods Satan]] even tries to explain why Draco is OutOfCharacter by saying that he already knew Ebony. Oddly, averted with Harry himself, creating one of many continuity problems (apparently, Harry was in Ebony's "goff" band before they first met).
* ''Fanfic/MyLittleUnicorn'':
** [[spoiler: Turns out, the second main antagonist of ''My Brave Pony: Star Fleet Magic II'' is Cadance's brother Fratello, who we never heard of before. Not to mention that Equestria seemingly has been invaded by robots around 15 years ago, of which no one has a memory of.]]
** Another example would be Krysta's adopted son Twink, who suddenly appears with no foreshadowing in ''My Brave Pony: Star Fleet Magic II'', Episode 1. When asked about why he suddenly appears, Mykan answered "New characters get thrown in all the time (everyone knows that)".
* Lampshaded in the [[https://www.fanfiction.net/s/7710088/1/Prayer-Warriors-Battle-With-The-Witches-COMMENTARY commentary]] on ''Fanfic/ThePrayerWarriors [[Literature/HarryPotter Battle With the Witches]]'', when the protagonist, Michael, is referred to as a "dear friend" and follower of Jerry; the commentary says "If he's so dear, why is he only appearing now?" Then again, it's a less extreme example than most cases, since he was earlier shown carrying out Jerry's orders to execute Mary for adultery in ''[[Literature/PercyJacksonAndTheOlympians The Evil Gods Part 1]]''.
* {{Lampshade|Hanging}}d in ''[[WebVideo/YuGiOhTheAbridgedSeries Yu-Gi-Oh: The Other Abridged Movie]]'', an adaptation of Toei's ''Yu-Gi-Oh!'' movie:
-->'''Yugi:''' Those bullies are being mean to [[MartyStu Gary Stu]]!\\
'''Joey:''' Who the hell is Gary Stu?\\
'''Yugi:''' I don't know, but apparently, he's my best friend.
** In the original, Yugi never claimed to know Shougo (the character Gary Stu is based on) very well. They were just neighbors.
* Many crossovers written so that the two stories are set in the same universe frequently contain this as a method of bringing the cast of the two series together.
* More than one MarySue is introduced this way in fanfiction.
* ''WesternAnimation/{{Daria}}'' fandom has [[https://dariawiki.org/wiki/Veronica_Morgendorffer Veronica]], the third Morgendorffer sister. Her original story had this trope PlayedForDrama--Daria couldn't remember her, but everyone acted like she'd always been there, leading to a mystery of whether it was an elaborate trick or some kind of LaserGuidedAmnesia. Other fans then started including her in stories, often with [[PlayedForLaughs the joke]] that Daria literally can't remember her from day to day. Otherwise, she's just an added element for AU fics.
* Played with in "Fanfic/TheOnlyWayToGo". Captain Kanril Eleya is aware of the real story of the Battle of Goralis and was based out of Deep Space 9 at the time of the battle, but she hadn't been added to ''Fanfic/TheWarOfTheMasters'' yet so she didn't appear in ''Fanfic/FacesInTheFlames''. Rather than {{retcon}} ''Faces'', the authors {{justified|Trope}} her absence with her having been dealing with a problem with the Tzenkethi when everything blew up.
* Lampshaded and PlayedForLaughs in ''FanFic/SonicXDarkChaos'' when Eric the Hedgehog shows up out of nowhere and Chris asks who he is.
-->'''Chris''': You guys never told me there was another hedgehog like Sonic on your planet!
-->'''Amy''': Yeah, and [[TheFriendNobodyLikes there's a reason for that]].
-->'''Knuckles''': Believe us Chris, you're lucky he didn't get teleported to your world with us last time.
* The KimagureOrangeRoad fanfic ''Ordinary World'' nonchalantly introduces us to Kyosuke's cousin, and Akane and Kazyua's older brother, Musoka. However, things are not as they seem. [[spoiler: Musoka really IS Akane and Kazuya's older brother. He's also an extremely powerful telepath that can implant and remove memories. The reason we've never seen him before is because he removed his existence from the character's memories, and what we've seen is what they remember (since Kyosuke is, as always, narrating the story from the future). It gets ever stranger, since Musoka creates the character of the Master of ABCB from whole-cloth and pretends to be him; meaning he's actually been there all along!]]
* In ''Fanfic/DaringDoAndTheJourneyToTheCenterOfTheEarth'', Gummy appears halfway through with absolutely no explanation and is treated as if he was with the main characters all along. In this case, Gummy is an established character in the show, but had not previously been mentioned in the fanfic at all.

[[folder:Films -- Animation]]
* In ''WesternAnimation/DespicableMe2'' Gru does this for the major villain. [[spoiler:Justified as he was a villain twenty years ago, and had faked his own death.]]
* Franchise/{{Disney|AnimatedCanon}} DirectToVideo sequels seem to do this quite a bit:
** ''Disney/LadyAndTheTramp 2'' does this with the junkyard dogs. Tramp was apparently best friends with Buster and possibly part of their gang, but Tramp is shown to be a loner during the original film.
** ''Disney/TheLionKingIISimbasPride'' introduces an ''entire pride'' of evil lionesses that supposedly were present during Scar's reign and supported him. They look different enough from Simba's lionesses that it can't be said they were always there, and besides, there are a couple males among them. Meanwhile, Simba's mother does the opposite and [[ChuckCunninghamSyndrome disappears off the face of the earth]] without even a passing "she left/died" explanation. Go figure.
** In ''Disney/TheLittleMermaidIIReturnToTheSea'', "Ursula's crazy sister" Morgana is introduced as the BigBad. Of course, she was never shown in [[Disney/TheLittleMermaid the first movie]]; there wasn't even a clue to Ursula having a sister, and the old characters already know her. In fact, some fans believe that the only reason Morgana was created, is that Pat Carroll wanted to return for the sequel, despite Ursula being long dead.
* Lampshaded in ''WesternAnimation/PenguinsOfMadagascar'' when the BigBad Dave makes his big entrance; none of the penguins has a clue as to who he is.
* ''WesternAnimation/TotallySpiesTheMovie'' has Jerry's assistant Tad and Alex's pet pig Oinky. Since the movie is a prequel to [[WesternAnimation/TotallySpies the series]], their absence in the series is explained with Tad getting arrested and Oinky going to live at an animal shelter. Though Tad is replaced by an agent named Vincent, whose absence in the series is not explained, Oinky would later return in [[PostScriptSeason season 6]].
* ''WesternAnimation/ToyStory2''. When Woody meets Wheezy the Penguin from ''Toy Story 2'', his reaction is why he's up on the shelf with him instead of being away to get his squeaker fixed. {{Justified|Trope}} in that either Andy or Molly may have gotten Wheezy either for Christmas or their birthdays between the first two movies, maybe even for the Christmas they were celebrating at the end of the first one. After all, Buster and Mrs. Potato Head were also Christmas gifts at the end of the first one… Oddly enough, Woody and Buzz do mention being friends with Wheezy prior to ''Toy Story 2'' -- in an "out of character" interview with the characters about the "filming" of the first movie.
* ''WesternAnimation/TheTransformersTheMovie'' notoriously killed the beloved cast of the cartoon (traumatizing many children in the progress) largely to sell new toys of never-before seen new characters.
* In ''WesternAnimation/{{Cars}}'', real-life NASCAR driver Richard Petty played the veteran racer Strip Weathers, who retired at the end of the film. ''WesternAnimation/{{Cars 3}}'' introduces his nephew Cal, played by Petty's real son and fellow racer Kyle, as Lightning [=McQueen=]'s friendly rival. What makes it feel odd is that he too is now on the verge of retirement, implying that he and [=McQueen=] have a long-standing relationship, and also has a very minor role.

[[folder:Films -- Live-Action]]
* ''Film/AvengersAgeOfUltron'' introduces Dr. Helen Cho, a renowned Korean scientist who serves as a medical and scientific ally to the team. She's close friends with both Bruce and Tony, but like Alexander Pierce below, she is neither seen nor mentioned in any of the previous movies.
* In ''Film/BatmanReturns'' (1992), Max Shreck has apparently been one of Gotham City's most famous residents for quite some time ("Here's a man who needs no introduction, he's given so much"), having been around long enough to have established the town's most successful department store, become more wealthy than anyone except Bruce Wayne himself, gotten a mayoral candidate elected, ''and'' gained enough influence to propose the construction of a new electrical power plant. So it's strange in retrospect that he apparently didn't exist at the time of [[Film/{{Batman}} the 1989 film]], particularly since Gotham's 200th anniversary festival budget was seriously short on funds and he would probably have been the most philanthropic contributor. Shreck's Department Store is arguably an even more blatant New Guy: if we are to assume that the cathedral entrance on the opposite side of the city square, which we see behind the Penguin as he escapes on his helicopter umbrella, is to the same cathedral in which the Joker hid out at the climax of the previous film (and, at least according to {{Fanon}}, it is), the store is so big and so gaudy that it wouldn't previously have been missed. Of course, it's possible that, in-universe, ''Batman Returns'' is taking place many years after the original film; however, as all the returning cast members look to be about the same age as before (which they are, of course), that isn't likely.[[note]] This is because Max Shreck's role in the film was originally filled by Harvey Dent, returning from the 1989 film, who was supposed to be given the disfigurement that turns him into Two-Face by Catwoman at the end of the film. Of course, all this was changed.[[/note]]
* Alexander Pierce is introduced in ''Film/CaptainAmericaTheWinterSoldier'' as a high-ranking member of ComicBook/{{SHIELD}} and ComicBook/NickFury's close personal friend. Prior to his debut, he'd never been mentioned in ''Film/{{The Avengers|2012}}'' or any of the other [[Franchise/MarvelCinematicUniverse MCU]] films. WordOfGod from the creators was that this is one of the major reasons Jasper Sitwell [[spoiler:was chosen to be a HYDRA mole. Most of the double agents in the movie were new characters that hadn't appeared in any other films, and the filmmakers felt it'd be a cop-out to introduce such a massive conspiracy and not have it involve any established characters]].
** Pierce's situation seems especially odd that in that it appears he's Fury's ''superior'' (or at least the politically-appointed head of SHIELD while Fury is the operational leader), whereas ''Film/{{The Avengers|2012}}'' implies that Fury reported directly to the Council. ''Series/AgentsOfSHIELD'' further confuses the issue because a flashback established Pierce had been in a high-ranking position years earlier.
* A few characters who were in ''Literature/{{Divergent}}'' but got left out of [[Film/{{Divergent}} the film adaptation]] - such as Uriah and Marlene, appear in ''The Divergent Series: Insurgent'' along with the rest of the Dauntless. As the first film mainly focused on Tris and her three friends, we can assume they were there but we just didn't see them.
* ''Film/TheGodfather'':
** Frank Pentangelli in Part II is supposed to be a high level member of the Corleone family since the beginning even though he doesn't appear at all in the first movie. The reason he was created was because Clemenza who was in the Part I and was supposed to be in Part II couldn't be used because the actor playing him did not return.
** The third film has the previously unmentioned Don Altobello who is not simply an important mafiosa but a ''very'' long term, trusted ally of the Corleones - he is Connie's godfather.
* ''Film/HaloNightfall'' introduced a never-before-seen Covenant species, the Yonhet, despite taking place ''after'' the original ''Franchise/{{Halo}}'' trilogy. In this case, Creator/ThreeFourThreeIndustries somewhat covered their tracks by introducing them as part of an entire "Covenant Fringe", a collection of Covenant-allied species too weak to have seen military action against the humans during the Human-Covenant war, and too small in population to be of much notice to the core Covenant races.
* ''Film/HighlanderIITheQuickening'' just sort of... drops a new BigBad, General Katana, into [=MacLeod=]'s backstory and expects the viewer to roll with it. Hell, it drops an [[VoodooShark entire new backstory into MacLeod's backstory]] (that [=MacLeod=] is actually a space alien who has been politically exiled by Katana from planet Zeist) and acts like it all fits together despite the new backstory being almost completely incompatible with any of the details from the original film.
* ''Film/HighlanderEndgame'' had two major examples: Jacob Kell, Connor's former childhood friend who betrayed him and murdered his mother, and Kate/Faith, Duncan's Immortal ex-wife. Made even worse by the fact that ''Series/HighlanderTheSeries'' had previously stated in no uncertain terms that Duncan ''never'' had a wife.
* ''Film/JasonGoesToHellTheFinalFriday'' introduces Jason's half-sister Diana. No mention had been made about living Voorhees family members in preceding ''Franchise/FridayThe13th'' films.
* Lampshaded and parodied in ''Film/LastActionHero''.
** The ShowWithinAShow film franchise, Jack Slater, shows Arnold's character rushing to save his daughter from a previous marriage. The main character, a "real" young boy who has been sucked into the movie, points out that Slater has never mentioned his daughter before and is annoyed that the filmmakers were introducing a new character into the franchise in this manner.
** Lampshaded again, in a different way, when we meet Creator/FMurrayAbraham, who in the Slater verse is introduced as one of Slater's old cop buddies. Danny correctly pegs him as a traitorous bad guy because he's played by F. Murray Abraham, though presumably also because he's never heard of his character either.
* O in ''Film/MenInBlack3'' never appeared in the first two films but apparently had been working at MIB for at least as long as K had.
* Done deliberately and repeatedly in ''Film/MontyPythonAndTheHolyGrail'', with King Arthur's entourage growing and shrinking exactly as needed for the current scene being played. Special mentions go to Patsy, to Brother Maynard and his disciples, and of course to Arthur's entire army that appears in the very last scene and is implied to have been there off-screen throughout the entire movie.
* ''Film/TheRoom'' has a really lazy example. With about 20 minutes left in the movie, a new character, Steven (whose name is mentioned only in the credits) suddenly appears and becomes deeply involved in the plot. Presumably, we're not supposed to notice that he suddenly appeared from nowhere without an introduction. WordOfGod is that Steven is supposed to be a replacement for the psychologist character Peter (whose actor left the production), but the audience is given no hint of this; indeed, Steven looks nothing like Peter, he doesn't even dress like him.
* ''Film/TheSmurfs''. Gutsy, because Hefty wasn't Scottish enough.
* ''Film/TheSmurfs2'' introduces Hackus and Vexy, two artificial Smurfs created by Gargamel. The fact that they weren't in the previous film(s) is justifiable, as they hadn't been created yet. What ''isn't'' justifiable is that ''the movie never actually introduces them'' — we just meet them being up to some hijinx as though who they were had already been established.
* ''Franchise/StarTrek'':
** ''Film/StarTrekIITheWrathOfKhan'':
*** Khan meets Chekov and says he knows him because "I never forget a face." Which means that Chekov was on ship during "Space Seed," a first-season episode, despite the character not appearing on screen until the second season. Numerous explanations have been thrown about (he was on the ship, just not as bridge crew; Chekov was the officer in charge of delivering the supplies and food to Ceti Alpha V; an obvious joke about Chekov occupying a latrine Khan wanted to use), but ultimately it comes down to this trope.
*** Another example from ''Wrath of Khan'' is Doctor Carol Marcus, Kirk's old flame. They even had a son together. [=McCoy=]'s aware of her too (presumably from back in the day). And yet we're only hearing about her now, after all these years. Justified, however, in that Kirk slept with a ''ton'' of women. (And assuming David is the same age as his actor, Merritt Butrick, he would have been born, and Kirk and Carol's relationship would have been, several years before the original series, and Kirk explicitly states he "stayed away," as Carol wanted, after David was born.)
*** Some have speculated that Carol Marcus was the "blonde lab technician" that Gary Mitchell set Kirk up with, mentioned in the second pilot ''"Where No Man Has Gone Before"''.
** Valeris in ''Film/StarTrekVITheUndiscoveredCountry'', as a replacement for Saavik. The first drafts of the script ''did'' have Saavik in that part, but the writers ultimately decided that having Saavik [[spoiler:betray the crew of the ''Enterprise'' and frame them for the assassination of Gorkon]] just didn't make sense for her character.
*** This is something that's been disputed by Nicholas Meyer. While he wanted it to be Saavik, but Roddenberry leaned on him a bit because he didn't believe it'd fit the character. Meyer may still disagree, seeing as how he came up with Saavik to begin with.
** ''Film/StarTrekGenerations'': Kirk's ultimate fantasy world in the Nexus involves the one true love of his life... who we've naturally never heard of before despite Yeoman Rand, Carol Marcus, or even Edith Keeler now being quite viable options for that role. In fairness, the original series made it plain that Kirk had plenty of old girlfriends, and he made quite a few new ones along the way (this is ''Kirk'', after all). The real surprise is that David Marcus was his ONLY child.
*** Explained in the novelization of the movie; what Kirk actually did was experience similar fantasies with all of the women he'd truly been in love with.
** Captain Picard remembers the Borg Queen when she's first introduced in ''Film/StarTrekFirstContact''. Could be justified by the fact he ''was'' a Borg for a while, but that doesn't explain why he doesn't mention this vital piece of information about a dangerous enemy onscreen, and Data seemingly knows nothing about her despite the fact that he presumably would have read any report Picard made after the incident. They attempt to {{handwave}} this by implying that Picard had forgotten about her until they're reintroduced in the film.
* ''Franchise/StarWars:'' ''Film/RogueOne'' is a prequel to ''Film/ANewHope'' about how the plans for the original Death Star were stolen, and introduces Director Orson Krennic of the Imperial Security Bureau as a primary player in the Death Star's development, [[TeethClenchedTeamwork butting heads with both Grand Moff Tarkin and Darth Vader himself]] during the film. [[spoiler: Somewhat justified since he's killed near the end of the movie and has his position in charge of the Death Star taken by Tarkin, explaining why he didn't appear in ''A New Hope''.]]
* ''Film/Terminator3RiseOfTheMachines'' introduced Kate Brewster, a childhood friend of John Connor, whom he last saw prior to the events of ''Film/Terminator2JudgmentDay'', and who becomes one of the leaders of the Resistance following Judgment Day, as well as Connor's wife. The previous two films in the series never mentioned her.
* ''Film/ThorRagnarok'':
** Due to having become a fugitive after the events of the [[Film/ThorTheDarkWorld previous movie]], Heimdall has been replaced as the guardian of the Bifrost by a new character named Skurge. Despite never having appeared in the previous films, Skurge has apparently been around for a while, and claims to have fought alongside Thor in the past. It's {{handwave}}d by having Thor not recall the battle in question, which makes sense given [[ButForMeItWasTuesday all the crazy adventures he's gone on by this point]].
** Justified case with Hela. [[spoiler: She's Odin's eldest child and Thor and Loki's older sister, but all evidence of her existence was covered up by Odin after she went rogue and had to be imprisoned.]] Throughout the movie, she's shown to be bitter about the fact that nobody remembers her.
* ''Film/WarForThePlanetOfTheApes'' features a love interest for Blue Eyes named Lake. She's treated as though she has always been a member of the colony, even though she wasn't seen in the [[Film/DawnOfThePlanetOfTheApes previous movie]]. Red is also said to have been one of Koba's coconspirators in the previous film, but like Lake, he didn't actually appear in it.
* ''Film/XMenFilmSeries'':
** ''Film/XMenDaysOfFuturePast'':
*** When debating how to break out Magneto, Wolverine casually announces he "knows a guy." Said guy turns out to be ComicBook/{{Quicksilver}}, who has not appeared or been mentioned in any of the six previous ''X-Men'' movies.[[note]]This line of dialogue is actually TheArtifact. In the original script, the teen who helped Wolverine was a young version of Cain Marko, AKA The Juggernaut, who he did actually encounter in ''Film/XMenTheLastStand''.[[/note]] {{Justified|Trope}} though if he met him in the decades since the last movie.
*** The future portion of the film fully incorporates the idea from ''First Class'' which established that Charles and Mystique grew up together. It can seem a bit jarring to see Creator/PatrickStewart's Xavier sadly recounting how he once loved Mystique and considered her his sister, when there is absolutely no indication at any point in the original trilogy that the two were ever close or even ''knew'' one another.
** Even earlier than that, ''Film/XMenTheLastStand'' introduced Dr. Hank "Beast" [=McCoy=], a mutant politician who ''everyone'' at the Xavier Institute (other than the latecomer Logan) knows intimately, even though he was never shown or mentioned in the first two movies. ''Film/XMenFirstClass'' and ''Film/XMenDaysOfFuturePast'' rectified the issue somewhat, clarifying that Hank was a student from the Institute's early days who stayed behind when Xavier shut the school down during the Vietnam War.
** ''Film/XMenApocalypse'' is set in the 1980s and has a teenage Nightcrawler join the X-Men even though ''Film/X2XMenUnited'' which was set TwentyMinutesIntoTheFuture had them meet him for the first time as an adult. Though WordOfGod has said the time travel in ''Film/XMenDaysOfFuturePast'' has made the [[Film/XMenTheLastStand third]] and [[Film/XMenOriginsWolverine fourth]] movies [[CanonDiscontinuity non-canon]], which could mean the same for ''X2''.
* ''Film/GoldenEye'' sets up Alec Trevelyan as "006" and one of Bond's oldest friends, in spite of never being mentioned by name, and once by number, in the entire series. Then again, ''Film/GoldenEye'' was supposed to be a soft reboot of the franchise (which was never big on continuity in the first place), so it might be justified.

* ''Literature/{{Brotherband}}'' introduces two important concepts to Skandian society: the Andomal and the Maktig. Neither is mentioned in ''Literature/RangersApprentice'', despite Skandians being prominently featured.
* [[spoiler:Halt]]'s twin brother, introduced in book 8 of ''Literature/RangersApprentice''. {{Justified|Trope}} in that the brother lived in another country and [[spoiler:Halt]] actively avoided telling people about his childhood, as shown in book 11.
* Grave Peril, the third book of ''Literature/TheDresdenFiles'', introduces Michael Carpenter, Knight of the Cross and Harry's longtime friend from at least two years before the books started. He has never been mentioned in any of the short stories, books, or flashbacks set before Grave Peril.
* In ''[[Literature/HarryPotterAndTheHalfBloodPrince Half Blood Prince]]'', Cormac [=McLaggen=] is introduced and tries out for Keeper against Ron. [=McLaggen=] provides an explanation for his absence from the Quidditch trials in the previous book: He was sick in the hospital wing at the time after eating doxy eggs on a bet, also providing his EstablishingCharacterMoment.
** There are some [[Film/HarryPotter movie]]-only examples of this. For example, Lavender Brown isn't in the first five films ([[GhostExtras well,]] [[TheOtherDarrin sort]] [[RaceLift of]]), but she suddenly materializes in the sixth film as a major supporting character.
*** Though one notable exception is Bill Weasley, who doesn't appear until the seventh film, where he and Harry act like they've never met before.
*** The seventh movie has a kind of halfway version. When Dobby shows up, he and Ron act like they've met before. In fact, although Dobby had previously appeared in the second film, he and Ron had never met before -- in the movies, that is. [[AdaptationExplanationExtrication They had met before in the books.]]
* ''[[Literature/InheritanceCycle Brisingr]]'' introduces Nasuada and Ajihad's culture. Not only had they never been previously mentioned (and none of Nasuada's point-of-view segments from the previous book so much as alluded to her culture), but the book tries to act as though they are well known throughout Algaesia and have been part of the Varden. [[RetCon Despite this contradicting what the first book said about nobody knowing where Ajihad came from]].
* Played with in the ''Literature/{{Discworld}}'' book ''Discworld/InterestingTimes'', which reintroduced Twoflower and introduced Twoflower's daughters, Pretty Butterfly and Lotus Blossom. Rincewind insists that Twoflower hasn't mentioned having children and that the whole thing just came out of left field, but Twoflower keeps trying to play the whole thing off, insisting that he "must have mentioned it."
* The Franchise/StarWarsExpandedUniverse plays with this in ''Literature/LegacyOfTheForce'' with Brisha Syo. We know she's Lumiya. We really do. Despite this, Mara assumes she's Luke and Lumiya's daughter. Since Mara and Luke have each other's memories from their Force bond, Lumiya barely kissed Luke, and that TIE crash would most likely have led to a miscarriage, why Mara would even think that only raises even more questions.
** We don't know exactly what happened between Lumiya and Luke in the books' continuity. WordOfGod is that even if they use a character from the comics, they are free to accept or reject anything that took place in said comics.
** By contrast, it's played straight and lampshaded in ''Invincible''. Tenel Ka has cousins? Okay, so Ta'a Chume secretly had more than one son, we'll give her the benefit of the doubt and accept that she managed to hide her pregnancy. And...Tenel Ka has cousins? But the fact that nobody knows about them is what makes them so useful. And, wait, [[RuleOfThree Tenel Ka has cousins?]]
*** It's likely that Kevin J. Anderson left a number of Luke's original twelve students nameless and description-less in Literature/JediAcademyTrilogy for this very reason. At the time of the Legends continuity reboot in 2014, at least one was never positively identified.
* ''Franchise/TheLionKing'' comics and books are bad at this. Many characters, such as Tama, Tojo, and Malka, appear but are never referenced in other material ever again. Very often they're not given any reason for popping up and are just always presumed to be there. A particularly noticeable example is Mtoto, who is Simba's cousin according to a magazine. Sarabi had sisters once, but they were scrapped very early in development. In the final product Nala and Simba are the only two cubs in the Pride. Other examples include the cubs introduced in ''[[Literature/TheLionKingSixNewAdventures Nala's Dare]]'', which apparently were Nala's friends during Scar's reign but are never even implied to exist in the film. In ''The Lion King'' Nala was the only cub in the pride after Simba left.
* In the ''Literature/PercyJacksonAndTheOlympians'' series:
** The Roman Aspects were not mentioned at all in the original Quintet... however ''The Lost Hero'' justifies this in that the Greek and Roman Aspects do ''not'' get along at all, hence the need for them to remain hidden from each other. In fact, a clever reader can point out that the only ones explaining the roman aspects are, of course, Romans, and that the Romans felt this way about the Greeks. (Since Lupa's not one to tell!)
** Related, Jason Grace. Thalia didn't mention having a little brother for several reasons, among them being that the events surrounding his disappearance were ''quite'' traumatic for her and that she thought him dead until this series began.
* The ''Literature/NancyDrew'' series (all versions) frequently introduced characters (usually just for the duration of the current book) as relatives/old friends of Bess, George, Nancy's father, or Nancy herself, essentially explaining their absence by having them live far away.
* The opening chapter of ''Literature/{{Redshirts}}'' by Creator/JohnScalzi plays with this from the New Guy's perspective. This week's RedShirt thinks about the time his father saved the captain's life, and then realises that up until the captain mentioning it just now, there has been no reference to this happening the whole time he was on the ship.
* Peter David's ''Literature/StarTrekNewFrontier'' series had Commander Kat Mueller appear suddenly several novels in. She's introduced as the Executive Officer of the ''Excalibur'' and a former lover of Calhoun's, with her earlier on-scene absence described as being due to her taking the night shift.
** One could say this was justified, as she was ''actually'' introduced as the Executive Officer of the ''Grissom'' in Calhoun's Captain's Table story, along with Romeo Takahashi, Mick Gold, and Doc Villers, the former two of which worked night shift on the ''Excalibur'' before it blew up, and all four work under Shelby (and eventually under Mueller) on the ''Trident'' after.
* In the ''Literature/{{Twilight}}'' series, we hear briefly about the Volturi, mainly that they and Carlisle are on friendly terms, but that he left because he did not agree with their diet of humans. Edward speaks pretty well of them, when he tells Bella about them. In the next book and all books after, it's revealed that the Volturi are a highly corrupt organization, and the Cullens are all highly suspicious of them. This also leads to a case of Remember Those New Rules, since it's not until then that it's mentioned that there are any sort of laws or governing of vampires.
** In ''New Moon'', we find out that the teenagers of La Push had been turning into werewolves ever since the Cullens first settled down in Forks. This is not present in ''Twilight'' (when nothing is done to stop James, Victoria, and Laurent from killing people in Forks) or ''Midnight Sun'' (when nothing is done to stop Peter and Charlotte from killing people in Forks).
*** The James, Victoria, and Laurent example is only in the film version. In the book, they never kill any of the residents of Forks.
* In the ''Literature/WarriorCats'' book ''Moonrise'', six cats were sent to deal with the mountain lion, Sharptooth. The Clan cats meet three of them: Talon, Bird, and Rock, who explain that the other three had been killed by Sharptooth. In the next book, the Clans return to the Tribe, and there's a fourth cat, Jag, listed as being one of the ones originally sent to fight Sharptooth, with no explanation as to why we didn't see him in the last book (though the characters do recognize him and say they'd met him before).
* ''Literature/JamesBond'' novel ''Literature/HighTimeToKill'' introduces one Roland Marquis, a distinguished RAF member and Bond's rival since his studies in Eton. This is actually the first time that anyone from Bond's days of studying had been introduced.
* ''Literature/TheWheelOfTime'': Cadsuane is never mentioned until she appears in the sixth book, even though she is FamedInStory.
** To be fair, the Aes Sedai are known for being extremely secretive even among their own members, and Cadsuane has a history of embarrassing many sisters who would as soon not talk about her unless needed.
* One of the prequels to ''Literature/TheBelgariad'' introduces Belmakor and Belsamber, two previously-unmentioned disciples of Aldur who both committed suicide shortly after the War of the Gods. Their deaths help explain how Mallorea ended up being such a huge blindspot for Aldur's disciples, as Belmakor and Belsambar would have been sent to gather reconnaissance in that region if they'd lived.
** The disciples were mentioned in the series proper as having died in the distant past, though the details were not given until the prequels were published. Each map of the area where the disciples lived shows broken-down towers labeled with their names alongside the other disciples' towers.

[[folder:Live-Action TV]]
* ''Series/AgentsOfSHIELD'' introduces us to Agent Eric Koenig (played by Patton Oswalt) who shortly after his introduction is [[spoiler:murdered by Ward]]. But! He has a twin brother, Billy, also a S.H.I.E.L.D. agent, who is introduced later on, and explicitly described as his ''twin''. In the second season, it turns out there's a ''third'' Koenig brother, Sam, who is also identical to Billy and Eric, and also a S.H.I.E.L.D. agent. Apparently they're actually triplets. Despite Billy referring to himself as Eric's ''twin''.
** This is justified by the nature of the brothers, who like to joke about it and use their similar appearance to confuse other people. On several occasions they imply, that they are either clones or Life Model Decoys (or another form of Robot). In season four, episode 12 it is revealed, that they are quadruplets, who also have a sister (who was foreshadowed in season 2, episode 20). Since she seems totally normal and provides childhood memories, it seems to be clear, they are normal brothers and there will be no fifth.
* Inverted in an episode of ''Series/TheAndyGriffithShow''. Someone comes into town and knows absolutely everyone and everything in the town... but no one else knows who he is. This terrifies the whole town (save Andy) until they start trying to run him out of Mayberry. [[spoiler:Turns out he's actually a drifter who met a Mayberry resident while in the army, read about the whole town through his newspapers, and tried to integrate himself into the town far too quickly.]]
* On ''Series/{{Angel}}'', the guardian of the Deeper Well turns out to be Drogyn, an immortal, [[CanNotTellALie truthspeaking]] warrior who has never been mentioned before, but Angel has already met him. This wouldn't be so odd, since Angel is 250+ years old, except that since Drogyn trusts him and considers him a friend, Drogyn must have met Angel when he had a soul, a period where Angel wasn't doing much besides moping. You'd think that whatever Angel did to earn the friendship of someone like Drogyn would be significant enough for the show to mention earlier. None of the other characters has ever heard of him except [[TheSmartGuy Wesley]].
** Angel's backstory gets this a lot; whether he spent 80 years just moping around or had a bunch of cool adventures is rather DependingOnTheWriter. For example, he also went to Vegas and met Elvis during this period.
** Another example includes Spike and Drusilla knowing Darla; all had been introduced as having traveled with pre-ensouling Angel, but prior to Season 5 of ''Series/{{Buffy|The Vampire Slayer}}''/Season 2 of ''Angel'', they hadn't been demonstrated to know each other. It was previously assumed that Angel traveled with them at different times. While it would be understandable that Darla might not have mentioned them because she traveled alone with Angel for many years, you think at least Spike would have brought up "Whatever happened to Darla?" when he was introduced in ''Buffy'' Season 2.
* ''Series/BeverlyHills90210'' and its spin-off series: Valerie Malone was supposed to be the daughter of the Walshes' best friends. Given the way they used to invite everybody to their famous parties (Christmas, weddings, etc.), it's a bit odd that the Malones were never mentioned in the first four seasons. Same for Harry Wilson: Kelly's next-door neighbor and friend for years, but never mentioned again. For a lesser extent, Teddy Montgomery qualifies, although Adrianna's past dating record saves the trope from being far-fetched in that case.
* Lydia Rodarte-Quayle in ''Series/BreakingBad'' was a case of this. She's first introduced in season 5A, where she is established as being acquainted with Gus Fring and Mike Ehrmantraut, despite the fact that she was never seen or so much as mentioned in earlier seasons. This is mitigated by ''Series/BetterCallSaul'', which is set before the events of ''Breaking Bad'', and, due to the return of Gus in season 3, gets to explore the early stages of Lydia's business dealings with Gus and Mike.
* ''Series/BuffyTheVampireSlayer'': %% For Dawn Summers, see the memory alteration section.
** In the first three seasons, the monster or woobie of the week or a victim thereof was almost always a student or a teacher who had never appeared or been mentioned, but would sometimes be said to have known Xander and/or Willow for some time.
** Spoofed with Andrew in Season 6. Unlike the other two members of the Trio his character hadn't appeared in the series before, so an incident involving flying demon monkeys attacking the school play was written into his backstory -- however none of the Scoobies can recall the incident, only that he's Tucker Wells's brother (who did appear in the series). This happened because originally Tucker was going to be in the trio but his actor couldn't do it; presumably he would have been the misogynist leader of the group that Warren ended up being, while Warren would be more of the pathetic toady like Andrew.
** {{Deconstruct|ion}}ed in the Season 7 episode "Conversations With Dead People". When a vampire recognizes Buffy he explains that they went to high school together and shared a few classes. Buffy, however, does not recognize him at all, not even when he tells her his name, and it is only after ten minutes of explaining when they met and things they had done together that she remembers who he is. To the end of the episode, he never becomes a close and dear friend from her past, instead remaining a minor acquaintance that she met on rare occasions and had forgotten in the time since then because they had never been very close in the first place. If anything he represents how Slayer duties have left Buffy largely disconnected from people besides her close friends.
* Similarly parodied on ''Series/{{Community}}'' when it was explained that Jack Black's character was a background student who had always been there. After that episode he fades right back into the background never to be seen again.
* Kelly Crabtree in ''Series/CoronationStreet'' -- the first time we ever see her, she's just left her supposedly long time job at the factory that half the other characters work at.
* Sondra, the oldest Huxtable daughter, was added late in season 1 of ''Series/TheCosbyShow'' as being busy attending Princeton, even though dialogue in early episodes indicates that the Huxtables have only four kids. In real life, Sondra was created because Bill Cosby wanted the show to express the accomplishment of successfully raising a child (''e.g.'', a college graduate).
* ''{{Franchise/CSI}}:''
** ''Series/{{CSINY}}'' did this with Don Flack - he did not appear in the series pilot, ''Series/{{CSI Miami}}'' "MIA-NYC Nonstop" but the character was added for the main series, and given they work with Flack every case, it's strange they weren't working with him in that ep. He could've been sick or something, but no one said anything later on in the series' first ep of its own, either.
** ''Series/CSICrimeSceneInvestigation'': In "The Theory of Everything", we learn that there is an insane ConspiracyTheorist woman who comes to police HQ to file charges against extraterrestrials every night, and that Nick is fond of her. This is of course the first time we ever hear of her. [[spoiler:And the last: She's hit by a truck in the second act.]]
* ''Series/Daredevil2015'':
** Averted with this incarnation of Stick, as his time training Matt forms the flashbacks of the seventh episode in season 1.
** Benjamin Donovan, the crooked lawyer overseeing Wilson Fisk's affairs while Fisk is in prison during season 2, was not mentioned at all during the first season.
** Lampshaded in season 2. When helping Matt with his tie prior to Grotto's funeral, Karen mentions having a brother, who has never been so much as discussed up until this point. Matt is surprised as Karen has never mentioned having any siblings before, to which Karen simply replies, "[[YouDidntAsk You never asked]]."
* ''Series/TheDefenders2017'': Only two of the Hand's five leaders were introduced in prior series: Madame Gao through ''Series/Daredevil2015'' and ''Series/IronFist2017'', and Bakuto in ''Iron Fist''. The other three - Alexandra, Sowande, and Murakami - are this trope. While Bakuto and Madame Gao made cryptic references to Alexandra's existence during ''Iron Fist'', Murakami is an egregious case as Stick mentions that Murakami pulled the strings behind Nobu's operation in ''Daredevil'', yet Nobu at no point gave any indication he was a subordinate to a Finger. Especially since Nobu was the one assisting Madame Gao in doing business with Wilson Fisk.
* Arguably the case with Gretchen Witter in ''Series/DawsonsCreek''. We first see her in season four, which is somewhat fair since she has been away at college for years; what edges her close to this is that we have never even heard about her before, despite being Pacey's sister and (especially) Dawson's childhood crush. Given the nature of the show and characters, it is a bit of a stretch that no one mentioned her.
** Pacey had mentioned having older sisters before.
* Happens in ''Series/{{Degrassi}}'' sometimes, in the most recent seasons with Dave and Imogen. Partly justified since it is a school setting, so presumably the person was a student at Degrassi but never was friends with the main cast.
** Used to decent effect in the case of Imogen, where she explains to Eli that she saw all the things he'd been going through over the last year, but Eli never saw her and instantly freaks out, accusing her of being a stalker.
* ''Series/ADifferentWorld'' actually manages to do this in the first episode. Denise already knows the character of Whitley, and her personality and habits are treated as if they are already established. She meets every other character for the first time. Since this show is a spin-off, an easy assumption to make was that she first showed up in an episode of ''Series/TheCosbyShow'', but that isn't the case. Justified since it wasn't actually Denise's first day on campus. Denise was a sophomore during the first season of ''A Different World'', her freshman year took place the year before while she was still on ''The Cosby Show''. It was assumed that Denise met Whitley off-camera during her freshman year.
* The second series in the ''Series/DoctorInTheHouse'' franchise, ''Doctor at Large'', introduced ProfessionalButtKisser Lawrence Bingham, who is implied to have gone through medical training at St. Swithin's with the main cast and whom the other doctors know well enough to thoroughly detest from the start. However, he was never so much as mentioned in the first series, ''Doctor in the House'', despite winning the surgery prize in his final year ahead of main characters Michael Upton and Duncan Waring.
* ''Series/DoctorWho''
** Inverted with River Song, who in [[Recap/DoctorWhoS30E8SilenceInTheLibrary "Silence in the Library"]] walks up to the Doctor and begins chatting with him as if they're old friends. The Doctor, however, has never met her before -- turns out that, thanks to the TimeyWimeyBall, he's meeting her out of sequence.
** In "Let's Kill Hitler" Amy and Rory's old friend Mels suddenly shows up to the Doctor's confusion -- he doesn't know who she is, as she wasn't at Amy's wedding because she "doesn't do weddings". [[spoiler:She's actually River Song's previous regeneration. Wibbly-wobbly, timey-wimey.]]
* The Dingle family were introduced into ''Series/{{Emmerdale}}'' as an infamous bunch of rowdies known to the entire village, despite never being mentioned in two decades of the soap's previous history.
* ''Series/FamilyTies'' has several episodes in which characters are introduced as being childhood best friends or so-and-so's favorite relative yet they have never been shown or mentioned before and almost always never referenced again. One notable example was when Alex was given a black friend and the family spent an entire scene explaining that the two were best friends who have been competing with each other since they were kids.
** Another example was Alex's friend Greg from the two-part VerySpecialEpisode "A, My Name Is Alex". Even though he was never shown before this episode, he was one of Alex's best friends since childhood, and Alex was so distraught over his death that he needed to see a therapist.
* Subverted on ''Series/{{Farscape}}''. In the Season 3 finale, "Dog With Two Bones", Noranti appears for the first time. It's stated that in-between episodes, the crew rescued some refugees and Noranti apparently decided to stay. Anyway, whenever Noranti begins to talk about the crew's current problems, everyone else remarks with a "Who is that?" response. Viewers didn't even learn her name until the end of the third Season 4 episode. Given her ability to affect memory with her potions, Noranti could well have been lying about the whole business.
* When writing the film ''Serenity'', a follow up to the quickly canceled ''Series/{{Firefly}}'' intended to show a condensed version of his plans through roughly the show's first 2 seasons, Joss Whedon created the previously unmentioned jack-of-all-trades Mr. Universe to facilitate plot developments that he didn't have the time to develop more naturally anymore.
** [[AllThereInTheManual It was mentioned somewhere]] that Mr. Universe was a friend of Wash's, possibly explaining his lack of an existence previously as Mal never having had any reason to talk to the guy, only being peripherally aware of him. Wash is the one who suggests going to see him, though he says it in way that suggests he expects everyone else to know who he's referring to.
* Frasier's brother Niles on ''Series/{{Frasier}}'' had never been mentioned on Frasier's previous series ''Series/{{Cheers}}''. Lampshaded when Sam Malone from ''Cheers'' visited Frasier and told Niles he was never mentioned by his brother. At least in this case it's made clear that during ''Cheers'' Frasier was estranged from his family besides his mother, and had even told the cast of Cheers that his father was dead (something Sam also asks about).
* ''Series/{{Friends}}'':
** All the celebrity guest stars easily fall under this trope. For instance, Brad Pitt's character, who was supposedly a close friend of Ross and Monica, but was never mentioned before or since, wasn't in attendance at their wedding, etc.
** Phoebe says she has a roommate Denise who has always been there if only the gang would listen to her. WordOfGod says that Denise didn't actually exist. It was just a weird Phoebe quirk the writers [[ThrowItIn tossed in]] [[ForTheFunnyz for comic relief]].
* ''Series/GameOfThrones'':
** Dolorous Edd is suddenly part of Lord Commander Mormont's group, although the scene from the book where he meets up with them is cut.
** Roose Bolton. The Bolton sigil is seen at Robb's war council in Season 1. He was planned to be included in a montage of the Stark bannermen receiving their summons to Winterfell, which was scrapped for being far too expensive. The actor was cast in Season 2.
** The Tullys of Riverrun show up around the same time, and we're told they were part of Robb's war effort just offscreen until now. Edmure is actually introduced being chewed out for not following a (badly communicated) plan in a battle that hadn't previously been mentioned.
*** In the books, he's introduced and discussed well before this time, and you see the scene from Catelyn's point of view where he elects to engage Tywin, although Catelyn displays some misgivings. The significance of how this impacts the war effort is deliberately downplayed until later so as to leave the consequences (Tywin being stymied at heading west and therefore being available to come to King's Landing to defeat Stannis) as a surprise (to the reader, and to most of the characters). In the show Tywin wasn't present and it's an insignificant skirmish that had no effect on anything other than a half-baked strategem against The Mountain that was never mentioned before or again.
* Somewhat subverted on ''Series/GreysAnatomy'' with Jim Nelson, aka "Shadow Shepherd", the hospital's other neurosurgeon, who isn't mentioned or shown until Season 5 despite having worked there all along. It's only when Derek Shepherd temporarily decides to quit operating that Nelson is shown, due to him supposedly not being as good a surgeon as Shepherd. Also a possible lampshading of how self-involved the main characters are.
* Chachi is introduced this way in ''Series/HappyDays'' with The Fonz delivering the line, "You all know my cousin Chachi," and everyone else replying in the affirmative even though he's never been seen or mentioned before.
* ''Series/HomeAndAway'''s latest school principal Martin Bartlett first appeared in 2008, but when Kirsty Phillips, who attended the school during her original 2000-2005 stint, returned a few months later she mentioned that Martin had been one of her teachers.
** Similarly, character Travis Nash (1995-1999) first appeared as a witness to the death of Laura Bonnetti with all the regular cast already knowing him - he was another local who had always been around but just never seen on-screen before.
** This happened with an entire group: The River Boys first appeared in 2011, despite living in a region that is not far from Summer Bay. This is largely because they are a NoCelebritiesWereHarmed take on the Bra Boys, who were largely unknown outside of their home suburb of Maroubra (despite several well-known members) until 2007.
* ''Series/HouseOfAnubis'' introduces the character of Willow in season three, a character everyone in Anubis House knows but the audience doesn't. This is justified in that the main characters were hardly ever shown interacting on screen with anyone not from Anubis House, and only the important events of each season's year were shown to the audience. It's possible Willow- and by extension, her house Isis House- had existed all along, but just wasn't relevant until the third season.
* ''Series/HowIMetYourMother'' makes this trope part of its regular routine, as the show is framed as the recollections of an UnreliableNarrator; Ted is regularly shown to remember things that are out of order or skips over events and people that he deems unimportant to that particular story. A lot of events and characters are only mentioned when they actually become relevant. Possibly to be done intentionally with the mother, as the character has apparently been cast since the first season, and has been filmed in the backgrounds of the events of the show.
* Every school kid who ends up in the plot for ''Series/ICarly'' except [[MrExposition Wendy]], [[BigFun Gibby]] and Rebecca Berkowitz. Some of the teachers, too. For some reason, most of the guys (who are usually a love interest) are introduced as seniors, which kinda makes it creepy in the couple seasons when they hit on Carly and Sam who haven't even reached the 'growth' stage of puberty yet. Then they give ChuckCunninghamSyndrome to them all anyway. It's averted once, where Brad is looked over as a new intern to drive the plot of "iHire an Idiot" then gets re-introduced in "iOMG" in a way that makes it obvious he's a NewTransferStudent. The most famous example is Sam's identical twin Melanie who Carly and Spencer seemed to know was at boarding school. Freddie thought she was just Sam but her existence was confirmed.
* ''Series/IronFist2017'': The ''Bulletin'' reporter that interviews Ward Meachum is Jennifer Many, who appears to be a veteran reporter, but was never seen nor mentioned in any of the ''Bulletin'' scenes in ''Series/Daredevil2015''.
* ''Series/{{JAG}}'': In the 7th season we first meet Sturgis Turner. He and Harm went to the Naval Academy together and were apparently quite close friends. The writers also make several continuity references just to shoe-horn him in.
* ''Film/KaizokuSentaiGokaigerVsSpaceSheriffGavanTheMovie'' plays with this, by having Marvelous (Gokai Red) reveal that he has met Retsu Ichijouji a.k.a. Series/SpaceSheriffGavan when Marvelous was still young; the flashback also implies that the Space Police are also dealing against the Zangyack invasion around that time. [[Series/TaiyouSentaiSunVulcan This]] [[Series/TokusouSentaiDekaranger wasn't]] the first time that ''Franchise/SuperSentai'' and the ''Franchise/MetalHeroes'' are teased to take place in the same universe.
* {{Lampshade|Hanging}}d with Yukina in ''Series/KamenRiderFourze''. It is presented as though the other characters already know her when she makes her introductory appearance, but Ryusei confusedly asks "Who?" immediately after seeing her.
* In ''Series/TheLegendOfWilliamTell'' Vara breaks back into the Citadel in one episode to look for her nurse, who she loves dearly and who's always taken care of her. It's neither the actress nor the character who was her nurse in other episodes.
* This is true of several characters on ''Series/{{Lost}}'', including Ethan and Arzt, but Nikki and Paulo are easily the best example. Introduced out of nowhere at the beginning of season three, the dynamic duo were apparently survivors of the crash. While random {{Redshirt}} characters regularly pop in and out, Nikki and Paulo began chumming with the main characters, going on adventures, and in general trying to fit in when they had obviously never been there before. They quickly became the most hated characters on the show, and showrunners Damon Lindelof and Carlton Cuse admit that they were a big mistake (but still regularly joke about them). The pair's story climaxes halfway through the season, when a flashback episode retcons them into various scenes, interacting with old characters, and making discoveries. The episode ends when Nikki paralyzes Paulo with a spider that paralyzes him with its venom (don't ask) and Nikki herself is then bitten by another spider (WordOfGod says it was the smoke monster in disguise). Both are then buried alive because they looked dead.
** ''Series/{{Lost}}'' plays with this trope a bit. Sawyer often refuses to accept the existence of new cast members, asking them "who the hell are you?" Arzt and Frogurt were vocally annoyed that the main characters didn't think about them. And Ethan was a spy for the Others who was ''meant'' to act like a normal 815 survivor, so the odds are that if he was, he probably would've got a little bit of face time anyway.
** Lost justifies this in that there are about 40-odd survivors of the crash, most of them extras, so they can easily get away with this. Ethan is only introduced in one of the early episodes anyway- the cast ''don't'' remember him, but ignore that because they have all only just met.
** Neil "Frogurt" is an aversion, however; though he does step in out of nowhere, he had already been mentioned a few times in season two and the mobisodes, so he was already known among both the fans and the characters.
** Part of the reasoning behind Nikki and Paulo's existence was that the show had declared forty-something survivors from the plane crash in the pilot episode. Since they were nearly always seen as background extras with no lines (with the exception of Rose, and nominally Scott and Steve), a frequent fan question was "What do these other people do?" Nikki and Paulo appeared to be a (perhaps somewhat tongue-in-cheek) attempt by the writers to respond to that curiosity. That said, they are used to clear up a number of dangling plot threads, like the case with the gun that the other characters found in the first season.
*** It seems entirely unrealistic that people would have remained anonymous to the main group past a week or two. 40ish people is about the size of two average college classes....who spent months together being in close proximity pretty much 24/7, and relied upon division of labor based upon skill-sets just to survive. Pretty much everyone would know each others' names, and would definitely know each others' faces.
* In many, many episodes of ''Series/MacGyver1985'', an old friend or girlfriend shows up in need of [=MacGyver=]'s help, but it's never someone he saw fit to mention before or ever again. He must have a lot of Facebook friends these days.
* In the early years of ''Series/MadAboutYou'' Paul's best friend Selby is a major supporting character. After Selby get Brother Chucked the role of "Paul's friend and confidant" got taken by Paul's never-before-mentioned but buddies-since-childhood cousin Ira.
* Iola Boylan on ''Series/MamasFamily''. In the syndicated episodes, she's Thelma's next door neighbor/sidekick and has been for years. She's never so much as mentioned in the previous Creator/{{NBC}} episodes. The entire cast of both versions can be considered under this trope, since the original Mama sketches on ''Series/TheCarolBurnettShow'' only featured Thelma (Vicki Lawrence), her daughters Eunice (Burnett) and Ellen (Creator/BettyWhite), and Eunices's husband, Ed (Harvey Korman).
* ''Series/{{Merlin|2008}}'':
** The writers take advantage of a year's TimeSkip between series three and four to introduce Arthur's uncle Agravaine as though he's been present in the kingdom all along. Even though he's never been mentioned before, there are lines like: "I promised your mother I'd always be there for you," and "I've known him since I was a child," though there's no indication where he's been all this time.
** A similar thing happened with Guinevere's brother Elyan and Morgana's half-sister Morgause, even though these examples were partially justified in that the former siblings were estranged for years, and the latter were deliberately kept apart.
* ''Series/TheMusketeers'': [[spoiler:Louis']] brother shows up in Season Three. Everyone knows him, including people banished or otherwise gone from Paris for longer than the show's been running.
* ''Series/MyNameIsEarl'': When Earl encounters his friend, Frank Stump, in prison, the episode (one long flashback) explains that Frank and another new character, Paco, were the original occupants of Earl's trailer, and that they and the Hickey brothers used to live all four together. Plus, Earl's El Camino is revealed to actually be Frank's. The same time frame was seen in many other flashbacks, and Frank wasn't in any of them.
* Part of the ''Series/MysteryScienceTheater3000'' episode ''[[Recap/MysteryScienceTheater3000S08E21TimeChasers Time Chasers]]'' is set in an alternate timeline where the show's host, Mike Nelson, is replaced by his brother Eddie (who was never mentioned in previous episodes).
* ''Series/{{NCIS}}'': Dwayne Pride of ''Series/NCISNewOrleans'' is introduced in the 11th season as a longtime old friend of Gibbs--who has ''never'' been mentioned before, despite Abby shrieking with joy when she sees him, [=DiNozzo=] and [=McGee=] telling newcomer Bishop that "stories about them are legendary", and Gibbs himself telling the team that "I've known him for 30 years", and it being revealed that it's ''he'' whom Gibbs got his elevator trick from. Similarly, the latter show's Dr. Wade is apparently an old friend of Ducky's, even though he's never mentioned her before either.
* Jessica and Taylah were randomly introduced as the [[TheBully school bullies]] in ''Series/{{Neighbours}}'', and everybody on the show treated them as though they has always been there, bullying other students and harassing the main teen characters, despite the fact that, story-wise, they clearly hadn't been.
* ''Series/NightMan'' does it with ''most of the main cast'' (except for the main character) when they moved production to Canada in-between seasons. We're expected not to notice.
* ''Series/{{NUMB3RS}}'': Colby Granger and Megan Reeves both appear in the Season 2 premiere with almost no explanation. They do at least get a few nods to the idea that they really ''haven't'' been around long (Megan has to be introduced to Larry, and Don and David have a conversation about Colby being fresh from the army).
* Taylor Townsend of ''Series/TheOC'' is perhaps the most successful example. Taylor first appeared at the start of the third season (in the aptly-named "The Shape of Things to Come") as an enemy of Marissa, yet, according to the other characters, had apparently been around for years and had even attended the same elementary school as Summer and Marissa, according to a flashback the following season. The character (and actress Autumn Reeser) proved so popular that fans were willing to overlook her origins, and the show even indulged in a little LampshadeHanging when Summer referenced a scene that had happened long before Taylor's creation:
-->'''Taylor:''' You didn't see me but I was there, and I remember that geek was totally in love with you.
* In the final season of ''Series/{{The Office|US}}'', it was revealed that Dwight has a sister and a brother; while the brother had been previously brought up in a ChristmasEpisode, there was never any indication of the existence of the sister. Their sudden prominence is largely because the episode that showcased them was a [[PoorlyDisguisedPilot backdoor pilot]] for a proposed SpinOff centered around Dwight, and the creators likely wanted to flesh out his potential supporting cast.
* ''Series/OurMissBrooks'': Bones Snodgrass is introduced in the episode "The Yodar Kritch Award". He was never before seen or mentioned by name, in spite of being the [[SuspiciouslySimilarSubstitute brother]] of recurring character Stretch Snodgrass.
* ''Series/OrangeIsTheNewBlack'': Stella, a heavily tattooed Australian model who stands around naked in the bathroom, has apparently been at Litchfield this whole time, but no one noticed until episode 6 of Season 3.
* In ''Series/PartyOfFive'', Sarah Reeves pops up in second season, working a summer job at Salingers, yet she goes to the same school as Bailey and Julia, and is in many of Julia's classes, somehow without getting a previous mention.
* ''Series/PennyDreadful'': At the beginning of the third season Victor Frankenstein's friend Dr. Jekyll is introduced, and almost immediately chews Victor out for having disappeared and not contacted him for five years. Given Victor's private disposition, obsessive focus on work, and the [[FrankensteinsMonster nature of that work]], it's not entirely surprising that he would never have mentioned or contacted his best friend.
* Nothing is known about ''Series/PersonOfInterest'''s Detective Petersen other than that he works for HR and enjoys shooting people. Miller, the other underling introduced in the same episode, is treated as a random mook, yet Petersen seems to go some way back with Simmons and is recognizable to Fusco. However, he's completely new to the viewer.
* Beautifully played with on ''Series/{{Reign}}'' when the fourth season introduces Catherine's never talked of older daughter Leeza. During a family fight, Claude explains why viewers haven't heard of her before: Leeza is just so damn boring and dull that the moment she left French court, the rest of the family never found any reason to mention her at all.
* On ''Series/{{Revolution}}'', characters frequently run into old friends or enemies from the past who'd never been seen or mentioned in the show before. Sometimes this is averted by having the character introduced in flashbacks before they show up in the present day (Priscilla) while sometimes when it's played straight, the character's significance is explained through flashbacks after the fact (Jeremy, Emma).
* A late episode of ''Series/RobinOfSherwood'' introduces Martin, the young nephew of the Sheriff of Nottingham. Supposedly he's been living with his uncle at the castle all along, but has never even been mentioned before.
* If you accept that ''Good Morning Miss Bliss'' is part of the same continuity as ''Series/SavedByTheBell'' then Jesse Spano and Kelly Kapowski. The former lives next door to Zack and has been friends with him since childhood, while he has been trying to go out with the latter for as long as she can remember. That said, most people don't accept the two as the same continuity, since the entirety of the school magically moves from Indiana to California.
* Played with on ''Series/{{Scrubs}}''. Kim Briggs had been at Sacred Heart for years, it's just that J.D. couldn't see her because all women wearing wedding rings are flat-out invisible to him. The kicker is when all married women within earshot are asked to take off their rings for a moment. Suddenly J.D. is surrounded by dozens of women, including Gift Shop Girl from earlier in the series. (J.D. assumed that she had died and sent flowers to her family. Flowers that he bought from her at the gift shop.) We're even treated to fake flashbacks of important events in the series' past where Kim was photoshopped in a la ''Film/ForrestGump'' to make it look like she'd been there all along.
** In her first episode they also added an extra bit to the opening credits where she fixes the backwards x-ray and tells the camera that it's been [[LeaningOnTheFourthWall bugging her for years]]
* The third season premiere of ''Series/SesameStreet'' begins with a long sequence on the street, with child voice-overs knowing who everybody is, including humans (Luis, Molly, Rafael) who make their debuts in the opening scene.
* ''Series/{{Shameless}}'' loves this trope. Gloria and Dominic Meak are introduced as new characters in series 9, but it was implied that they had actually been on the estate the whole time (since rather than being 'introduced' as brand new, they simply walked in and were acknowledged and treated as if they were just ordinary regulars as usual).
** The Maguire Family does this with Shane and Mickey. Shane is introduced and named towards the end of series 3, and Mickey is seen from the start in series 4. But neither of them ever officially appear, or are even named, prior to their scattered first appearances. And when they first appear, they are never ''never actually introduced''. The show treats them as if they had always been around, and it's largely implied that they were the early Maguire brothers seen in the earlier series. Although why they would go from mindless, unreferenced thugs with no dialogue, straight to main big mouthed characters who are named on screen at every opportunity, is probably because the show was looking to promote the Maguire Family to main cast, and thus needed to give its members more substance and personality.
* Tony B. in ''Series/TheSopranos'', which did this nearly once a season. Ritchie Aprile and Ralphie are two other notable examples. In each instance, the justification was that they were in prison and the guys didn't want to talk about them.
* Security Chief Tony Verdeschi in ''Series/{{Space 1999}}''. His inclusion as a regular character and member of Commander Koenig's senior staff at the beginning of the second season is taken in stride by all the other characters despite no explanation of how he got there, especially in light of [[ChuckCunninghamSyndrome the contemporaneous disappearance]] of several characters from the first season.
* ''Series/StargateSG1'': Cameron Mitchell. He's never mentioned before Season 9, and since the Season 8 finale was screwing with time, [[WMG/StargateSG1 you have to wonder where he came from...]] According to {{Word of God}}, he was supposed to be introduced during the big Antarctica battle in Season 7 instead of just being retconned into it later.
** The trope is played with in "The Fifth Man." SG-1 suddenly has a new member, a Lt. Tyler, and the team acts like he's been with them for a long time. Then some of them get back to Earth, and discover that no one else at the SGC has ever heard of Lt. Tyler. [[spoiler: It turns out he's a member of an alien race that excretes a chemical that creates false memories and illusions in others so they will think he's a friend.]]
* From ''Franchise/StarTrek'':
** The Cardassians are introduced in the ''[[Series/StarTrekTheNextGeneration The Next Generation]]'' season four episode "The Wounded," where it is explained that it has been only a year since the end of the long, costly war between the Federation and the Cardassian Union. However, this information means that the first two years of the show occurred during a war that was never seen, heard or experienced. Just where, exactly, was the flagship of Starfleet while the rest of the fleet was engaged in active operations? And how is it that Chief O'Brien is a veteran of the Cardassian War when he's been on the ''Enterprise''-D since TNG's first episode? Was the ''Enterprise'' fighting in the war between episodes and nobody bothered to mention it, or are we supposed to assume that the first four seasons all took place in a single year despite all indications to the contrary? Admittedly there are a few hints that while to the Cardassians it was a major war, to the Federation it was a [[ButForMeItWasTuesday basically just a regional conflict]], albeit an unusually long and bloody one for the period. If O'Brien served, presumably the conflict went back to before the Enterprise-D was commissioned and he was posted there.
** The TNG episode "[[Recap/StarTrekTheNextGenerationS5E14Conundrum Conundrum]]" featured an aversion, as the crew is hit by some sort of [[IdentityAmnesia amnesia beam]] just prior to the plot and "Commander Macduff" introduces himself while the crew is trying to sort themselves out.
** Even Ben Sisko has a bit of this, as he's introduced in the ''[[Series/StarTrekDeepSpaceNine DS9]]'' pilot as an officer on the ''Saratoga'' during the Battle of Wolf 359. This one's at least justified, since we never actually see the battle in "Best of Both Worlds", only its aftermath.
** ''Series/StarTrekVoyager'' had an episode Lyndsay Ballard, a crew member who had died and been resurrected by aliens, returns but no longer fits in; she had never been seen or mentioned before. This despite it being a ''Star Trek'' series, the {{Trope Namer|s}} and {{Trope Maker|s}} of the [[{{Redshirt}} disposable one-shot crew member]] phenomenon. It's not like there's any lack of ''established'' dead or missing crew members to bring back. In fact, Ballard bears enough similarity to Ahni Jetal (see the "in-canon" examples) that it's likely that they couldn't get Jetal's actress back or something. Shoulda made 'em the same character anyway; if there can be ''three'' Tora Ziyal's and nobody cares...
*** Amusingly played with by the minor character Joseph Carey, who was a regular in the first season before disappearing from the show, except for flashbacks and time hops to the period of the first season. He then showed up again in the last season without comment, just in time to be killed off. A common fan theory is that the writers forgot they hadn't actually killed him off yet.
** In both ''Film/StarTrekIntoDarkness'' and his debut episode ''Space Seed'', each set in different continuities, Khan Noonien Singh is established to be a genetically / eugenically engineered Ubermenschen despot from the late 20th / early 21st century, the most prominent of several in fact-, who ruled various nations across the globe, who partook in a destructive global conflict known as the Eugenics Wars. Despite this, nobody on the crew of the ''Enterprise'' has even heard his name (including the ''ship's historian''), and they are only vaguely aware of what must have been a fairly major era in world history. Especially noticeable since they seem fairly knowledgable of several other historical figures, yet the guy who sounds like he was a latter-day Napoleon or Julius Caesar is a mystery to them. A possible justification could be that most knowledge of the Eugenics Wars was lost in WorldWarIII (which occurred not too long afterward), making Khan a somewhat obscure figure.
** ''Series/StarTrekDiscovery'' is going this route as well, with the protagonist Michael Burnham being a human who was adopted by Spock's parents, yet Spock's step-sister has never been mentioned in any previous material. [[spoiler:Played with in a rather clever way, since by the end of the pilot Michael's racked up a sizeable list of crimes, including mutiny and causing war to break out between the Federation and the Klingon Empire, and she's sentenced to life in prison; understandable that Spock wouldn't mention her.]] There's also the fact that Spock and Sarek weren't on speaking terms at the time, as Spock chose to enlist in Starfleet instead of going to the Vulcan Science Academy and then joining the Vulcan Expeditionary Group ([[spoiler:Sarek also feels guilty for choosing Spock, when he was forced to pick either Spock or Burnham for a spot in the VEG, a choice that, in the end, was futile]]). Oh, and neither Burnham nor Spock mention Spock's half-brother Sybok.
* In the second season of ''Series/TeenWolf'', Isaac, Erica and Boyd suddenly show up, and the other teenagers act like they've gone to school with the three of them for years, even though they're very clearly not present in the first season. Suddenly, Isaac is on the lacrosse team like he's always been there, Jackson knows that Isaac's dad is [[AbusiveParent abusing him]] because they live across the street from each other, and it's common knowledge among the students that Erica is epileptic.
* In ''Series/ThatsSoRaven'', even though dialogue indicates that Alana and Raven have been rivals since elementary school, Alana isn't introduced or even mentioned until Season 2.
* ''Series/TorchwoodChildrenOfEarth'' plays it straight with Jack's never-seen-or-mentioned-before daughter and grandson. It is stated that she asked him to stay away due to [[ReallySevenHundredYearsOld his condition]].
* Used quite a bit in ''Series/TwentyFour'', for example, the fourth season which introduced Curtis Manning it's revealed that Jack knows him and has worked with him before. Since Jack was let go from CTU following the events of the previous season, that means that Jack would have had to work with him prior to the third season. Justified in most cases however, since the season only takes place within a [[ExactlyWhatItSaysOnTheTin 24-hour period]] and several months if not years pass in between each one, it means that there is time that could be accounted for all these moments during those lengthy gaps.
* ''Series/TheVampireDiaries'':
** Rebekah is stated to have been with Klaus and Elijah in 15th century England despite her role not even existing at the time.
** The Founders Council is apparently much bigger than originally thought. We don't know this until season 3 when new members like Meredith Fell and Brian Walters start to show up. And then, in season 4, [[spoiler:a whole bunch more come out of nowhere just to be killed off]].
* Helen's sister Casey was added to the cast in season 6 of ''Series/{{Wings}}'' despite having never been mentioned before. Helen had mentioned a sister in a previous episode, but that sister was named Lorraine and was clearly a different person from Casey (who is implied to be her only sister), making this a {{Retcon}} as well.
* This was the standard way to introduce new characters in ''Series/TheXFiles'', to the point that the show was almost an "old friend of Mulder or Scully of the week" show in addition to a MonsterOfTheWeek one. For bonus points, they were usually introduced as a friend, the relationship played up for several scenes, and then killed off by the aforementioned monster. The trope was especially prevalent in the early seasons before longer plot arcs were firmly established along with longer-lived secondary characters.

* When you download a new song to an Apple device while it's in shuffle, the device will sometimes insert the song into ones you've already played, even then the particular song wasn't played.
* Music/BraveSaintSaturn's first album was a RockOpera about fictionalized versions of the band's three members as astronauts. Their second album was a sequel, but a new member (Andy Verdecchio) had joined the band by then, so the liner notes wrote about him as a crew member as if he had been on the mission from the beginning. For the third album in the series, Andy was just as abruptly written out of the crew--this time, he was a cosmonaut on a completely different spacecraft.
* Music/{{Queen}}: Freddie Mercury (1946-1991) didn't give interviews too frequently, but he did grant at least ten per year since he became famous in '74. Very often, he was asked about his favorite singer(s) and answers used to include [[Music/LedZeppelin Robert Plant]] and, depending on the era and occasion, people like Music/MichaelJackson, Music/ArethaFranklin, Montserrat Caballe, etc. His band mates, his former girlfriends and boyfriends, biographers (official and unofficial), people who worked with him (producers, engineers, guest musicians) were also asked about Freddie's favorite singers and more and more names came including Music/{{Prince}}, Music/DavidBowie, etc. [[Music/FreeBand Paul]] [[Music/BadCompany Rodgers]] had never been mentioned as one of his influences until late 2004 when Brian May and Roger Taylor decided to go on tour with him as "Queen + Paul Rodgers." Then, he'd suddenly become "Freddie's favorite singer" and had apparently been all along. When the partnership ended, Freddie's alleged admiration for Mr. Rodgers was never mentioned again.
* "[[WesternAnimation/RudolphTheRedNosedReindeer But do you recall/The most famous reindeer of all?]]" Back when the song was written, this trope was in full effect, as Rudolph was created by the songwriter. Several Creator/{{Rankin Bass|Productions}} specials and light-up lawn decorations later, it could be argued that Rudolph ''is'', in fact, the most famous reindeer of all - or at least the most distinctive, since all the other reindeer have no real character traits. The line in the song itself is pretty funny--the singer takes for granted that "You know Dasher and Dancer...." So why would there be any question of the listener recalling the most famous one?
* Tag Team's first single "Whoomp! (There It Is)" (which was also the first track from their first album) has the line "Tag Team back again".
* Music/VanillaIce's first hit "Ice Ice Baby" has the line "Ice is back with my brand new invention". Somewhat justified in that the song was originally the B-side to "Play That Funky Music" (so he was "back" from the A-side).
* The Music/BackstreetBoys' "We've Got It Goin' On" derives its title from a line in the chorus, "We've got it goin' on for years". While this line would definitely ring true over 20 years later, when it was released that wasn't quite the case, as it was their debut single.

[[folder:Professional Wrestling]]
* A characteristic of Wrestling/{{TNA}}, [[SignatureStyle particularly whenever Russo has the book]], especially in 2007. The most obvious cases being Wrestling/SamoaJoe's girlfriend, [[{{mooks}} the entire Latino Nation]], [=SoCal=] Val, Matt Morgan, Wrestling/{{PAC}} and Peyton Banks. A sufficiently hardcore pro wrestling fan might have known a few of these people already, indeed many of the live audience members seemed to, but to those who only watched TNA they just showed up with no fanfare yet were put into positions of focus.
* When Wrestling/{{CMLL}}'s deal with Wrestling/RingOfHonor became official, three luchadors were sent by the former to compete in the latter's World Six Man Tag Tournament, the legendary Último Guerrero, the up and coming Hechicero and, as Kevin Kelly called him, "our old pal Okumura". Again, a hardcore pro wrestling fan probably did know Shigeo Okumura, but there wasn't any reason for anyone just watching ROH to know who he was.[[/folder]]

* ''Radio/AdventuresInOdyssey'' introduced the eccentric mailman Wooton Bassett this way in "Welcoming Wooton," and to a certain extent, the entire Washington family (most notably Ed) in "The Toy Man." The latter was a little jarring, given that Ed Washington went from not being a character to the conveniently dilemma-solving manager of the new Whit's End in a single episode.

[[folder:Tabletop Games]]
* ''TabletopGame/{{Warhammer 40000}}'' has a rather extreme example with the Necrons and their C'Tan masters, who when introduced were not only [[GreaterScopeVillain major parts of the galaxy's backstory]] and indirectly responsible for some pretty significant things (namely the transformation of the Warp and its denizens from pure ChaoticNeutral to malicious ChaoticEvil, and the creation of the Orks and the Eldar), but had managed to hide on numerous planets undetected and undiscovered for approximately ''[[TimeAbyss sixty million years]]''. They are also apparently ancient enemies of the Eldar, despite no Eldar ever mentioning them before.
** Also standard procedure whenever new characters and units get added to the game. Some of them manage to avert it, particularly in the case of new Tau units (as they, unlike most other factions, are still regularly producing new technology), but it's more common for the trope to be played straight instead. When this happens, expect older pieces of lore to receive a {{Rewrite}} in order to include them. Probably the most dramatic is the Swarmlord, who when introduced was suddenly present and in command for ''every'' decisive battle in the Tyranid wars.

* In ''Theatre/HenryIVPart2'', Pistol is introduced as a long-established member of Falstaff's criminal/military crew, despite not having even been mentioned in Part 1.
* In ''Theatre/{{Macbeth}}'', Macbeth hires two murderers to kill Banquo and Fleance, but three show up to do the deed. Since the Third Murderer is of no real consequence, this may be a case of textual corruption. Alternately, [[Creator/WilliamShakespeare Shakespeare]] just needed a reason for the murderers to [[AsYouKnow talk about what they're doing rather than just doing it]], and a [[TheWatson new guy who doesn't know what's happening]] is a [[MrExposition convenient device]]. Another reading of it is that the third murderer is Macbeth himself in disguise, as he is so paranoid he has to see the act being done before his own eyes. Finally, there is at least one performing group whose interpretation of the above is to have the third murderer kill off the first two. Dead men tell no tales.

[[folder:Theme Parks]]
* Ride/DisneyThemeParks:
** Walt Disney World's 2010-2014 expansion of Fantasyland (aptly dubbed New Fantasyland) is treated this way in the official tie-in material, explained as always having been there, though unbeknownst to us due to a recently-broken curse placed upon it.
** A similar mythology was used for the opening of Mickey's Toontown in Disneyland: the "neighborhood" had been there since before the opening of the park, but humans weren't allowed in until 1993.

[[folder:Video Games]]
* Grimm in ''VideoGame/AceCombat5TheUnsungWar'' is introduced this way, where halfway through the fourth mission he comes in out of nowhere, announces he's taking a spare plane up to help you defend the base, and the game treats this like some sort of shocking development while a first-time player is wondering, "who the hell is this?". Fortunately, it happens early enough in the game that it isn't too jarring.
* In ''VideoGame/BaldursGateII'', it's actually the main character's own choice if they recognize people they might actually have met in the first game or not. Interestingly, among the dialogue options there is usually also "Shouldn't you be dead?" This is somewhat necessary, of course, considering the non-linear nature of the ''Baldur's Gate'' games. It's actually possible to play the first game without ever meeting some of those characters, or without having them join your party, depending on the decisions the player makes.
* Prior to his appearance in ''VideoGame/BatmanArkhamKnight'', Jason Todd was absolutely unmentioned in the first two games and companion media, not even mentioned in the database entries and the Batcave DLC we see in ''City'' was missing the iconic Robin display monument. About the only reference was an oblique comment ("Didn't I Kill You?") in the Joker's Funland challenge DLC. Knight has several flashbacks dealing with Todd before TheReveal. Why is this prominent? [[spoiler: It's because Jason Todd is the very same Arkham Knight who serves as the titular [[TheDragon Dragon]] to Scarecrow.]]
* ''VideoGame/Battlefield4'' manages this with an ''actual'' recurring character, CIA agent Kovic. He's supposed to be one of the two people who were interrogating Blackburn about his actions in ''VideoGame/Battlefield3'', but there's next to no recognition possible. You can't recognize him by name because [[NoNameGiven the previous game never saw fit to ever tell you it]], and you can't recognize him by his personality or manner of speaking because [[FlatCharacter his entire personality back then]] could be summed up as "you're a lying liar who lies, the Russians are the real bad guys". He at least gets off [[TheOtherDarrin better than]] [[spoiler:Dima]], though, by at least keeping the same face and voice.
* ''VideoGame/BillyVsSNAKEMAN'' has Sue. Allegedly, she's in your party from the start, but she doesn't appear on your ally list until you've beaten her in a game of TabletopGame/{{Mahjong}}.
* Sofia Lamb, the BigBad of ''VideoGame/BioShock2'' is established in the latter game as having been a major opponent of Andrew Ryan during Rapture's early history, having her following/cult of ideals diametrically opposite to those of Ryan and having ''public debates with the latter'' despite having never having been mentioned in the previous game (Sinclair and Alexander at least had their names mentioned once or twice). This is slightly justified by her having been kept in Ryan's secret prison during Fontaifne's rise to power while Ryan did his best to [[UnPerson wipe her from the public record]].
* Parodied with Professor Nakayama of the Sir Hammerlock DLC of ''VideoGame/{{Borderlands 2}}''. When he first appears, he assumes that you've come to square off with him and stop his plans. Hammerlock however clarifies that they're simply here for a hunting trip and have no idea who he is. When Nakayama tries to brag about his various exploits, Hammerlock and the Vault Hunters still don't know who he is, which deeply annoys him.
* The ''Franchise/CrashBandicoot'' series was prone to introducing FunnyAnimal characters, despite the mythos of the series implying all animals with anthropomorphic abilities were mutated by Neo Cortex or N. Brio. Coco, Crash's sister, is introduced inexplicably in the second game for example, her background never referred to (later games and bios clarify she was another mutant of Cortex, though even then she is not shown or mentioned in the first game, the only point she could have been created).
* ''VideoGame/CrisisCore'' combines this with some serious {{Retcon}}ning. Turns out, Sephiroth wasn't driven mad by finding out he was the product of genetic engineering. He was driven mad by a combination of that and Genesis' [[BreakThemByTalking Breaking Speech]]. Who's Genesis? An ''extremely'' {{Camp}} {{Expy}} of Sephiroth who was apparently one of his best buddies back in the day. [[BrokenBase Let's just say fans are divided on how well this worked]] [[InternetBackdraft and leave it at that]].
* A big part of the lore of the ''VideoGame/DivineDivinity'' series involves the Divine Lucian (the player character of the first game) and his adopted son, Damian. ''VideoGame/DivinityOriginalSinII'', set before ''VideoGame/BeyondDivinity'', introduces a character named "Bishop Alexandar", who is the son of the Divine. Previously made games in the series didn't mention Lucian even ''having'' another child, yet ''Original Sin II'' explains him as having been there all along. Fortunately, Larian avoids some other pitfalls of this trope in that ''Original Sin II'' is actually set ''before'' Beyond Divinity and most importantly ''Divinity II Dragon Knight Saga'', and since by this point Alexandar is ''long'' dead, there'd be no reason to mention him. ''Original Sin'' and ''Dragon Commander'', being set in the distant past, of course wouldn't mention him for the fact this was a thousand years before it all.
** [[spoiler: Magister Dallis as well - if the ending that involves removing source from the world is indeed the canonical one, then she is still alive, yet vanishes offscreen and from the lore.]]
* In ''Franchise/TheElderScrolls'' series, the Dragon Cult was a ReligionOfEvil from the Merethic Era who, along with the dragons they worshiped, was defeated and overthrown during the ancient Dragon War. They are a relatively new addition to the series' lore, only being introduced in ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]''. Possibly justified; since the Dragons primarily operated out of Skyrim and frequently battled the Ancient Nords, it makes sense that the Dragon Cult was most prominent in Skyrim and just hadn't been seen elsewhere in Tamriel.
* Marcus in ''VideoGame/{{Fallout 2}}'' and all of the other named Super Mutants in ''VideoGame/FalloutNewVegas'' were members of the Master's Army at the time of ''VideoGame/{{Fallout 1}}''. ED-E from ''New Vegas'' was also established to be built by a Dr. Whitley, a previously-unmentioned Enclave scientist at Adams Air Force Base from ''VideoGame/{{Fallout 3}}''.
* In ''VideoGame/FateGrandOrder'', Nezha's debut in the main story is given little fanfare as the characters briefly mention that she was summoned by Chaldea sometime before the Salem chapter started, and treat her as if she was always there. She ''had'' made an appearance beforehand but only as an NPC cameo in an event that ran ''two'' years prior to her debut, and even then, it doesn't explain how or when she was summoned.
* Lampshaded in ''VideoGame/FinalFantasyX2'': Buddy was apparently there in ''VideoGame/FinalFantasyX'', but Yuna doesn't remember him. Justified in that in ''X'' the entire Al Bhed race was rescued from Home on the Airship, but Yuna wasn't there for that and only got on the ship herself near the end of the story. A throwaway comment from Rikku implies that she, Buddy, Brother and Gippal were all old friends. When you meet Yaibal of the Youth League, Yuna has the option to say she does remember him despite him only being introduced in ''X-2'' (though he does appear in the "Eternal Calm" prologue to the game).
* The entire Taguel race, or at least their LastOfHisKind, is introduced in ''VideoGame/FireEmblemAwakening'' and are treated as an established part of the lore even though they've never appeared before in any game and nothing in particular is ever really explained about them. There are some minor clues that they may be related in some way to the Laguz of ''VideoGame/FireEmblemTellius'', but this has so little support within the game that it tends to stand more as a fan theory.
* The reanimated body of either Kenneth or Jerme in the BossRush at the end of ''VideoGame/{{Fire Emblem|Elibe}}''; you only killed one of them previously, but they both appear in the final chapter.
* ''VideoGame/FiveNightsAtFreddys''[='=] [[VideoGame/FiveNightsAtFreddys2 first sequel]] introduces us to the closest thing the series has to an antagonist for the first time: [[MonsterClown the Puppet.]] Considering [[spoiler:2 is a [[StealthSequel Stealth Prequel,]]]] you would imagine it doesn't survive the events of the game. [[spoiler:Nope, it's still around and screwing things up by the time the first game rolls around, as shown by the cutscene in-between Night Four and Night Five...]] which means it's been around the whole time, when no mention is made of it ''whatsoever'' in the first game.[[note]]This can be handwaved when you realize the Prize Corner box is probably still around - which means the Puppet could still be around, as well - what with it showing up in one of the drawings in the first game's office, and also there's a room with a deactivated camera for it to hide in. Freddy playing his tune while he's in there becomes [[MusicSoothesTheSavageBeast significantly more helpful in hindsight.]][[/note]]
* ''VideoGame/GodOfWarII'' has Atlas, who recognizes Kratos on sight and clearly bears a grudge against him for some reason, with Kratos recognizing him in term ("Much has changed since we last met!"). The prequel released the following year, ''[[VideoGame/GodOfWarChainsOfOlympus Chains of Olympus]]'', reveals that Kratos, during his time of servitude to the Olympians, was the one who chained up Atlas on top of the Pillar of the World to begin with.
* ''VideoGame/GuildWars'' has an interesting relationship with this trope - particularly in that they Zig-Zag it. While it may seem that Abaddon is a case of this, a veteran from 2005 might remember Abaddon's maw in ''Prophecies''. However, ''Eye of the North'' plays this straight with the Norn and the Asura, who have apparently been in the world just as much as humans, Charr, and Tengu (And have even shared the same landmass!) but are ''just'' being introduced. Apparently, humans have never saw signs of Asura on the surface, and the Ebon Vanguard apparently didn't notice the Norn whose territory they regularly scout. Somewhat justifiable in that news doesn't always travel fast, and the Ebon Vanguard is an independent organization.
** Averted with the Sylvari - ''Guild Wars 2'' states them as being the newest race, and makes zero effort to claim they've always been there. They may seem a bit like an AssPull, but there was a little bit of backstory to the Sylvari in Eye Of The North. [[GuideDangIt Hope you didn't blink - you probably missed it.]] The lead up to Heart of Thorns reveals that the recent origin of the Sylvari wasn't just to justify another race in ''VideoGame/GuildWars2'', but was [[spoiler:a massive, plot-relevant ChekhovsGun]].
* Dr. Arne Magnusson from ''VideoGame/HalfLife2: Episode Two'' is apparently a vital and high-ranking member of LaResistance - and had a similar role back in Black Mesa - who just happened to have never been mentioned at all previously. The explanation given is that he's the guy whose lunch Gordon can blow up before the resonance cascade in the original game.
** ''Half-Life 2'' does this ''a lot'', due to the first ''VideoGame/HalfLife1'' almost entirely making use of generic [=NPCs=], though in some cases (Barney Calhoun and Dr. Isaac Kleiner) the effect is lessened by taking those generic [=NPCs=] from the first game and [[NominalImportance turning them into unique characters]] (also helps that Barney was the protagonist of ''Blue Shift'',[[note]]that expansion established Barney specifically to be the guard in the tram tunnels from the opening, banging on the door trying to get someone to open it[[/note]] and Kleiner was [[AllThereInTheManual mentioned in the game's manual]] as one of Gordon's college professors who ended up helping him get into Black Mesa[[note]]a semi-popular fan theory is that Kleiner was the scientist wielding a shotgun at the entrance to the Lambda Complex in the original game, due to a scene with him that homages this one after you teleport out of Nova Prospekt in the sequel[[/note]]). Eli Vance likewise has a line upon actually meeting him face-to-face in ''2'' indicating he was the black scientist who asked Gordon to get topside and call for help immediately after the resonance cascade. Alyx, Eli's daughter, {{lampshade|Hanging}}s this in her introduction, stating that Gordon probably doesn't remember her - on top of having a valid reason for why she didn't show up in the first game (that being [[HideYourChildren she'd have only maybe been one year old]] during the incident at Black Mesa). Judith Mossman is likewise introduced as a former UnknownRival to Gordon back in the day, thus the player is unaware of anything she may have done before the second game because Gordon isn't either. The only particular standout case of this trope, other than the aforementioned Magnusson, is Dr. Breen, [[OneDegreeOfSeparation former administrator of Black Mesa]] at the time of the resonance cascade turned [[BigBad administrator of the Combine's presence on the planet]].
* ''Franchise/{{Halo}}'':
** In ''VideoGame/{{Halo 2}}'' the Prophets were treated this way for people who didn't read the books, where they had already shown up several times. This is justified by you not getting a good look at the inner workings of the Covenant in the [[VideoGame/HaloCombatEvolved first game]] (though its [[Literature/HaloTheFlood novelization]], released between ''Halo 1'' and ''2'', did show that a Prophet was indeed attached to the fleet hounding you).
** As were the Engineers in 2009's ''VideoGames/HaloWars'' and ''VideoGame/Halo3ODST'' - while they had already shown up in ExpandedUniverse material from [[Literature/HaloTheFallOfReach the very first book onward]], and were even DummiedOut from the first game, those entries were their first actual in-game appearances.
** The Brutes, also introduced in-game in ''Halo 2'' , were this as well, though not entirely intentionally. Initially, the events of ''Literature/HaloFirstStrike'', which took place between ''1'' and ''2'', were meant to be humanity's first encounter with the species. Then every bit of ''Halo'' media taking place before the original game featured them anyways - to the point that ''Literature/HaloContactHarvest'', written by one of Bungie's own main writers, had them as the ''second ever'' Covenant race humans have met and fought with - which resulted in the opposite effect where their ''lack'' of presence in the original game is EarlyInstallmentWeirdness. A 2010 reprint of ''First Strike'' removed all mention of Brutes being newly-introduced.
** The Drones, yet another species introduced in ''2'', were ''also'' this, with the original explanation being that the Covenant didn't start using them in battle until near the end of the Human-Covenant war. Like with the Brutes, this was retconned away as later works showed that they had been fighting humanity for the entire duration of the war.
** Series prequel ''VideoGame/HaloReach'' introduced the Skirmishers, a LightningBruiser subspecies of the Jackals, who were never fought in the previous games. The given explanation by {{Creator/Bungie}} was that they were wiped extinct by the carnage at the Fall of Reach, though this didn't explain why they didn't show up in other media taking place chronologically ''before'' the first game like the aforementioned ''Halo Wars''. And again, this original explanation was retconned away as later works showed that there were still plenty of Skirmishers around long after the Fall of Reach.
* Witch Princess was introduced in ''VideoGame/HarvestMoonDS'' but is the long-standing rival to the Harvest Goddess from ''VideoGame/HarvestMoonFriendsOfMineralTown''.
* The ''Franchise/KingdomHearts'' series has two examples, in a rather convoluted fashion. A bit of background: In [[VideoGame/KingdomHeartsI the original game]], the BigBad is a king named Ansem who Mickey Mouse met in the backstory. In the next game, ''VideoGame/KingdomHeartsChainOfMemories'', the Ansem character reappears and there is also a new character who calls himself [=DiZ=]. It's implied that [=DiZ=] is another incarnation of Ansem, as Mickey finds him familiar. The trope comes into play in ''VideoGame/KingdomHeartsII''. [[spoiler: The heroes run across a painting depicting a guy they haven't seen before. When Mickey sees the painting, he claims this new character is Ansem, and the Ansem from previous games is actually an imposter. This is despite the fact that even Mickey called the imposter "Ansem" in previous games. It's later revealed that [=DiZ=] is this true Ansem, while the imposter was Ansem's never-before-mentioned apprentice Xehanort. Thus both the real Ansem and the Xehanort character fit this trope despite technically being introduced in previous games.]]
* ''Franchise/TheLegendOfZelda'' has Hylia, introduced in ''VideoGame/TheLegendOfZeldaSkywardSword'' as a GodOfGood tasked by the Golden Goddesses with guarding the Triforce, the patron deity of the tribe of humans who would subsequently become known as Hylians, the namesake of the land of Hyrule, and [[spoiler:the ancestor of the Royal Family specifically and the Hylians in general on account of the first Zelda being her reincarnation]]. Despite filling such a crucial role for the people of Hyrule, none of the previous ''Zelda'' games from any of the different timelines made any mention of her. Gets even weirder with ''VideoGame/TheLegendOfZeldaBreathOfTheWild'', the first major console game to be released after ''Skyward Sword'', which is stated to be the latest chronologically in its timeline; statues of Hylia are ubiquitous, and she is worshiped across the land as Hyrule's patron deity. Before ''Breath of the Wild'', fans assumed that the people of Hyrule had forgotten about the Goddess Hylia after so long to justify her absence in previously made but chronologically subsequent games.
* ''VideoGame/MapleStory'' does this a lot. Examples:
** In ''Black Heaven'', you are often accompanied by three bird-like {{Non Player Character}}s named Dolpi, Gupi, and Lepi. The dialogue suggests you've known them for a long time, although this is the first time they appear.
** In the Madhouse scenario, released in the 2015 Halloween event, your goal is to rescue an old friend named Chloe from a Bedlam House, and some other friend - Eddie, Marilyn, Chu, Lopez, and Sean - come with you. Thing is, all six [=NPCs=] don't appear in any previous scenario, despite dialogue that suggests you've known them for a long time.
* ''VideoGame/MegaMan7'' introduces Auto, an {{otaku}} GadgeteerGenius who has apparently been working for Dr. Light long before the start of the game.
** ''VideoGame/MegaMan2ThePowerFighters'' introduces Duo, who Mega Man and co are already familiar with despite this being his first appearance. In Duo's ending, it's revealed that this is because [[spoiler: the game is a StealthSequel to the then-unreleased ''VideoGame/MegaMan8'', which is Duo's first chronological appearance, and his inclusion was to promote the game.]]
** ''VideoGame/MegaManX3'' has Mac, a Maverick Hunter who X trusts enough to fall for a trap sprung by him when he turns out to be TheMole in the first stage.
* Anthony Higgs from ''VideoGame/MetroidOtherM''. "[[MemeticMutation Remembah me?]]" He later goes on to make absolutely sure that you do.
** In a sense, Adam is this in ''VideoGame/MetroidFusion'', although it's less noticeable here given he's a PosthumousCharacter who we never heard mention of before simply because Samus never really mentioned much of ''anything'' about her life before the bounty-hunting gig until that game. [[spoiler:The reveal that the computer she's nicknamed after Adam [[BrainUploading really being Adam]] also works because Samus herself ''didn't know'' the Federation did that sort of thing.]]
* DLC character Skarlet from ''VideoGame/{{Mortal Kombat|9}}'', who is present during the ''[=MK1=]''-era events according to the story mode, but never interacts with any of the characters. This is probably intentional, as she's an [[AscendedMeme Asce]][[AscendedGlitch nded]] UrbanLegendOfZelda.
* ''Franchise/{{Pokemon}}'':
** ''Pokémon'' is probably the most extreme example, considering that every legendary is from a legend from long ago, but was only recently introduced to the games' audience. Plus the other 651 (and counting) or so Pokémon introduced after Gen I. This is particularly weird because it sometimes tends to handwave it as the newly introduced Pokemon being newly-discovered species... even though the residents of that region all know more than enough information about these new mons to train and use them for the same purposes as any other region, which sort of implies that the regions don't interact with each other a whole lot. It's especially odd with the almost-obligatory [[VideoGameRemake remakes]] two or three generations later, where once the player beats the Elite Four, the next 200 or so extra Pokémon introduced since the original version will [[UnusuallyUninterestingSight just sort of appear out of nowhere without garnering any attention from anyone]] beyond the local Professor first telling the player that they're here now.
** In the [[NoExportForYou Japan only]] sequel to ''VideoGame/PokemonTradingCardGame'' there is an option to play as a female character. The story still treats them as having done the events in the first game, despite not existing in the first game.
* Krauser from ''VideoGame/ResidentEvil4''. He's a guy that protagonist Leon met in the time period between ''VideoGame/ResidentEvil2'' and ''4'', though what's a tad jarring is that the game seems to take this trope a step further, introducing him almost as if his presence was some kind of shocking plot twist (which is further reinforced by the fact that, from Leon's in-universe perspective, it ''is'' a shocking twist) and acting as though a first-time player is somehow supposed to know who he is. His introductory cutscene even makes it a point to dramatically reveal his face in a close-up.
** ''VideoGame/ResidentEvilTheDarksideChronicles'' retroactively addresses this with its storyline, with Leon and Krauser as the two protagonists of the main plot (which is set a few years before ''[=RE4=]''), and the trope becomes effectively averted if you actually play the games in chronological order.
** ''VideoGame/ResidentEvilRevelations'' pulls the same thing with Raymond, who shows up out of nowhere, is given a dramatic reveal of his face in a close-up, and then pulls his gun on Jill and Parker before the screen fades to black and leaves a first-time player wondering why the devs thought this would work now when it didn't work for Krauser. Fortunately, unlike Krauser the game does address this immediately, as the next chapter opens with a flashback to the "Terragrigia Panic" an in-universe year prior, where Raymond actually does get a minor speaking role and even a namedrop (though you have to stick around for a few minutes at the beginning to hear it from someone else, since Parker seems [[InsistentTerminology oddly hesitant]] to refer to him by [[OnlyKnownByTheirNickname any name other than "Cadet"]]) before the game gets back to the present day.
** ''Videogame/ResidentEvil7Biohazard'' has Joe Baker of the ''End of Zoe'' DLC. He's a member of the Baker family that has gone completely unmentioned until the DLC and has managed to avoid getting infected like the other members since he lives in the outskirts of the Baker property.
* ''VideoGame/SaintsRow2'' does this if you create your character as a female, since you could only play as a male in the original. {{Lampshade|Hanging}}d all throughout, alongside said character being SuddenlyVoiced, where [=NPCs=] continually ask if they did something with their hair.
** At the start of the fourth game the player character has become President and has chosen actor Creator/KeithDavid ([[AsHimself playing himself]]) as Vice President. Keith David did voices for previous games, but was almost entirely restricted to the first game (which [[SequelDisplacement few people played compared to the later games]] due to it being a console exclusive), and had never appeared in universe before. Plus, unlike Creator/BurtReynolds in [=SR3=], he wasn't necessarily an instantly recognizable personality, leaving many fans confused about who he was and why he was so important.
** Players may also feel the same way about Benjamin King in the fourth game, who again is an important character despite not having featured since the first game.
* In ''VisualNovel/SharinNoKuni'' Chapter 5, the first-person narrator reveals that [[spoiler:the person he's been narrating to is not the reader, but his sister, Ririko, who actually ''was'' behind him all along]].
* ''Franchise/SonicTheHedgehog'':
** Dr. Eggman was given two robot minions; Orbot, introduced in ''VideoGame/SonicUnleashed'', and Cubot, introduced in ''VideoGame/SonicColors''. Despite having never been seen before, they speak as if they've been around to witness Eggman's failures since the beginning.
** In ''VideoGame/SonicAdventure2'', it's implied that Knuckles has had to deal with Rouge a few times before this particular time when the Master Emerald was stolen. This turns out to be true in ''Anime/SonicX'', as she was seen well before the adaption of that game.
* ''Franchise/SpyroTheDragon'':
** ''VideoGame/SpyroEnterTheDragonfly'' introduces "Dragon Spirit", a large statue that has the spirit of an ancient dragon in it. It never appeared in [[VideoGame/SpyroTheDragon the previous title]], nor does it appear in any other, but it is treated as it was always there.
** ''VideoGame/SpyroAHerosTail'' introduces us to Flame and Ember, two dragons around Spyro's age. In previous games no adolescent dragons were depicted, only hatchlings and adults. The game also introduces a new batch of eggs despite the fact dragon eggs only occur every twelve years.
* Blizzard again. Tychus Findlay was never even mentioned in the original ''VideoGame/StarCraft'', but in the sequel he's been Raynor's old partner in crime, and probably his best terran friend. Though, being Blizzard, they made sure to carefully insert him in continuity through an ExpandedUniverse novel that takes place before the original game and came out shortly before the sequel. As a bonus, that novel also invented an outlaw past for Raynor, before his Confederate marshal days.
** Tychus ''was'' in prison for years before the start of ''Starcraft''; he'd never even seen a Zerg before ''Wings Of Liberty''. Raynor's backstory itself is another story; there was never a hint that the lawman had once been a criminal.
** Also [[MissionControl Matt Horner]], who supposedly was ({{ret|con}}roactively) with Raynor since shortly before Tarsonis, but was never mentioned in [=SC1=]. Why they invented a new character from scratch instead of establishing him to be the same as [[NonEntityGeneral the Magistrate]] is anyone's guess.
** Crown Prince Valerian Mengsk could also be this, as there is not the least bit on a hint in [=SC1=] that Mengsk had ever had a son. The writer of ''Firstborn'', where he's introduced, is at least kind enough to mention that Mengsk was afraid of his enemies using his family against him and hid the truth from pretty much everyone.
* ''VideoGame/StarFoxCommand'' introduces Lucy, Peppy's daughter. She is not mentioned in any of the previous games. You would think Peppy would have mentioned her at least once.
* ''Franchise/SuperMarioBros'':
** Toadsworth, who was first introduced in ''VideoGame/SuperMarioSunshine''. He had apparently been serving the Mushroom Kingdom's royal family for years (which would imply that he had done so even during the events of the original ''VideoGame/SuperMarioBros''). The introduction of the younger version of Toadsworth in ''VideoGame/MarioAndLuigiPartnersInTime'' seems to confirm this.
** Averted with [[OverlordJr Bowser Jr.]], who was introduced in the same game as Toadsworth, yet Mario and Peach clearly haven't seen him before. Peach even remarks, "So you're Bowser's son?" while he was explaining what he had been trying to do to Mario the whole game.
** Speaking of which, although Bowser and Peach weren't really new to the series, games like ''Super Mario World 2: VideoGame/YoshisIsland'' and ''VideoGame/MarioAndLuigiPartnersInTime'' suggest that Mario knew them since his childhood, and that he lived in the Mushroom Kingdom since birth, although previous games as well as the comics and TV shows suggest that he lived on Earth (Brooklyn, New York, to be specific) his whole life.
** Waluigi debuted in this manner on the Nintendo 64's ''VideoGame/MarioTennis'', getting into a confrontation with Luigi immediately after appearing during the game's introductory scene. The reaction Luigi gives implies that the two knew eachother beforehand, and have a long-standing mutual dislike for eachother.
* {{Lampshade|Hanging}}d in ''VideoGame/SuperRobotWarsAlpha 3'' as the Alpha Numbers, especially the colony-living heroes from other ''Franchise/{{Gundam}}'' series are utterly dumbstruck at the discovery of [[Anime/MobileSuitGundamSEED Coordinators]] and the [=PLANTs=] they live in, especially when they find out they've been there the entire time. It's mentioned that Blue Cosmos had been suppressing information on them for the longest time. They really are bastards...
* ''VideoGame/{{Tomba}} 2: The Evil Swine Return'' begins with the titular wild boy going to the rescue of his girlfriend Tabby with the help of his best friend Zippo. Both were nowhere to be seen in the first game.
* ''VideoGame/TombRaiderChronicles'' introduces Charles Kane and Father Dustan, who reminisce with Winston (Lara's butler) of her past adventures. Despite Dustan and Kane being Lara's friends for years, it's the first time in the series that they're actually seen or even mentioned. Originally, Kane was supposed to have been Jean-Yves from the previous game, but due to his real life {{Expy}} not being happy about his likeness being used without his permission, the character was cut and replaced with Kane.
* ''VideoGame/{{Touhou}}'' has done this multiple times, with both [[PuppetMaster Alice Margatroid]] and [[Manga/TouhouIbarakasenWildAndHornedHermit Kasen Ibaraki]] claiming to know Reimu and Marisa in their first appearances, while Reimu and Marisa can't say the same. The general implication is that Reimu is (by her own admission) bad with remembering faces and neither she nor Marisa can be bothered to remember every single person they've met (though Marisa thinks Kasen seems familiar but can't remember her name). Alice's case may be a MythologyGag as, along with Reimu and Marisa, she was one of four characters from the franchise's now non-canon PC-98 era to be rebooted into the current Windows-era canon.
** ''Wild and Horned Hermit'' presents a justified example with Aunn Komano, who acts friendly towards Reimu, Marisa, and Kasen, and says she knows all about them, but none of them recognize her. It turns out that she really ''was'' there from the beginning -- she was one of the Hakurei Shrine's [[https://en.wikipedia.org/wiki/Komainu Komainu]] statues who was turned into a {{Yokai}} by Matara Okina, the FinalBoss of ''Hidden Star in Four Seasons''.
* ''VideoGame/Uncharted4AThiefsEnd'' introduces the audience to Samuel Drake, an older brother of series protagonist Nathan Drake who never once got any mention, despite the fact a lot of who Nate is can be owed to his older brother's influence (both as a person and in his career). [[spoiler:This gets justified later in because Nate considered his brother's supposed death [[MyGreatestFailure a stain on his past]] and never talked about him since]].
* ''VideoGame/{{Warcraft}}'':
** There was never a hint that Grom Hellscream had a son, until suddenly in ''[[VideoGame/WorldOfWarcraft The Burning Crusade]]'', there he was. Particularly significant considering he's eventually elevated to ''the leader of the entire Horde''.
** When you speak to the time-traveling dragon Chromie in Dragonblight, she starts by saying it's good to see you again before asking if it's the first time you've met. This is used to cover up her appearance in an earlier questline in the Eastern Plaguelands that the player may or may not have completed, and references her time travel by saying "You could say that we have met before. To that end, we shall also meet again."
** Lieutenant Thorn is introduced in ''[[VideoGame/WorldOfWarcraft Warlords of Draenor]]'' as a respected Alliance soldier and your new second-in-command. You never having heard of her before is given the excuse that she's not accustomed to needing help like everyone else is (a meta joke about your primary exposure to [=NPCs=] being with quest givers).
** In general, [=WoW=] expansions often toss new characters straight into the plot without any setup, with established characters somehow already knowing them. Just looking at the ''Warlords'' intro experience: Khadgar, Thrall, Maraad, Liadrin, and... Cordana Felsong? Who? Apparently she was a trusted ally of Khadgar and he had known her for a while before stepping through the Dark Portal to alt-Draenor, but we never learn how.
** ''Cataclysm'' retconned worgen and goblin death knights to have been there all along, alongside all the other playable death knights when they broke free of the Lich King's control at the Battle of Light's Hope Chapel. They have different backstories to the other playable worgen and goblins introduced in the same expansion, and have supposedly been around since the beginning of ''Wrath''. Why we haven't seen a single one of them in Northrend is anyone's guess...
* Sergius from ''VideoGame/{{Xenosaga}} Episode 2''. Despite Margulis being very loyal to him, he is not at all mentioned in the first episode.
* Poked fun at with El Trio De Los Muerte, a new member of the QuirkyMinibossSquad in ''VideoGame/{{Guacamelee}}: [[UpdatedRerelease Super Turbo Championship Edition]]''. Their introduction is done in the last few seconds of the scene the villains are introduced in and Juan is killed, where they suddenly walk into the scene and ask "Hey guys, what'd I miss?"

[[folder:Web Comics]]
* ''Webcomic/{{Asperchu}}'' parodies this with the introduction of Groovan.
* In ''Webcomic/ElGoonishShive'', Carol was previously known only as a reporter, but she was revealed in the New and Old Flames storyline to be Sarah's sister, which was understandably already known by all of the main characters, but the reveal itself was [[AssPull sloppily]] {{lampshade|Hanging}}d.
* Most secondary characters in ''Webcomic/{{Frivolesque}}'' are introduced in this fashion, most notably Delphine, Marie-Neige roommate, who is mentioned for the first time in chapter 4 but has been supposedly living with her for years.
* The first chapter of ''Webcomic/{{Gaia}}'' spends most of its time setting up the five main student character, Ilias, Lilith, Alissa, Ryn, and Sandril, before [[spoiler:the Red Hall attack]] kicks off the main plot. At the start of the second, Ilias gets a missive from the other four, and asks his mother about a "Zoltan," who decided to move, and "Aaret," [[spoiler:killed in the attack]]. There was no mention of either in the first chapter, in which the main five seem a fairly tight-knit clique, nor are there any obvious candidates among the miscellaneous students.
* ''WebComic/GorgeousPrincessCreamyBeamy'' was well into its second story arc when the character of [[{{Yandere}} Cheesecake Saint Cherrywell]] was introduced. Played for laugh, since she explained [[http://creamybeamy.comicgenesis.com/d/20060807.html being disguised as someone else and having the flu during her earlier appearances]], which is why we've never seen her at all before.
* A particularly poignant example can be found in ''Webcomic/LeastICouldDo'', when a guy named Noel knocks on Rayne's door. Noel, as the audience is told, is actually Rayne's best bud and wingman from years back, despite never being mentioned prior in the comic's run. Rayne initially acts grumpy about the sudden reappearance, but it doesn't take long at all for Noel to replace John as the number-two character in the strip.
* Parodied in ''Webcomic/PennyArcade'' with Jim, who was apparently part of a PowerTrio with Gabe and Tycho (complete with being The Kirk to Gabe and Tycho's [[TheMccoy McCoy]] and [[TheSpock Spock]]). Unfortunately they never really mentioned him before (or since!) and by the point he's first mentioned, he'd [[DeadAllAlong been dead for six years]].
** He [[ZombieApocalypse tried to get revenge]] for being forgotten in his next appearance... five years later.
* Dale in ''Webcomic/QuestionableContent'' was established as a regular at Coffee of Doom in his first appearance. This one feels much more natural than other examples of the trope can be, though, as the fact that actual ''customers'' are rarely shown in scenes set at Coffee of Doom despite the business being fairly successful had previously been {{lampshade|Hanging}}d and most of his subsequent appearances involve interactions with a character who explicitly ''didn't'' know the main cast beforehand.
* {{Justified|Trope}} in ''Webcomic/SchlockMercenary''. The Toughs are a mercenary company anywhere between several dozen and a few hundred strong, [[RedShirt not all of them identified]]. Introducing a new character [[http://www.schlockmercenary.com/2006-03-02 can and has been as simple as giving one of them a name and a job that lets the audience know what he does.]]

[[folder:Web Original]]
* WebVideo/JonTron has Rockington (a large rock with a face drawn on it), who appears briefly in the intro to one episode, with Jon talking to him like they're well acquainted. The next time he's mentioned, [[PutOnABus Jon somehow managed to lose him.]]
* Princess Amira was introduced in the ''Website/{{Neopets}}'' [[http://www.neopets.com/desert/ldp/index.phtml Lost Desert Plot]] as being the eldest daughter of the late King Coltzan III, who inherited the throne of Sakhmet after his murder. But previously, Princess Vyssa was his only child and according to her [[http://www.neopets.com/neopedia.phtml?neopedia_id=32 Neopedia article]] (written prior to the Lost Desert Plot), she was his heir. Amira's sudden appearance was explained by her having been away on official business before.
* The writer of the ''Franchise/{{Noob}}'' is trying to have the different media both complementary and potentially independent from each other. One of the consequences is that a medium sometimes has a character formally introduced in another just appear with everyone already knowing them.
* Parodied in ''WebVideo/UltraFastPony''. After the girls get invited to Twilight's brother's wedding, Applejack actually interrupts the theme song to complain about how he's never been mentioned before.
-->'''Rarity:''' Twilight, you can't just randomly decide that you've ''always'' had a brother!\\
'''Twilight:''' What?! I ''have'' always had a brother, I just haven't talked about him until now.
* ''WebVideo/SailorMoonAbridged'' lampshades this with Serena's friend Molly's friend Katie, the VictimOfTheWeek when Nephlite is first introduced.
-->'''Molly:''' I'm really worried about Katie. She's just not the same person as before. [[LampshadeHanging Even though she's never been mentioned before, and will never be mentioned again,]] she's really important to me now.
* vanilla.ice forgot to formally introduce Robert Edward O. Speedwagon during the Phantom Blood spoofs in ''WebVideo/VaguelyRecallingJoJo''. In-universe, Dio, Jonathan and George question Speedwagon after he shows up.
* InUniverse, Paul Pasadena's appearance is this to ''WebVideo/AgainAFanficCritic'' and [=RegretfullyYours=] when he suddenly appears out of nowhere in the middle of ''Fanfic/BennyLeoJohnnyAndRaeMeetTheSlenderMan''.
* Invoked and parodied in "WebVideo/FilmRiot" when its revealed that stark has been hiding in the attic for the years he was absent. we are then treated to a series of shots from past episodes with him greenscreened in.
* Parodied in ''WebVideo/HalfInTheBag'''s episode reviewing ''Film/{{Sinister}}'' and ''Film/ParanormalActivity4'', where Mr. Plinkett claims he's always had [[spoiler: the ghost of a murder victim]] living with him. When Mike and Jay express confusion, scenes from past reviews are played with the character spliced in, never interacting with anyone else.
-->'''Mike:''' Wow. I need to stop drinking.\\
'''Jay:''' And I need to stop snorting [[https://en.wikipedia.org/wiki/Comet_(cleanser) Comet]].
* ''WebAnimation/{{RWBY}}'': For Volume's two to three, it was assumed that Weiss only had an older sister, Winter. The fourth volume introduces their younger brother Whitley without much explanation. The in-series reason for him never even being implied is likely due to him and his older sisters having a tense relationship.
* Parodied by ''WebAnimation/HomestarRunner'' in their 2015 fan Halloween costumes round-up, with Strong Bad "recognizing" a humidifier in the background as "a dead-on Humidibot costume", and we're treated to a brief scene with Strong Bad interacting with a talking humidifier named Humidibot.
-->'''Humidibot:''' Hey, Strong Bad! I'm Humidibot!\\
'''Strong Bad:''' Yeah, I'm aware of that, Humidibot.

[[folder:Western Animation]]
* Parodied in an episode of ''WesternAnimation/AmericanDad'', when Francine meets her apparently best friend at her high school reunion. He never appears beforehand (or afterwards), but Francine apparently mentions him a lot.
-->'''Francine:''' This was my best friend in the entire world, [[{{Expy}} Qua]][[Film/PrettyInPink cky]].\\
'''Stan:''' [[LampshadeHanging Then how come I've never heard you mention him once?]]\\
'''Francine:''' [[BlatantLies I mention him all the time.]] I even did that one-woman show, "Mentioning Quacky".\\
'''Stan:''' Oh yeah. I meant to go to that.
* Lucas Troy from ''WesternAnimation/{{Archer}}'', who qualified to work for ISIS back when everyone was just starting, but opted to work for ODIN instead. Despite being the best fit for Archer's [[WeUsedToBeFriends Friend Turned Rival]], he's never been mentioned before his first appearance.
* ''[[WesternAnimation/AtomicBetty Atomic Betty: Mission Earth]]'' introduced Penelope Lang's brother Chaz and Principal Peterson's daughter Regeena. It's handwaved that Chaz was previously attending boarding school, but no explanation is given for why Regeena wasn't already going to her own father's school.
* ''WesternAnimation/AvengersAssemble'':
** Comicbook/TheVision appears in Season 3 with no explanation or origin, and the Avengers are already all familiar with him. The creators apparently assumed the viewers already knew him from the then-recent ''Film/AvengersAgeOfUltron'' movie, even though the show takes place in a completely separate continuity.
** [[Comicbook/MsMarvel Captain Marvel]] debuts in the very next episode, and like Vision, the Avengers all know who she is (though Comicbook/TheFalcon has never met her in person). She even has a long-spanning rivalry with Captain America and ribs Hawkeye over an incident where she saved his life.
* ''WesternAnimation/TheBatman'' does this to both Commissioner Gordon and Lucius Fox when they make their debuts. [[http://www.toonzone.net/forums/showpost.php?p=1902711&postcount=58 While according to]] [[WordOfGod producer Jeff Matsuda]], Gordon was the young officer in the flashback in "Traction", Gordon hadn't appeared in the present until "Night and the City", where it's revealed that he'd had his alliance with Batman for a while before that episode, despite Ellen Yin filling that role in the show before he appeared. Likewise, Lucius is used in a similar manner to his ''Film/TheDarkKnightTrilogy'' counterpart, though while his debut episode, "The Joining, Part 1" does present him as being present behind the scenes, it did show him meeting Dick Grayson for the first time.
* Max Gibson appears in the second season of ''WesternAnimation/BatmanBeyond'' as one of Terry's closer friends, despite not appearing or being mentioned at all in the first season.
* ''WesternAnimation/BeastWars'' has this with Depth Charge in season 3. He's an old enemy of Rampage and a guy who tried to convince the Maximal Elders to execute Rampage, which Optimus Primal argued against. He's never mentioned before his first episode. The massacre Rampage is supposed to have performed that made Depth Charge so revenge obsessed is not mentioned by Optimus in previous episodes when he mentions Rampage's origin. He's simply called "treacherous and insane". Apparently the fact he murdered ''a colony and a star base'' (and ''ate'' some of them) was not worth mentioning. Neither that a lone survivor from the aforementioned colony tracked him down and captured him. In its defense though, since as far as they knew Depth Charge was a trillion miles away and centuries in the future, there really wasn't a lot of reason to mention him. Optimus definitely didn't seem inclined to do much mentioning of the details of Rampage, and most of the other Maximals didn't know anything about it. Also, since Optimus wasn't on Colony Omicron or Starbase Rugby the story of that may not mean as much to them. The fact that Rampage is violent and insane covers all his men needed to know.
* ''Franchise/{{Ben 10}}'':
** ''WesternAnimation/Ben10AlienForce'' gives us Ken, Gwen's older brother who was never mentioned or even suggested she even had any siblings up to that only episode he has appeared in. After that he is never mentioned again. Suggesting he was created solely to give Max a reason to come out of hiding.
** ''WesternAnimation/Ben10Omniverse'' handwaves most of the "New Guy" moments by Ben imperfectly rebuilding the universe after he kinda blew it up.
*** The series has Ben using the Feedback form in flashbacks to when he was 11 years old, even though it has never been seen in any of the other series. Even bigger, the form is portrayed as his ''favourite alien'', despite all previous shows having Ben's first choice for most situations (at least when the Omnitrix lets him pick) be a [[TheBigGuy huge muscular bruiser]] like Four Arms or Humungousaur. Lampshaded by Gwen, who asks him at one point why he's suddenly always using Feedback. This is somewhat justified by [[spoiler:the fact that losing his alien form to Malware was such a traumatic experience that Ben decided to try and forget about it]].
*** Parodied with Billy Billions. Remember Ben's rival from back in 6th grade? [[UnknownRival Neither does Ben.]]
* The ''WesternAnimation/BikerMiceFromMars'' episode "Diet of Worms" had Lawrence Limburger form a meeting with three other Plutarkian bosses: One-Eyed Jack Monterey, Gerald Gruyere, and Gutama Gouda. The Biker Mice recognize One-Eyed Jack Monterey and Gerald Gruyere even though they didn't appear in any previous episodes.
* Inverted in ''WesternAnimation/CareBearsAndCousins'', probably to set up for the FleetingDemographicRule[[note]]The cousins had not been seen for over two decades, 11-13 years if you count in Play Along Toys' failed attempt to reintroduce them in the early 2000s[[/note]] and or comedic effect. In the first episode, none of the bears except Tenderheart knew who the cousins were.
* The prequel to ''Literature/CliffordTheBigRedDog'', ''Clifford's Puppy Days'' introduces Daisy as Emily Elizabeth's pet rabbit. She is not present or even alluded to in the sequel which causes FridgeHorror of what could have happened to her since.
* Parodied in an episode of ''WesternAnimation/CloneHigh''. Not only is it established (and repeatedly lampshaded) that the hitherto unseen Ponce de Leon is one of the most popular students at the eponymous high school, but he's also best friends forever with main character JFK (who has a BFF tattoo on his left arm--seriously, it borders on sheer HoYay). And, oh yeah, [[TonightSomeoneDies Ponce dies in the same episode]].
-->'''Julius Caesar:''' Oh, Ponce, you're a regular character!
* In ''WesternAnimation/TheClevelandShow'', Cleveland's friend circle abruptly added in a sixth member, this being a generic background guy named Franklin. Their explanation to his presence was that he just started hanging out with the guys a week ago, and Franklin said that he looked forward to many future adventures and wacky hijinks with the old crew for years to come. Immediately after his on-screen debut, Franklin died in a game of Hurt Locker gone wrong, and it was treated as a tragic event by the rest of the cast. His friends, family, and other actual recurring characters were mourning over their tragic loss at his funeral, and of course, he was never seen or mentioned again, seconds after the funeral scene ended.
* In ''WesternAnimation/CodeLyoko'', Yumi's brother Hiroki is first seen in Season 2. He is never mentioned in Season 1, even though the Ishiyama family and home are often involved on-screen.
* In the series finale of ''WesternAnimation/DrawnTogether'' a character is "voted" off the show. After much suspense the character revealed to get the boot was Munchkin Mouse, a character never seen in any episode of the show. All the characters are shocked to see Munchkin Mouse go and a montage of "Munchkin Mouse's Greatest Moments" is played featuring the same image of Munchkin Mouse spliced in to memorable scenes from the show.
** Similarly done in "A Tale of Two Cows." Even though Wooldoor Sockbat only met Live Action Cow at the beginning of the episode, there's a montage at the end of him remembering the good times he had with her, which is really shots from other episodes with Live Action Cow crudely inserted in. There were even scenes that Wooldoor didn't originally appear in, with him and Live Action Cow often replacing characters that were involved with the original scene.
** In the second go-around of 'cast member gets kicked off', it's Excludie, the character everyone excluded from their activities. This even parodied where the others were dying of cold and he was given a warm blanket and something warm to drink so he could not die with them.
* ''Literature/{{Franklin}}'' introduced several characters' younger siblings in this way, most notably Kit, who was introduced as being near preschool age in ''Back to School with Franklin'', even though Beaver had never been referenced as having a sibling before in five seasons of the show. He was never seen again, either.
* ''WesternAnimated/EverAfterHigh'' introduced Crystal Winter, who was talked about as if she was everyone's best friend and favorite person.
* ''WesternAnimation/HiHiPuffyAmiYumi'' has Julie, the former third member of the band, return for a reunion tour in the episode "Julie [=AmiYumi=]". The reason we never saw her before was handwaved by the explanation that Ami hated Julie, who treated her like crap, and didn't really want to talk about her ever again.
* Portia pops up in an episode of ''WesternAnimation/HollyHobbieAndFriends''. The characters reference past things and how [[OOCIsSeriousBusiness she's acting odd]] but it's hard to understand as she's a new character.
* The Phantom Blot only appeared in two Mickey [=MouseWorks=] shorts: "Mickey Foils the Phantom Blot" and "Mickey and the Color Caper", the latter being one of the [=MouseWorks=] shorts that debuted in ''WesternAnimation/HouseOfMouse''. In spite of those shorts being his only two appearances, the Phantom Blot is implied to have menaced Mickey and his friends for quite some time. In "Mickey Foils the Phantom Blot", the Blot tells Mickey that he and his friends have met him again for the last time. "Mickey and the Color Caper", which appeared on ''House of Mouse'' before "Mickey Foils the Phantom Blot", had Mickey rather quickly figure out that the Phantom Blot was to blame for the disappearing colors.
* ''WesternAnimation/InvaderZim'':
** Lampshaded in the Christmas special, where Zim insists Minimoose has been with him the entire time. WordOfGod says that, time permitting, there would've been a little montage of scenes from previous episodes with Minimoose crudely taped onto the picture at that point. The real reason for this discrepancy is that the Christmas special was intended to appear after an episode introducing Minimoose, but when the creators realized the show was soon to be cancelled, they made the more-profitable Christmas special early without regard to continuity.
** Zim tried to invoke an inverted form of this trope when he pretended to know who Dib was after joining his class in the very first episode.
* ''WesternAnimation/IronMan'':
** Titanium Man debuts in the episode "And The Sea Shall Give Up Its Dead," and mere ''seconds'' after the villain appears onscreen for the first time, Iron Man says "Titanium Man? I thought we finished him off at Magnitogorsk!"
** Season 2 introduced a CanonForeigner villain named Dark Aegis. He was established as a dreaded foe who was thought to have died during a past battle with Iron Man, despite never having shown up prior to his one and only appearance.
* After it's first season had middling ratings, ''WesternAnimation/JohnnyBravo'' was {{ReTool}}ed during its second season, which introduced two new regular characters: Carl Chryniszzswics, a HollywoodNerd who insists he's Johnny's best friend, and Pops, mentor to Johnny and owner of a local diner and quite possibly a few other, sketchier business ventures. They are treated as though they always existed despite not appearing nor being mentioned in the first season. After the show returned to it's original style in the fourth season, Carl was DemotedToExtra and Pops only had a brief non-speaking cameo in one episode.
* Of the original seven members of the ''WesternAnimation/JusticeLeague'', Shayera Hol (formerly Hawkgirl) was a blatant example of this. She'd never shown up anywhere onscreen in the Franchise/DCAnimatedUniverse continuity prior to her first appearance in the three-part premiere episode "Secret Origins," but the other main characters evidently already knew who she was. "Starcrossed" mentions that she's been on Earth for 5 years now. Highly doubtful that the first two seasons went on for 5 years in-universe. John Stewart, the Green Lantern, also counts, though his example isn't as obvious because the Green Lantern Corps and their individual members had already been shown in the earlier ''WesternAnimation/SupermanTheAnimatedSeries'' episode "In Brightest Day" (where new recruit Kyle Rayner was the focus character).
* The main character of ''WesternAnimation/TheLionGuard'' is a never-before-seen son of Simba and Nala called Kion. At least [[Disney/TheLionKingIISimbasPride Kiara]] is still around, though she's [[NotAllowedToGrowUp inexplicably still a cub]] despite having been an only child throughout the second film. There are also two new cubs despite the fact Kiara was the only cub in her pride according to ''Simba's Pride'', and Timon and Pumbaa have an adopted nephew named Bunga.
* Warner Bros. kind of likes to pretend these days that Lola Bunny, originally introduced in 1996's ''Film/SpaceJam'', was always a ''WesternAnimation/LooneyTunes'' character. Her [[SpinoffBabies baby incarnation]] even made it into ''WesternAnimation/BabyLooneyTunes''. She also appears in ''WesternAnimation/TheLooneyTunesShow'', though that actually subtly acknowledges how recent she is - she's shown as a new arrival who Bugs meets for the first time ever in an early episode, compared to almost everyone else from the classic crew whom Bugs and Daffy have at least been vaguely aware of from earlier in their lives.
* ''WesternAnimation/TheMagicSchoolBusRidesAgain'' features a different teacher from Ms. Valerie Frizzle--her sister Ms. Fiona Frizzle. In the [[Literature/TheMagicSchoolbus original cartoon]], a large number of Ms. Frizzle's family was either seen or referenced (including her brother John), but she never mentioned having a sister named "Fiona".
* ''WesternAnimation/TheMarvelSuperHeroes'' had a case of this in the ''Captain America'' segment that adapted the debut of Baron Zemo and the Masters of Evil. Because there was no rhyme or reason to which comic stories were adapted to episodes of the cartoon, Iron Man recognizes the members Black Knight and Melter as foes he previously fought even though the former's debut wasn't adapted into an ''Iron Man'' segment until much later in the show's run and the latter made no other appearances.
* According to the creators, ''WesternAnimation/MiloMurphysLaw'' is set in the same universe as ''WesternAnimation/PhineasAndFerb'' and Milo was always around, but he never got involved in Phineas and Ferb's big ideas due to his bad luck.
* Taken to an extreme in the second of the ''WesternAnimation/MyLittlePonyTVSpecials'', where only Megan and Spike were re-used. Slightly justified, as there are ''[[LoadsAndLoadsOfCharacters a lot]]'' of ponies. ''WesternAnimation/MyLittlePonyAndFriends'' also didn't include any ponies from the previous specials.
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' occasionally names ponies that have never appeared before:
** Miss Cheerilee's class frequently has new students suddenly show up and be treated as if they've always been there by the others.[[note]]Since there are only nine seats or so in the room, it's possible that they simply rotate schedules.[[/note]] A prominent example would be Featherweight, who was a blank-flank until his introduction, despite a plot point of an earlier episode being that the Cutie Mark Crusaders were the ''only'' blank-flanks left in their class.
** "A Canterlot Wedding" introduces both Twilight's brother Shining Armor and her former foalsitter Princess Cadance. Twilight claims they were her only real friends before she moved to Ponyville (despite her earlier statements that she didn't have ''any'' friends before then), which makes it odd that we ''never'' hear about them for the first two seasons of the show, the latter especially due to her role as Princess. The rest of the mane cast are extremely confused as well; ''they've'' never heard either one mentioned before either.
** Maud Pie especially stands out in that an earlier event is {{retcon}}ned to include her. When Pinkie's origin story is shown in flashback in season 1's "The Cutie Mark Chronicles", we see her with two sisters, Limestone and Marble. In Season 4's "Pinkie Pride" a picture from the exact same scene appears, showing Maud as a fourth filly with no explanation given as to why we didn't see her in the earlier flashback.
** In ''The Mane Attraction'', we are introduced to Countess Coloratura. According to the characters, she is the "biggest pop star in Equestria", and act with stunned reaction at Applejack when [[PopCulturalOsmosisFailure she asks who she is]]. Considering Countess Coloratura has never been mentioned before in the show despite her supposed "fame", [[LeaningOnTheFourthWall Audiences ended up relating more with Applejack]].
** In [[Recap/MyLittlePonyFriendshipIsMagicS6E12FlutterBrutter Flutter Brutter]], we meet Fluttershy's brother, Zephyr Breeze. Much Like Shining Armor and Maud Pie, he comes right out of the blue with no foreshadowing. Unlike Shining Armor and Maud Pie, the mane six act like they've heard of and even met Zephyr before, with Dash definitely familiar with him. Though given what kind of pony Zephyr is, it is perhaps understandable that they wouldn't ''want'' to talk about him...
* The ''ComicStrip/{{Peanuts}}'' special ''Why, Charlie Brown, Why?'' introduces Linus' friend and classmate [[LittlestCancerPatient Janice]]. Though this is the first (and only) time we see her, it's implied they've been friends for a long time.
* The writers of ''WesternAnimation/PinkyAndTheBrain'' (and [[http://www.youtube.com/watch?v=zZSFvntwgEQ Larry]]) parody this trope when a new character, [[Film/TheThreeStooges Larry]], is given the "Remember The New Guy" treatment by Pinky and the Brain. It starts with the theme song, in which Larry shoehorns himself in at the end of each line, setting the tone for the rest of the episode. The [[ExecutiveMeddling network]], for whatever reason, demanded that a third character be added to the main lineup, so the writers created Larry, a character who added absolutely nothing to the formula and obnoxiously inserts himself into both the gags and even the show's theme song, for a single episode. At the end of the episode, Brain realizes that they don't actually need Larry for their plans, so Larry decides to [[Music/SimonAndGarfunkel start a new career as a folk singer and form a duo with Paul Simon, changing his name to "Art" in the process]]. Larry is then for the end segment immediately replaced with yet another new character in similar vein named [[Creator/MarxBrothers Zeppo]], who obnoxiously inserts himself into the credits song. The episode was created as a protest to adding a third character, and to try and show a third character would destroy the chemistry. The network eventually did get [[WesternAnimation/PinkyElmyraAndTheBrain Elmyra]] as their third character, [[IWarnedYou which pretty much killed the series entirely]].
-->'''[[WordOfGod Gordon Bressack]]''': To set the record straight: Charlie Howell and I wrote this episode as a protest to the network who were talking about adding characters to the show. We wanted to show that adding a character would destroy the chemistry between Pinky and Brain. That's why Larry is always in the way, is an afterthought every time Brain talks, and is absolutely no help in the plan, and Brain is such a genius that even in this alternate reality he knows there shouldn't be a Larry.
* ''WesternAnimation/ThePowerpuffGirls2016'' introduces a new Powerpuff Girl named "Bliss" during the second season. No, she's not a recently created character like Bunny was. She's a LongLostRelative that was created ten years prior to the Powerpuff Girls. According to her backstory, the Professor had a rivalry with another professor who created the perfect little boy. Utonium tried to one-up her by creating the perfect little girl but his original creation involving Chemical W wasn't perfect enough. Bliss would lose control of her powers whenever upset or scared. One day Bliss vanished during one of her episodes and was presumed dead until she reappeared ten years later. This all goes against the [[WesternAnimation/ThePowerpuffGirls original show]] and the established backstory of the girls. The girls are the first known {{Artificial Human}}s and Professor Utonium had no parenting experience prior to their creation.
* ''WesternAnimation/RainbowBrite'' just randomly had Moon Glow and Tickled Pink appear one episode without any explanation. Everyone acts like they've always been around.
* Specky from ''WesternAnimation/ReBoot''. Between the final scene of season two and the beginning of season three (both showing the same characters in the Principal Office control room), he's suddenly in the room with them as the main computer guy, and there seems to be an unspoken implication he was there all along.
* Somewhat parodied in the episode of ''WesternAnimation/TheReplacements'' that introduced Abby's younger sister Tiffany. Abby says something along the lines of: "As you all know, my little sister Tiffany has been to boarding school for the past few years." Only for the Daring family to reply: "We didn't know that."
* Subverted in ''WesternAnimation/RockosModernLife'' during the episode, "The Big Answer". Rocko and Heffer drag Filburt off to a bachelor party the night before his wedding accompanied by a rabbit and a [[CartoonCreature weasel(?)]]. At some point during the party, Filburt whispers to Rocko, "Who are those guys?"
* ''WesternAnimation/SheepInTheBigCity'' poked fun at this. When General Specific's cousin General Lee Outrageous made his first appearance, it started with Private Public telling General Specific about his cousin calling, to which General Specific asked if it was the same cousin with whom he had a rivalry that he never mentioned before.
* ''WesternAnimation/TheSimpsons'':
** PlayedForLaughs in the episode "The Itchy and Scratchy and Poochie Show" where the family discusses the new addition of Poochie the Dog on ''WesternAnimation/TheItchyAndScratchyShow''. During this discussion a teenage roommate of the family named Roy, who never appeared before but wasn't treated as a newcomer, suddenly shows up:
--->'''Lisa:''' Adding a new character is often a desperate attempt to boost low ratings.\\
'''Roy:''' Yo, yo! How's it hanging, everybody?\\
'''Marge:''' Morning, Roy.\\
'''Homer:''' (very blasé) Yeah, hiya Roy.
*** Roy then gets PutOnABus in what sounds like a pitch for a stereotypical sitcom near the end of the very same episode:
---->'''Bart:''' I guess people just weren't ready for Poochie. Maybe in a few years.\\
'''Roy:''' ''(carrying a suitcase and a letter)'' Good news, everybody! I'm moving into my ''own'' apartment with two sexy ladies!\\
'''Marge:''' Oh, then I guess this is good-bye, Roy. Maybe we'll see you in a few years. ''(kisses him goodbye)''
** The season 25 episode "Four Regrettings and a Funeral" featured the funeral of beloved character Chip Davis (in reality the character never existed). Originally the episode ended with a montage of images from classic Simpsons episodes with Chip inserted into them (including Chip as the fifth member of the B-Sharps, Chip in the Plow King commercial with Barney and Linda Ronstadt, and Chip in ''WesternAnimation/TheSimpsonsMovie''[='=]s "bountiful penis" scene sitting next to Ned). It was supposed to run during the end credits but it was removed for the broadcast version and replaced with an "In Loving Memory" card for the recently departed Marcia Wallace. The original credits featuring Chip can still be viewed on Creator/{{Hulu}} and Creator/YouTube.
* Dulcy the Dragon in ''[[WesternAnimation/SonicSatAM Sonic the Hedgehog]]''. She just suddenly appears in the second season premiere as if she was one of the Freedom Fighters the whole time.
* ''WesternAnimation/SouthPark'':
** The episode "Quest for Ratings" features the guys running a news show on the elementary school closed circuit television system and they act as though they've always done this and its never mentioned again.
** In the early seasons, Kenny's family consisted of his parents and an older brother; then, in season 9's "Best Friends Forever," there's suddenly a little girl hanging around them. It's not until five years later, in "The Poor Kid," that she is confirmed to be his younger sister Karen, whom he's [[BigBrotherInstinct very protective of]]. For what it's worth, earlier press releases/scripts mentioned Kenny having a sister, but it's odd that so many episodes with the [=McCormick=] family never showed her before the ninth season.
** Celebrity example: "200" was a ContinuityCavalcade where every celebrity ever wronged by South Park joined forces to sue the town. Among them was Creator/TimBurton, never even mentioned in previous episodes. Tim Burton was written into this episode to be mocked. He has thus become the 200th celebrity to be victimised by the town of South Park.
** Parodied in "Red Man's Greed," when a random kid with "ALEX" written on his shirt appears in multiple scenes, each time giving [[MandatoryLine a generic line that any other character could have said]]. It takes until the very end of the episode for anyone to comment on it:
--->'''Stan:''' Dude, who the hell are you?!\\
'''Alex:''' Alex. Alex Glick. [[ContestWinnerCameo I got to come on and do the guest voice thingy]].\\
'''Kyle:''' What?! Get the hell out of here!\\
'''Alex:''' (''exiting'') [[HiMom Hi Mom! Hi Dad! Hi Jill!]]
** "Sons a Witches" from season 21 is centered on a Halloween tradition of the South Park adult males, drinking and smoking crack while dressed as witches, which in itself has never been mentioned before. One of the participants, Chip Duncan, is a new character who nonetheless is implied to do this every year and to be disliked by the others. He's also an example of WeHardlyKnewYe since he turns into an actual witch and the President destroys him with a KillSat.
* The two-part series finale of ''WesternAnimation/SpiderManTheNewAnimatedSeries'' introduced Kraven the Hunter, who was said to have escaped from a Ukrainian gulag after having been beaten by Spidey in a past encounter.
* In ''WesternAnimation/StarVsTheForcesOfEvil'' episode "Cheer Up Star", Star notices that her enemy [[HarmlessVillain Ludo]] has some new monsters in addition to the recurring Mooks he brings along. Ludo, however, asserts that the new monsters were always there in previous attacks.
* ''WesternAnimation/StevenUniverse'': Bismuth from [[Recap/StevenUniverseS3E20Bismuth the episode of the same name]]. Garnet and Pearl are utterly ecstatic to see her and appear to have been close friends with her. Meanwhile, neither Amethyst (born a few centuries after the show's GreatOffscreenWar) nor Steven know anything about her, as Garnet and Pearl never mentioned her, and Rose Quartz never left anything behind that mentioned past members of the team. When they're alone, Amethyst and Steven even talk about how weird it was that Garnet and Pearl never discussed this with them, with Steven reasoning that they prefer not to talk about the war. [[spoiler:It turns out that Rose Quartz at least [[BrokenAce had]] [[PayEvilUntoEvil a]] [[WellIntentionedExtremist good]] [[IfYouKillHimYouWillBeJustLikeHim reason]] [[HeWhoFightsMonsters never]] [[TheUnfettered to]] [[WoobieDestroyerOfWorlds mention]] [[FallenHero her]]...]]
* ''WesternAnimation/SushiPack'' has a tendency to do this for villains. Oleander, Sir Darkly, and Paradoxtor were all introduced as villains that appeared before (Sir Darkly even had a [[FlashbackCut quick recap flashback]]), despite never having proper introductory episodes.
* ''WesternAnimation/TeenageMutantNinjaTurtles1987''
** The episode "Night of the Rogues" had Antrax and Scumbug. Both of them already had toys, but they had never been mentioned in the show proper before that episode.
** In the episode "White belt, Black Heart" Splinter apparently had a human pupil named Yoku, who we have never seen before, and yet the Turtles all knew him and remember their time with him and how he walked out on Splinter.
* ''WesternAnimated/TeenageMutantNinjaTurtles2012'': In the episode "City At War" we meet Karai's best friend Shinigami, who is also a fighter and has been Karai's close friend since childhood. Never mentioned that Karai even had friends until this.
* ''WesternAnimation/TeamUmizoomi'' :
** Bot immediately recognizes The TroubleMakers in the season four premiere "The Boy with the Dragon Skateboard", despite said premiere being the debut of the latter.
** Likewise, inverted. Any character/villain recently introduced in certain episodes/specials, if Team Umizoomi doesn't introduce themselves beforehand, will address Team Umizoomi by their actual name, even if it's never given it out to said character/villain.
*** One example of this inversion is "Umi Cops!", where the Team is called upon by the Police General as The Umi Cops, despite only becoming cops recently.
* When ''WesternAnimation/ThunderCats1985'' began, there were only three mutants: Ssslythe, Monkian, and Jackalman. However, later episodes randomly added a fourth mutant, Vultureman, who had never even been mentioned before.
* Both ''WesternAnimation/TheTransformers'' and ''Franchise/GIJoe'' had this. They would introduce a new character for the episode, and explanation would ever be given as to why we've never seen this guy before, especially when they are characters who would have saved the day in earlier episodes.
** The cast all but ''doubles'' in ''Transformers'' season two due to never-before-seen characters who are treated as having been there all along. In fact, one story ''depends'' on them having come to Earth at the same time as the others -- everyone is affected by "cybertonium" deficiency due to having been away from Cybertron for so long, which rules out anything like only recently arriving on Earth.
** A bit more believable with ''G.I. Joe'', as it can be -- and has been, in some cases -- handwaved as them being new recruits. Alternatively, that they just weren't on duty during past episodes.
* On ''WesternAnimation/WonderPets'', the OriginsEpisode "How it All Began!" would have us believe that Ollie the bunny was the very first animal that the Wonder Pets helped when they first got together, completely ignoring the fact that Ollie only appeared for the first time later in the show's run.

!! In-canon reality-warping or false memory examples:

[[folder:Anime and Manga]]
* ''Manga/{{Bleach}}'': Tsukishima has this as a power. [[spoiler: He did a Remember The New Guy on near everyone Ichigo knows, as part of a gambit to confuse Ichigo into handing over his life. By adding details, he can do things such as change the environment, learn about others, or make them collapse from the stress of conflicting info.]]
* Rolo Lamperouge from ''Anime/CodeGeass'' manages to insert himself into the main cast between seasons 1 and 2. In fact, he is supposedly the main character Lelouch's little brother (replacing the sister he had previously, Nunnally). He's really [[spoiler:an assassin who has been appointed with the mission of keeping watch over Lelouch, after the Ashford students are given FakeMemories and an amnesiac Lelouch is sent there as well, to keep him out of the way of TheEmperor's plans. [[BodyguardCrush It]] [[{{Yandere}} doesn't]] [[BecomingTheMask work]]]].
* In ''Manga/FairyTail'', when Master Makarov selects the candidates for the S-Class exams, one of them is Mest, a character we have never seen before, yet everybody claims he is a valued Fairy Tail member. [[spoiler:He is a spy who inflicted FakeMemories on everybody. And then, hundreds of chapters later, he is revealed to be a Fairy Tail member from the beginning who even erased his own memories to spy on the Magic Council.]]
* [[spoiler: Yashiro Isana]] in ''Anime/{{K}}'' is an interesting example in that even ''he'' remembers having been there all along. By the time of TheReveal half way through the first season, everyone who was made to Remember The New Guy has forgotten him, which is what leads him to realize his memories had been tampered with. [[spoiler: Everyone in the school not only remembered him, they loved him enough to eagerly share their food with him every day.]]
* In ''Anime/MajokkoMegChan'', Meg is a young witch who has been sent to Earth where is adopted by former witch Mami Kanzaki. In the first episode, Mami bewitches her husband and their two children, Rabi and Apo, into believing that Megu has always been the eldest child of the family.
* ''Anime/PuellaMagiMadokaMagicaTheMovieRebellion'' does this with Bebe [[spoiler:a.k.a. Charlotte/Nagisa]], Mami's pet witch. Mami claims to have adopted her long before meeting Madoka and Sayaka, and that they were inseparable ever since; but Bebe appeared only briefly in the original series, when she [[spoiler:literally ''bit Mami's head off'', and then got blown up by Homura]]. She was never Mami's pet before the movie, but none of the characters can remember her being anything else. [[spoiler:It turns out that Homura has manipulated the memories of most of the cast, including herself, and "Bebe" is only the tip of the iceberg.]]
* ''Anime/SCryEd'' pulls an interesting version of this in regards to Ryuhou in the second half, after he's lost his memories and his former organization tracks him down. While he was implicitly already familiar with Kigetsuki's Alters, a trio of [[RidiculouslyHumanRobots almost-entirely-human beings]] called the Tokonatsu sisters, Unkei forces this trope on him by using ''his'' Alter, Mad Sprict, to implant false memories within Ryuhou and make him believe the Tokonatsu sisters were all his fiancées since childhood - complete with revisiting earlier flashbacks to Ryuhou's childhood when he first met Mimori, but with one of the three Tokonatsu sisters taking Mimori's place in the different flashbacks. Ryuhou is definitely ''not'' pleased when his memories actually return.
* ''Anime/YuGiOhGX'': Season 4, where the characters are shown instantly treating the previously unknown Yusuke Fujiwara like he's one of the TrueCompanions all along -- because he's hypnotized them into thinking so. Too bad his magic doesn't work on Judai. It doesn't work on Fubuki either because Fubuki actually knew Fujiwara beforehand (see above).

[[folder:Comic Books]]
* In ''ComicBook/AdventureTime'', Finn and Jake destroy a magical statue and then discover that they now have an adopted sister, Gata, who is intimately familiar with everyone they know and has apparently lived with them for years. Gata was once actually their sister, but their father magically banished her to another universe and removed all memories of her existence after discovering she was an ApocalypseMaiden that created a portal to a dimension filled with powerful demons when she slept. The statue was the seal to that universe, and destroying it restored her to theirs. [[spoiler: At the end, Gata decides to perform a HeroicSacrifice and re-banish herself and the demons (who are led by her birth mother). Finn and Jake instantly forget about her when she does so. This gets a BelatedHappyEnding at the end of the "Dungeon Master" arc, where the defeat of the villains of that storyline somehow strips her birth mother of her powers and allows Gata to safely exist again.]]
* ''Comicbook/ArchieComicsSonicTheHedgehog'': Following the CosmicRetcon (and real-life lawsuit) induced ContinuityReboot, numerous characters have shown up who have histories with the preexisting characters that are completely new to the audience. Possibly lampshaded in the case of Breezie the Hedgehog, whom Amy points out Sonic and Tails have never mentioned to the rest of the team before.
* This seemed to happen with Moonraker's sudden appearance in ''[[ComicBook/TheAvengers Force Works]]''. Everybody knew him and he even was in an ongoing relationship with ComicBook/SpiderWoman. However, Rachel (Spider-Woman's daughter) notices she had never seen him before. Some issues later, Moonraker reveals he was really implanted into the team's history via time travel to warn them and the Avengers about an upcoming attack by Kang.
* In the ''Transformers'' IDW comics crossover, Infestation, Galvatron has his loyal crew of Cyclonus, Scourge and... Bayonet, a female helicopter transformer we've never seen before and is part of the crew. [[spoiler: She is the BigBad Britt, disguised as a transformer who used her powers to mess with everyone's memories to make them all believe that she was there all along. Kup, who's going crazy by this point, is the first to notice, and when trying to write it off as paranoia fails, she [[ImpaledWithExtremePrejudice impales him]].]]
* In ''ComicBook/XMen: Legacy'', [[http://marvel.wikia.com/wiki/ForgetMeNot_(Earth-616) ForgetMeNot]]'s mutant power made people forget his existence the moment they stop actively thinking about him. He's apparently been an X-Men for six, in-story years.
* In the short-lived ''Comicbook/{{Rogue}}'' solo series, Blindspot was retconned into being a friend of Rogue and a member of the Brotherhood, but since she has the power to manipulate memories, she was able to erase all knowledge of her existence after going into hiding.
* One of the ''Comicbook/FearItself'' tie-ins to ''ComicBook/SecretAvengers'' introduced Leonard Gary, a friend of Beast's with Omega-level RealityWarper abilities. Leonard is shown to be so powerful that he [[CrowningMomentOfAwesome literally brings Washington D.C. to life to repel Red Skull's Neo-Nazi invasion]], and yet we've never heard of him before. It is however justified since Beast implies that Leonard deliberately used his powers to hide himself from people like the Comicbook/XMen.
* DC's Moon Maiden and Triumph, and Marvel's Comicbook/TheSentry. All three are modern characters retconned as heroes from UsefulNotes/{{the Silver Age|OfComicBooks}} who happened to save the world in a way that [[LaserGuidedAmnesia erases everyone's memories of them]]. Leading up to the series that introduced the Sentry, Marvel got comic news sources in on the joke; they ran stories about how he really '''was''' a Silver Age hero who was created back then but never used and promptly forgotten. Nor was this the first time Marvel had tried this tactic. 3D-Man was made in the Seventies but his story had him as active since the Fifties. There was even a ''ComicBook/WhatIf'' story where he was present as a founding member of a 50's version of ComicBook/TheAvengers[[note]]this story would later inspire ''ComicBook/AgentsOfAtlas'', which consisted of the same team minus 3D-Man[[/note]].
* A major plot point in the ''Comicbook/AvengersNoSurrender'' crossover involves the return of Voyager, a former Silver Age Avenger who was supposedly lost in time after a battle with Squadron Sinister. [[spoiler: It's eventually revealed that Voyager is really the Grandmaster's daughter, and that she used her powers to infiltrate the team by worming her way into everyone's memories, thus making them all believe she was a founding Avenger.]]

[[folder:Fan Works]]
* Late in ''Fanfic/PerfectionIsOverrated'', Bachiko is introduced as a supposed childhood friend of [[Anime/MaiHime Mai]], and it's claimed that Mai has also known Bachiko's best friend Meiko when she first arrived at Fuuka, in a manner similar to the MarySue examples listed above. Natsuki is confused when Mai and the others assume she knows the two when she knows she doesn't. [[spoiler:It turns out that Meiko, using her powers, altered everyone's memories so that they would remember herself and Bachiko as their friends, as part of an EvilPlan to manipulate everyone's relationships as they see fit with Bachiko's personality altering abilities, and they posed as Mai's friends in order to monitor their progress. Natsuki happened to be outside of Fuuka's campus at the time, and so was not affected by Meiko's power.]]
* Done InUniverse in ''Literature/TheVampireDiaries'' story "Return to Mystic Falls" by [[spoiler: Elena]] who is really [[spoiler: Katherine]]. She had a witch make people think she had been there all along to fool people, [[EspeciallyZoidberg especially Stefan.]]
* Appears sometimes in MyLittlePonyFriendshipIsMagic fanfiction, including to lampshade or explain instances of it in the show.
** In ''Fanfic/PonyPOVSeries'':
*** It is eventually revealed that [[spoiler:Shining Armor literally didn't exist before he was introduced, and once he appeared, the timeline adjusted itself both past and future to accommodate him. When he finds out, it's a TomatoInTheMirror moment for him]].
*** During the Finale Arc, [[spoiler:Button acts like he's always been Sweetie Belle's coltfriend and the Crusaders' SixthRanger. However, this is because from his perspective, it really ''had'' always been that way]].
*** Also during the Finale Arc, [[spoiler:Maud Pie is really the [[AmnesiacGod amnesiac]] avatar of Entropy, the Goddess of Nothingness and Endings. Upon her arrival, characters briefly question who she is before their memories are rewritten so that they believe she is Pinkie Pie's older sister. As Maud doesn't remember being Entropy and only remembers being Maud, she genuinely believes she is Pinkie Pie's older sister]].
** [https://www.fimfiction.net/story/344092/bbbcf BBBCF] explains why Cadance and Shining Armor suddenly appeared at the end of season 2 [[spoiler: by making Shining Armor a newly spawned changeling drone, with the whole wedding a contrived excuse to distract Chrysalis from Cadance's importance.]]
* In ''Fanfic/HarryPotterAndTheNatural20'', Milo is a {{Munchkin}} with the standard ''TabletopGames/DungeonsAndDragons'' PlayerCharacter ability to add details to his backstory at will. So naturally, he exploits this trope for all its worth.
-->"What did you do?" Relkin asked in a hushed voice.\\
"I remembered each and every one of them as a treasured friend or relative from my backstory," Milo said quietly. "One who would never, ever raise a hand against me or impede the cause of Justice or the furthering of Good. And who gets +2 and a reroll against magical orders against their nature."

* In addition to the straight example above, ''Film/MenInBlack3'' also has it happen InUniverse after Boris alters the timeline [[spoiler:by going back to 1969 to kill K]]. J gets on the elevator to go to work and he is joined by another agent, AA, who addresses J as if J is his partner. Neither J nor the audience has ever met this guy before, much less been partnered up with him. J naturally knows something's wrong.

* In ''Grinny'' by Creator/NicholasFisk, the title character has this as an explicit power: by saying "You remember me", she can make adults (but not children) think they've known her all their lives.
* In the ''Literature/PercyJacksonAndTheOlympians'' series, the [[WeirdnessCensor Mist]] can be manipulated to create FakeMemories of a person. For example, after Mrs. Dodds (Percy's teacher and a servant of Hades) attacks Percy and is killed, a new teacher named Mrs. Kerr mysteriously appears to take her place, and nobody but Percy remembers that Mrs. Kerr hadn't always been their teacher.
** [[spoiler:This is also used in the SequelSeries, ''Literature/TheHeroesOfOlympus'', to get Jason's classmates to think that he had always been in their class. Leo Valdez believes that Jason was his best friend, and Piper [=McLean=] even has memories of dating Jason.]]
* The ''Series/{{Torchwood}}'' novel ''Border Princes'' by Creator/DanAbnett (published between series 1 and 2) has pretty much exactly the same plot as the episode "Adam" (below), except [[spoiler: it's a RealityWarper, rather than a memory-alterer, and he isn't doing it intentionally]].

[[folder:Live-Action TV]]
* In ''Series/{{Angel}}'', [[spoiler:Connor]] inverts the trope by being given fake memories of a normal life, so that no one except Angel and Cordelia remembered his true identity. [[spoiler:The Beast]]'s introduction also has shades of this, because [[SuperpoweredEvilSide Angelus]] remembers him but Angel (and thus the audience) doesn't.
* ''Series/BuffyTheVampireSlayer'':
** One of the most significant examples is the case of Buffy's little sister Dawn, whom everyone treated as always being around despite only debuting in the fifth season. She actually ''didn't'' exist before her first appearance; she's really a cosmic key between dimensions, [[MacGuffinTurnedHuman transformed into a human being]] in order to hide her from a demon goddess. The monks who transformed her also [[CosmicRetcon created memories of her in everyone's minds]] to ensure that she has the Slayer to protect her.
** The trope goes far enough that Dawn is referenced on ''Angel'', the spin-off show she never appeared on, because Angel himself would have met Dawn in the first season of ''Buffy''. She also appears in comics and novels set before the fifth season, on the grounds that the characters would have remembered her being there even though she wasn't there before. When a ''Buffy'' animated series, set during their high school years, was in development, Dawn was planned as a main character.
** Another example is when Jonathan suddenly becomes an expert at everything and a hero to the whole world in the 4th season. Although the character had previously appeared in the show (mostly in minor background shots), his insertion as a main character everyone knows is a dramatic change to the storyline. It turns out he used magic to alter reality to insert himself as the main protagonist of the story.
* ''Series/JaneTheVirgin'' introduces Jane's previously-unmentioned first love Adam in season 4. This is especially odd because prior to this Michael was heavily implied to be Jane's first love.
* ''Series/{{Torchwood}}'' based its episode "Adam" on this. Gwen enters the Hub one-day to find a New Guy working like he's been there all along. She's never seen him bef- Oh, wait, of ''course'' she has. [[spoiler: The New Guy is actually an extra-dimensional entity that implanted himself into everyone's memories because he has to be remembered to exist.]] They even did a SpecialEditionTitle sequence that implanted the mysterious new guy.
* ''Series/StargateSG1'': The episode "The Fifth Man" starts with SG-1 having to leave Jack and new member Lt. Tyler behind as they flee a bunch of Jaffa, when they get to the SGC and say that Tyler was injured Hammond says "who?" Tyler eventually comes clean that he's an alien who secretes a pheromone that makes one perceive them as a familiar (even if fictious) figure they have always known. Since he was running from their mutual enemies they let him go. In later episodes, they use the memory-altering compound to infiltrate enemy organizations.
* ''Series/StarTrekTheNextGeneration'':
** Possibly the first lampshaded use of this was during episode "Conundrum". The entire crew is hit with amnesia and forget their ranks. The executive officer, [=MacDuff=], is someone the audience has never before met. Turns out [[spoiler:he is an alien intruder, trying to trick the ''Enterprise'' into attacking the enemies of his species.]] Interestingly, the direction for the episode doesn't go out of its way to present him as a "new guy"; there's no closeup shot with ominous music or anything when we first see him. If you had never seen TNG before, you might not know there was anything special about him at all. Even regular fans might think he's just some random helmsman or other officer, until the crew manifest is recovered.
** Played with in Tasha Yar during the AlternateTimeline in "Yesterday's Enterprise", where she insists she's always been good friends with Guinan. Guinan, of course, never met Tasha and thanks to her species's RippleEffectProofMemory, instinctively knows this is untrue.
* Quite a clever inverted example appears in ''Series/StarTrekVoyager'' when the EMH finds evidence of crew member Ahni Jetal who he cannot remember ever being on Voyager. It turns out that [[spoiler:his memories of her were deleted when he failed to save her life, an event too traumatic for his programming to take. Considering that she really had never appeared on the show before, a possible reading is that the entire series up until that point reflects the EMH's edited memories, and Jetal could have been around and involved in major plot points]].
* ''Series/TheFlash2014'':
** In season three, various alterations to the timeline result in (among other things) Barry having a new co-worker at Central City forensics. Barry is the only one with RippleEffectProofMemory, so only he finds this odd.
-->'''Barry:''' How have I been working with [[{{Jerkass}} this guy]] for a year?\\
'''Joe:''' You say that all the time.\\
'''Barry:''' I'm sure I do!
** When Professor Stein visits during the "Invasion" crossover, he discovers that, due to advice he gave his past self [[Series/LegendsOfTomorrow on his own show]], he has a fully-grown daughter with an entire life story he doesn't remember.
* Inverted in ''Series/TheXFiles'' episode "The Lost Art of Forehead Sweat", about various false memory syndromes including repressed memories and the Mandela Effect. Reggie, the guy who tells Mulder and Scully about the memory conspiracy, insists he's known them for years, and eventually claims to have founded the X-Files, but nobody apart from him remembers this because he's being erased. [[spoiler: He turns out to probably just be crazy.]]

[[folder:Video Games]]
* Invoked and lampshaded in ''VideoGame/FireEmblemFates''. ''Hidden Truths'' reveals that [[spoiler: Anankos's good side had actually given false backstories to Inigo, Severa, and Owain when he took them to his world]]. Since their backstories involve them having earned enough of a reputation in the world to serve the royal family, it's implied that [[spoiler: Anankos possibly warped peoples' memories around to account for their presence in the world]]. Xander, however, points out in his C support with [[spoiler: Laslow]] that he does find it odd that [[spoiler: he has never even heard of Laslow before he was appointed as his retainer]], but he will not [[PragmaticHero question the results]].
** Niles provides an additional lampshade in his supports with [[spoiler:Selena]], pointing out that they may as well have appeared out of thin air before they started serving the Nohrian royal family.
* In ''VideoGame/KingdomHeartsChainOfMemories'', Sora is subject to Castle Oblivion's memory-altering shenanigans, and as he slowly loses some memories, others that he had forgotten come back to him. Through this, he's reminded of his one-time friend Namine, and as time goes on, he speaks of Namine more and more, even though she did not appear in his hometown in the first ''VideoGame/{{Kingdom Hearts|I}}'' and was never mentioned previously. Eventually, he manages to ''completely forget'' about his actual childhood friend Kairi, whom Namine seems to have supplanted in his memories... and there's actually good excuse for all this! [[spoiler: He didn't really know Namine when he was younger, and the Castle's supposed powers were a ruse; Namine was being coerced by Organization XIII into using her unique ability to tamper with Sora's memories in order to serve their own interests.]] Also {{justified|Trope}} in that Namine [[spoiler: practically ''is'' Kairi]].
* Happens in between [[Videogame/TheElderScrollsIIDaggerfall Daggerfall]] and [[Videogame/TheElderScrollsIIIMorrowind Morrowind]] in the [[Franchise/TheElderScrolls Elder Scrolls]] series. Due to an event called the "Warp in the West", also known as a [[TimeCrash Dragon Break]], many things that hadn't been mentioned in the previous two games suddenly become a thing. Including the MultipleEndings of Daggerfall all becoming canon in some way (Even the ending that was cut from the game).

[[folder:Web Comics]]
* In ''Webcomic/CaseyAndAndy'', the guest strips by Rob Petrone (starting [[http://www.galactanet.com/comic/view.php?strip=492 here]]) feature Rob insidiously inserting himself into the title characters' lives (and the title). [[spoiler: [[http://www.galactanet.com/comic/view.php?strip=501 It doesn't end well for him.]]]]

[[folder:Web Original]]
* ''WebVideo/TheNostalgiaCritic'' parodied this trope in his review of ''Film/TheSmurfs2'', in reaction to the film playing this straight with Hackus and Vecky. Just after the Critic comments on Hackus and Vecky, we cut to an outlandish pink-top-hat-wearing character, called Bill, with whom the Critic keeps interacting throughout the episode as though he was part of the regular cast.
** This review was part of his 'Sequel Month' series. In his conclusion for Sequel Month, the Critic mentioned that, in the end, this sequel month, just like the bad sequels themselves, had brought the viewers nothing new. Cue viewers complaining that it has. The Critic answers: [[CrowningMomentOfFunny "What, Bill? He's always been here!"]]

[[folder:Western Animation]]
* This was going to be one of the main points of the failed ''Series/BuffyTheVampireSlayer'' animated spinoff. The show would retell the Scooby Gang's high-school years, with the addition of Dawn Summers, who was intentionally retconned into the fifth season of the show as a plot point, but had not appeared prior to that. Unfortunately, the show was never made.
* The "Total Rickall" episode of ''WesternAnimation/RickAndMorty'' is an elaborate DeconstructiveParody of the trope, featuring tons of never-before-seen characters whom our protagonists insist have always been on the show, but only because they've been conditioned to think so via telepathy; the new characters are actually a species of shapeshifting parasites who can implant FakeMemories in their hosts, convincing the hosts that the parasites are long-time friends who have always been around. Rick and the gang eventually figure out how to tell a parasite masquerading as a friend from an ''actual'' friend: [[spoiler:the parasites can only create happy, pleasant memories, [[AnAesop whereas real relationships generally contain a mix of both pleasant and unpleasant experiences]]]]. And then ''that'' idea is deconstructed when the gang starts killing everyone in the room that they have no negative memories of [[spoiler:and end up seriously wounding a ''real'' friend (who is a straight example of this trope) by mistake, whom the cast had only one negative memory of [[BaitAndSwitch before it got overridden by one of the parasites]]]].
* In Season 5 of ''WesternAnimation/TheAdventuresOfPussInBoots'', the episode "The Iceman Melteth" suddenly features a new orphan, Li'l Pequena, who appears in five episodes before "Remember Me Not" reveals [[spoiler: she's a fairy who can implant FakeMemories, and an agent (or, as it turns out in the season finale, mind-controlled slave) of the Blind King. Dulcinea grows suspicious when she realises Toby's pictures don't include her, and we see her altering Puss's memories so that she was the first person he met in San Lorenzo, and Dulcinea's so that she'd been popping up all through the series insisting they were best friends. And when that doesn't work, she alters everyone's memories to believe ''Dulcinea'' is a monster from the Netherworld..]].