History SailorEarth / LiveActionTV

* ''Series/CuteyHoneyTheLive'' has three girls based on three suits of cards. You can easily come up with a new one to represent clubs. In fact, the ''two other protagonists'' are a canon example of this: Honey's always had heart designs, but interpreting it as the ''suit'' hearts and coming up with diamond and spade girls with the same power is new.

** There's a general rule of thumb for all Kamen Riders: Unless stated otherwise, the Rider Belts can work for ''anyone''. Almost all the Kamen Rider shows have shown at least two people donning the same belt, with Faiz being the most memorable example, as all three main belts had a go at changing hands every so often.

** ''[[Series/KamenRiderFaiz Faiz]]'': It had five riders taking five Greek Letters, leaving eighteen more. There was also a stageshow which featured Kamen Rider Alpha, Beta, and Gamma, with WhatCouldHaveBeen doing Alpha (again), Pi, and Theta. The one downside is that, for the most part, [[spoiler:the wearer of the Driver has to be an Orphnoch or at least have a lot of DNA. But that's okay, more potential to Sailor Earth it.]] [[spoiler:Even then, Delta was implied to be usable by normal humans.]] The movie also introduces a means of giving normal humans a way of using the Kaixa gear, but at the cost of destroying the gear itself.

** ''Series/KikaiSentaiZenkaiger'', a MilestoneCelebration similar but different to ''Gokaiger'', has a team of heroes derived from previous ''Super Sentai'' whom inspired the creators of their gear in-universe. Zenkaiser, the leading hero, is essentially a modernized version of [[Series/HimitsuSentaiGoranger Akaranger]], the original Red Ranger, but colored white to reflect Goranger's Variblune mecha and with the number 45. He is accompanied by four Kikainoids, mechanical people who can transform into both Rangers and mecha, each are modeled on one of the previous Sentai (''Zyuranger''/''Gaoranger''/''Magiranger''/''Boukenger'') and are numbered as such. Sixth Ranger Twokaizer is based on the Gokaigers, resembling a golden version of Gokai Red. In addition, he is supported by two little brothers who transformed into super-deformed robot mecha, each based on a past Sentai (''Ohranger'' and ''Shinkenger''). Rival characters Stacaesar and Hakaiser, created by a villain who has studied Sentai as well, are based on Battle Japan and Fire-Stealth Captor 7, the latter being the red hero of ''Series/NinjaCaptor'', a contemporary of ''Goranger'' which has been likened to ''Super Sentai'' but is not officially classed as such.

* A common occurrence in the ''Series/{{Supernatural}}'' fandom is to create one or more new hunters, often a set of sisters. In the Supernatural universe, this isn't impossible, since hunters exist across the world. While some people create interesting additions to the universe, most are blatant self-inserts, especially because if these characters are female, the boys seem to fall for them by the end.

** Even before then, the show itself introduced a second "Chosen One" through LoopholeAbuse in the second season (Buffy drowned but was revived by CPR; that brief death activated her successor early), and with Faith off the show's canvas from season 4 to season 7, there's three years of canon where she's easily killed off and replace with an OC as required.

* Any series with a MonsterOfTheWeek formula, like ''Series/{{Smallville}}'', makes it easy to introduce a new superpowered character.
* This is easier in ''Franchise/PowerRangers'' than you might think. Considering nearly every team leaves at least one common ranger colour out and the canon [[TheSixthRanger Sixth Rangers]] are allowed to join up late too, all it takes is to pick a season, pick a colour they didn't use, throw a little ''DeusExMachina'' in here and there and voila! The White Ninja Storm Ranger! The Green Dino Thunder Ranger! The Black Mystic Force Ranger! And that's without getting into seldom-used or even non-canon ranger colours.
** Parodied in ''[[Series/PowerRangersSPD S.P.D.]]'' in which one of the minor characters lied to his parents, claiming he was not just a ranger, not just the ''leader'' of the Power Rangers, but the first ever ''Orange'' Ranger. Ironically, ''Franchise/SuperSentai'' did once have an Orange Ranger: Battle Cossack from ''Series/BattleFeverJ''. A few other Orange Rangers emerged in ''Sentai'' years later.
** Similarly, in a few seasons of ''Super Sentai'' there have been people who tried to join the rangers by making their own original ranger costume, which doesn't actually give them any powers. This has happened in ''Series/GekisouSentaiCarranger'' with White Racer, ''Series/BakuryuuSentaiAbaranger'' with [=AbarePink=] and ''Series/DoubutsuSentaiZyuohger'' with Zyuoh Human. [=AbarePink=] made a return in ''Series/KaizokuSentaiGokaiger'', much to Ahim's embarrassment.
** With the government/military-based teams, it becomes a very simple thing to have a random joe in the organization get promoted and saddled with a blank power template. This is especially the case for ''S.P.D.'', which canonically had several squads of Rangers already. Indeed, it is a popular choice in fanon to give support characters who never transformed in canon the chance to transform themselves. This was teased in an episode of ''Series/MashinSentaiKiramager'', but subverted as the [[AnAesop message]] was that the support did not need to fight to be of value to the team. Nevertheless, there was much demand for ''Zenkaiger's'' Flint Goldtweaker to transform seeing that it was she who created the gear for her brother, the SixthRanger; this wish was ultimately fulfilled post-series.
** There are entire ''teams'' created to fill a Power-Rangers-Equivalent of Sentai teams preceding ''Series/KyoryuSentaiZyuranger''. Or the five normal [[Series/GoseiSentaiDairanger Dairangers]] who never got their suits used. Some even go ahead and make future Ranger teams based on the most recent Sentai that haven't been adapted yet. ''Series/PowerRangersMegaforce'' even indulged in some of this canonically, letting the rangers transform into unadapted Sentai teams, though the show gave little to no explanation for where these powers came from, only that they weren't from Earth.
** Thanks to the number of additional mecha that get piloted remotely, it's easy enough to design new Rangers after them. Canon already has the Titanium Ranger (whose colors don't even match his Max Solarzord, but still counts) and the ''[[Series/PowerRangersJungleFury Jungle Fury]]'' Spirit Rangers. In toy form, we have the hideous repaints of the [[Series/PowerRangersOperationOverdrive Operation Overdrive]] Rangers that come with the bikes, and three original Rangers for the Paleomax Megazord of ''Series/PowerRangersRPM''. Those are just the tip of the iceberg when you consider that ''Series/PowerRangersWildForce'' by itself has up to 94 unassigned Wild Zords, the majority of which were never defined in the show...
** Beyond that, there are collectible trinkets that, whilst not having their own Ranger or mecha on-screen, can be made as such in fanon, such as ''Series/ZyudenSentaiKyoryuger'' (''Dino Charge''), ''Series/ResshaSentaiTokkyuger'' and ''Series/KishiryuSentaiRyusoulger'' (''Series/PowerRangersDinoFury''). In the case of ''Kyoryuger'', the 13 Guardians Zyudenchi were once mecha but only a fraction of them were seen.
** There's also the Rangers or Ranger-like heroes that were in the {{Great Offscreen War}}s and {{Cryptic Background Reference}}s -- previous ''Wild Force, Mystic Force'', and ''Samurai'' teams existed and ''so'' little is known of them. Lotsa fanfic fodder there.
** A semi-canon example exists for ''Series/NinpuuSentaiHurricaneger'' in the form of [=TentoRaiger=], introduced in the second season of ''Series/HikoninSentaiAkibaranger''. However, she was a villain--so naturally, the door is left open for fans to imagine what a version of her on the side of good would be like.
*** [=TentoRaiger=] may have been inspired by a WhatCouldHaveBeen plan for ''Series/NinpuuSentaiHurricaneger'''s addaption, ''Series/PowerRangersNinjaStorm'', which would have added a female dark yellow ranger to the Thunder Rangers so that there would be two female rangers and the two ranger teams would both have three members.
** Aditionally, the monsters in the second season of ''Akibaranger'' are Sailor Earths for the monsters of the various official Sentai series, being designed in their style and following their ThemeNaming. When three new members are added to a group of monsters that were named based on the days of the weak, this has the consequence of changing reality so there are ten days in a week.
** It is also speculated that in the reality where the Akibarangers replaced the Dairangers, since [=KibaRanger=] became their fourth member there would have been a fifth member called [=ARanger=], but no information is given about what [=ARanger=] would have looked like.
** It took time for ''Super Sentai'' to introduce the SuperMode, whilst ''Power Rangers'' added the exclusive Battlizer armor relatively early on, which in turn inspired later Sentai power-ups. Battlizers are traditionally reserved for the Red Rangers, though a handful of other Rangers have received "Megabattle" armors. Super Modes are typically tied to mecha and vehicles, and may even entail combining with them. Over the years the ''Power Rangers'' toyline got in on the action by introducing a number of Battlizers, power-ups, vehicles and weapons, even original Rangers which never appeared on-screen.
** ''Series/KaizokuSentaiGokaiger'' has the heroes transforming into past Rangers and gaining access to their powers. In addition to the idea mentioned above (inventing new colors like Gokai White), one fairly popular fan art came up with the idea of Gokai Killer, an EvilCounterpart who could change into Ranger-like enemies like [[Series/ChoudenshiBioman Bio-Hunter Silva]], [[Series/HyakujuuSentaiGaoranger Duke Org Rouki]], and [[Series/GoGoSentaiBoukenger Yaiba of the Darkness]].
** Keeping with ''Gokaiger'', SixthRanger Gokai Silver can combine Ranger Keys, allowing him to turn the two Sixth Rangers of ''Go-Onger'' into one, the Red and Green Gokaigers into Gokai Christmas, and combine the first fifteen Sixth Rangers into the [[SuperMode Gold Mode]] armor. One wonders what other combinations are possible.
** In the thirtieth anniversary movie of ''Super Sentai'' a special ranger called [=AkaRed=] who is the embodiment of all red rangers appears, and has since reappeared once every five years for anniversary celebrations. This has lead to speculation that there are other rangers like him who each embody a different ranger color and would be his teammates. During one of his later appearances he confirms that other rangers like him do exist but the blue member of his team is called [=AkaBlue=], not [=AoBlue=], though this happened in a non-canon miniseries so this might not be true.
** ''Series/PowerRangersDinoCharge'' is the first season without a yellow ranger, which means there are plenty of fics out there where someone finds the missing yellow energem and fills that gap.
** One of the unadapted sentai teams that showed up in ''Super Megaforce'' were the Super Sonic Rangers, who were based on ''Series/ChikyuuSentaiFiveman''. A Power Rangers comic book reveals the backstory of these team. The team included an original Sixth Ranger, Super Sonic Green, who became a SixthRangerTraitor, and destroyed the team and then became an original {{Psycho Ranger|s}}, Psycho Green.
** ''Series/BattleFeverJ'' had each Ranger be based on a different country. That's 5 down, but there's the potential for hundreds more.
** ''Series/UchuSentaiKyuranger'' has 12 Rangers, each based on one of the [[UsefulNotes/{{Constellations}} 88 Constellations]]. 12 down, 76 to go.
** ''Series/KikaiSentaiZenkaiger'', a MilestoneCelebration similar but different to ''Gokaiger'', has a team of heroes derived from previous ''Super Sentai'' whom inspired the creators of their gear in-universe. Zenkaiser, the leading hero, is essentially a modernized version of [[Series/HimitsuSentaiGoranger Akaranger]], the original Red Ranger, but colored white to reflect Goranger's Variblune mecha and with the number 45. He is accompanied by four Kikainoids, mechanical people who can transform into both Rangers and mecha, each are modeled on one of the previous Sentai (''Zyuranger''/''Gaoranger''/''Magiranger''/''Boukenger'') and are numbered as such. Sixth Ranger Twokaizer is based on the Gokaigers, resembling a golden version of Gokai Red. In addition, he is supported by two little brothers who transformed into super-deformed robot mecha, each based on a past Sentai (''Ohranger'' and ''Shinkenger''). Rival characters Stacaesar and Hakaiser, created by a villain who has studied Sentai as well, are based on Battle Japan and Fire-Stealth Captor 7, the latter being the red hero of ''Series/NinjaCaptor'', a contemporary of ''Goranger'' which has been likened to ''Super Sentai'' but is not officially classed as such.
* There are several teams in ''Series/StargateSG1'' that have been mentioned but never seen, leaving a lot of wiggle-room for fans. This one especially is ''really'' easy, as not only is Stargate Command just a US Government agency instead of some weird group of Destined Ones, "SG-1" itself is just a serial designation. Want a full roster of [=OC=]s? No problem, welcome to SG-7. Making it even easier is the fact that there are at least 9 SG teams in canon from the very first episode, up to at least 25 by the 10th season, with the audience getting to see what SG-1 is doing 99% of the time, with the occasional appearance to SG-2, [[SemperFi SG-3]] or SG-4 members. That's at least 100 potential characters. Add to that the fact that the teams are at least somewhat specialized (to say nothing of the Russian team, with a new one most likely being formed after SG-4 was wiped out), and you've got even more to play with. And that's not even counting the people who are almost certainly going to add SG-0 as a secret black ops unit that's better than SG-1 but who nobody knows about.
** With the upcoming ''Stargate'' [=MMO=], it seems likely that players will get to take their SG-Whatevers into the virtual plane. Watch as clans of avatars take on even the toughest of Goa'uld! Of course, video games are generally all [[TheChosenOne about]] [[TheUnchosenOne that]].
** The Goa'uld themselves. Even with the necessity of excluding the Norse pantheon, there's a vast number of mythological deities who were never used in canon. That's a lot to pick from if a fanfic writer wants an OC villain for their OC characters to confront. And with regard to the Norse pantheon, only a handful of the Asgard actually made appearances in canon.
* The same thing happens with ''Series/{{Torchwood}}'', for which the main characters for series 1-3 worked for "Torchwood 3" -- though canon gives explicit designations for 1, and 2, 4 has vanished and is easily brought back for fanfic purposes, and it's not entirely ridiculous to imagine there's Torchwood 5, 6, e, -90423, or what have you. [[spoiler:By ''Children of Earth'', however, it seems that all Torchwoods had been shut down, leaving only a remnant successor with no permanent base [[Series/TorchwoodMiracleDay two years later]]]]. It used to be that you could at least insist Torchwood was solely based in Britain. Following the introduction of Torchwood India in the audio drama "Golden Age", it's quite reasonable to assume there are branches all over the former British Empire, as Torchwood was founded by UsefulNotes/QueenVictoria. Audio drama "The Dollhouse" extends it even further, as it introduces the first branch based outside the Victorian Empire, Torchwood Los Angeles.
* Common are ''Franchise/StarTrek'' fanfics about Starfleet, since we don't even know how many ships there are. At an absolute minimum there must be hundreds.[[note]]WordOfGod from Ron Moore specifies a 30,000 ship fleet as of ''Series/StarTrekDeepSpaceNine''.[[/note]] There are many ships that the main heroes cross paths with for one episode, and it's easy to crew them with [=OCs=].
** It's also possible to do it with ships, as they have themes. Need a new [=DS9=] runabout? Think of a river! Need a new ship the same class as the local version of the ''Enterprise?'' Think of a modern battleship!
** This is also possible with military and crime stories in a contemporary setting like ''Series/{{JAG}}'', ''Series/{{NCIS}}'' & ''Series/NCISLosAngeles''.
** This is done in the ''Literature/StarTrekNovelVerse'', in which the ''Titan'', Riker's command as of the end of ''Film/StarTrekNemesis'', is a ''Luna''-class starship, and each starship in that class is named after a moon...thus giving endless FanFic opportunities there. Nor does it necessarily have to be a moon from our solar system; for example, the names of two Bajoran moons are known. Likewise the ''Literature/StarTrekDestiny'' series establishes that there are at least seven ''Vesta''-class ships, four of which are named after four of the seven hills of Rome (meaning Palatine, Viminal, and Caelian are still open).

** ''[[Series/KamenRiderAgito Agito]]'' explicitly says that all humans have the potential to become Agito, and even if they don't, there's always a G3 style suit lurking around. In fact, whatever happened to G1 and G2? The S.I.C. toyline actually makes use of this, by having a Lord find and fuse with the G1 suit, which had been in storage in the police department's basement with other prototype weapons.

*** With ''Zi-O'' establishing that the Decade riders now have cards corresponding to every rider up to Zi-O and even implied to do the Reiwa Riders, there's still the open question of what the later riders' Final Form Rides would look like.

** ''[[Series/KamenRiderDrive Drive]]'' has a pretty easy motif: vehicles. The main rider's based off a car, the second rider's based off a bike, and TheRival's based off a vehicle that's been modified. Not to mention that there's a lot of copying going around (the monsters can copy people and research notes have been used to make copies) and thus, you can easily have an EvilKnockoff running around.

** ''[[Series/KamenRiderGeats Geats]]'' also goes for animal motifs, with each Rider having their own animal mask. Other than that, pretty much anything goes as far as their equipment is concerned, since the Raise Buckles are all interchangeable. A fan-made Rider could just be given a new generic weapon, or a more individualized weapon of choice to fit the character's style (which, canonically, every Rider has, even though not all of them survive long enough to obtain said weapons)

* Used to be common to insert a new survivor into ''Series/{{Lost}}''. In fact, the ''show itself'' inserted two entirely new crash survivors into the plot during season 3, linking them to several significant events in their sole flashback. Not so common after season 5, which [[spoiler:killed off every survivor that wasn't a main character, Rose, or Bernard.]]
* ''Series/CuteyHoneyTheLive'' has three girls based on three suits of cards. You can easily come up with a new one to represent clubs. In fact, the ''two other protagonists'' are a canon example of this: Honey's always had heart designs, but interpreting it as the ''suit'' hearts and coming up with diamond and spade girls with the same power is new.
* While this didn't really work during the show's run, the ''Series/BuffyTheVampireSlayer'' finale created hundreds of Slayers around the world. As a bonus, Slayers are always teenage girls (except for those who manage to make it to their twenties), and as MostFanficWritersAreGirls...
** Even before then, the show itself introduced a second "Chosen One" through LoopholeAbuse in the second season (Buffy drowned but was revived by CPR; that brief death activated her successor early), and with Faith basically off the show's canvas from season 4 to season 7, there's three years of canon where she's easily killed off and replace with an OC as required.
** ''Series/{{Angel}}'' firmly established that the Slayer being the sole warrior for humanity was a load of poppycock, with numerous individuals and organisations working against (and for) "vampires, demons and the forces of darkness", creating massive fanfiction potential. While most other demon hunters out there are simply BadassNormal humans, the Slayer isn't the ''only'' one with supernatural powers fighting on humanity's side. There's also good-aligned magic users, and even a handful of demons and half-demons who side with humanity (since not ''all'' demon species are soulless sociopaths like vampires).
* With the introduction of a Magic School in ''Series/{{Charmed|1998}}'' Season 6 this opened up mountains of possibilities for fanfic writers to create teenage witches who fight demons. Using additional Elders, Avatars and other such beings is quite easy too since only a handful of them received names on the show. Also due to the show's FantasyKitchenSink nature, plenty of fanfics introduce foes based on mythological creatures the show didn't use -- a German "Season 9" fanfic used Avalon, the Gorgons and the djinn for example.
** The canonical inclusion of a half dozen Halliwell descendants in the finale (who are basically blank templates) and the existence of time travel in-universe lend themselves to this, though the bulk of this type of fanfic focuses on Chris and Wyatt, the two descendants who canonically ''did'' travel back in time at various points to help the Charmed Ones.
* Happens many ways in ''Series/DoctorWho'' fics:
** Time Lords are established in canon as having multiple lives with individual personalities and appearances. Any Time Lord who has appeared in canon, including major characters like the Doctor, can effortlessly become an original character by regenerating them. Some examples of this:
*** During the Wilderness Years, future Doctors were quite fashionable. Some ''canonical'' examples include the Ninth Doctor played by Creator/RichardEGrant, the Ninth Doctor played by Creator/RowanAtkinson, the Doctor played by Creator/NicholasBriggs, the Doctor from the ''Literature/TimeHunter'' novella series who smokes and wears muttonchops, the Doctor used in some Short Trips stories who has an aging apolitical hippie aesthetic (wearing a camel coat and lots of pachouli), and the Eighth Doctor Virgin tried to create before the TV Movie came along, who would've been "played" by David Troughton. And those are just official and semi-official examples -- the fandom took it in even madder directions.
*** Coming up with original future Doctors, or alternative incarnations, based on actors the writer likes (or [[WhatCouldHaveBeen nearly got the role but never did]]) is a popular pastime. Big Finish's ''AudioPlay/DoctorWhoUnbound'' series was a series of one-shot audio dramas featuring various "national treasure"-type British actors having their turn at playing the Doctor.
*** Before he returned to the show in 2021, Creator/RussellTDavies got in on the future Doctor thing in his [[Literature/DoctorWhoNovelisations novelisation]] of "Rose", introducing two Doctors somewhere after Thirteen -- one a tall, bald black woman wielding a flaming sword, the other an [[AmbiguousGender androgynous]] child in a hi-tech wheelchair with a robot dog.
*** The Thirteenth Doctor's era has her [[spoiler:discover countless forgotten lives dating back to the beginning of Time Lord civilization, if not before, drawing on bits and pieces of things in the classic series. If you want to explore what might be buried in the Doctor's forgotten past, or their connections to Gallifrey's history, have a go at creating one of these incarnations]].
*** In New series fics the introduction of the Chameleon Arch allows for any amount of Time Lord survivors hiding in the local populace. Subsequent events offer up additional opportunities for survivors, like the Doctor booting the High Council off Gallifrey in the Series 9 finale, and the reveal [[spoiler:of at least one Time Lord operating outside the universe in "Flux"]].
*** The Master has even more scope for reinvention than the Doctor, to an almost limitless extent. He is stated to already be on his final incarnation by the time we first meet him as Roger Delgado, meaning ''twelve'' entire selves are unaccounted for on TV -- even if you choose to include the War Chief as one of his previous lives, as [[FanWank many people like to]], even if you include Big Finish's James Dreyfus Master, and even if you take seriously the implications that Missy is the first female incarnation of the Master, there's still a lot of room for invention. Even the Alex Macqueen Master used in the Big Finish audios is from the Master's second cycle of lives -- and we don't know how many lives deep s/he is in his/her second cycle[[note]]at least five (the Macqueen Master, the Jacobi Master, the Simm Master, Missy, and [[spoiler:the Dhawan Master]]), possibly six, if you count the Titan Comics incarnation[[/note]], or even whether it's the same length as the first (Rassilon in "Hell Bent" asks the Doctor how many regenerations they gave him, suggesting they're not bound to the old thirteen-lives limit any more). On top of ''this'', the final Master of the first cycle incorporates all the on-screen Masters seen throughout the Classic series and TV Movie, as that incarnation got around his inability to regenerate by stealing bodies (after being a [[{{Lich}} rotting corpse]] for a while), something he had no real practical limit to doing; the body the Master is in when he is executed by the Daleks at the beginning of the TV Movie was probably intended to be the body he took from Tremas, but, since the scene uses a very obvious FakeShemp instead of the usual Anthony Ainley, it ends up being ambiguous.
*** Romana had two on-screen incarnations. The first of these is heavily implied to be her first, and her second is suggested to be the one she fought the Time War in, heavily limiting her scope for reinvention, but official ExpandedUniverse material nevertheless has used multiple Third Romanas, particularly the one used in the ''Literature/EighthDoctorAdventures'' ([[ComicBookFantasyCasting based on]] Louise Brooks) and the one used in ''AudioPlay/{{Gallifrey}}'' played by Creator/JulietLandau. She's also unaccounted for in the New series as of yet even after the restoration of the Time Lords, except that she is no longer President...
** Since there is a non-canon human version of the Doctor played by Creator/PeterCushing, it's very common for fans to conceptualise a corresponding version of the Master played by Cushing's old Film/HammerHorror collaborator Creator/ChristopherLee. Although there are a few short stories and ''Magazine/DoctorWhoMagazine'' comic strips set in the Cushing-verse, this hasn't shown up in any official material yet...
** Several incarnations of the Doctor have been based on other people, with unexplained {{Criminal Doppelganger}}s and unremarked-upon recurring casting appearing in the Classic series a couple of times, and the New series coming up with clever internal explanations for YouLookFamiliar. This naturally means it's possible to have doubles of any of the existing Doctors show up, with {{Actor Allusion}}s of Doctors who played historical figures in other roles being especially common (particularly Creator/DavidTennant's version of Casanova, who often gets paired up with Rose). The fact that Creator/TomBaker's most famous casting before the Doctor was playing UsefulNotes/RasputinTheMadMonk has come up in a couple of books and audio dramas.
** In Classic series fics the Doctor would run into any amount of former classmates and Time Lord renegades who nicked their own TARDIS and legged it, semi-justified as it often happened in canon with the Rani, the Master, Drax, the Monk, etc.
** In fics for both eras the Doctor would land the TARDIS and pick up a totally-not-a-self-insert-at-all new companion (semi-justified, as the Doctor has almost certainly had more companions than the ones on-screen).
** For the vast majority of episodes, the only regulars are the Doctor and their one-to-three companions, featuring otherwise entirely new casts. Fanfiction can and has easily followed this formula.
** A lot of Time Lord [=OCs=] tend to have [=TARDISes=] that look just like the Doctor's police box shape, despite the reason for that being a broken chameleon circuit, working [=TARDISes=] being able to camouflage into whatever environment they materialize in. Other popular variants are the red London telephone booths or the red police boxes [[http://i244.photobucket.com/albums/gg26/robertpool/polisboxred.jpg like the ones that were in Glasgow.]] Red London buses are also fairly common, with Franchise/IrisWildthyme and the televised story "Planet of the Dead" both featuring Doctor surrogates with space Routemasters.
** The existence of a Black Guardian of Darkness and Chaos and a White Guardian of Light in Time was presented on screen as thoroughly dualist[[note]](see especially [[Recap/DoctorWhoS16E1TheRibosOperation "The Ribos Operation"]], [[Recap/DoctorWhoS16E6TheArmageddonFactor "The Armageddon Factor"]], and [[Recap/DoctorWhoS20E5Enlightenment "Enlightenment"]])[[/note]], but the "Guardian of X" formula nonetheless opened the way for other Guardians manifesting or protecting various facets of reality. Eventually this concept made its way into Extended Universe canon as a "six-fold god" that also included [[Recap/DoctorWhoS3E7TheCelestialToymaker the Celestial Toymaker]] as the Crystal Guardian, plus an Azure Guardian of the Quantum Realm, a Silver Guardian of Space and Matter, etc. Other writers scornful of this development jokingly proposed increasingly ridiculous additional Guardians, including a Jolly Green Guardian of Frozen Food, an Ochre Guardian of Puffins, etc.
* ''Series/{{Glee}}'':
** Many writers have yet to realize that adding a thirteenth member to New Directions throws off number balances, as there is usually an even split between boys and girls ([[SixthRanger Jesse]] didn't help that lesson sink in much either, even taking into account that his stay was temporary). As seasons pass, more members are canonically included.
** Thanks to ''Series/TheGleeProject'', many fanfic writers can cast contenders that didn't win as their [=OCs=], which more often than not are usually just the contestant with a different name (sometimes not even that) and slightly more [[GuyOnGuyIsHot hetero]][[GirlOnGirlIsHot flexible]].
* A common occurrence in the ''Series/{{Supernatural}}'' fandom is to create one or more new hunters, often a set of sisters. In the Supernatural universe, this isn't impossible, since hunters exist across the world. While some people create interesting additions to the universe, most are blatant self-inserts, especially because if these characters are female, the boys seem to fall for them by the end.
* Every now and then, ''Series/CriminalMinds'' will mention other, unseen [[TheProfiler BAU]] teams. One of them actually was showcased in the Season 5 episode "The Fight", which became the team for the short-lived spinoff ''Series/CriminalMindsSuspectBehavior''. Another was the JTF-12 team-featured as the targeted victims of the Ian Doyle arc of Season 6--of terrorist profilers that Emily Prentiss was a part of before joining the BAU. And the number of agents in the BAU isn't hard-coded, meaning creators could create another agent to join the team. Care must be taken to ensure the new agent fits in with the team and everyone has their proper roles story-wise, as the cadre of characters can get confusing for the audience if handled improperly.
* There are said to be 127 Elements in ''Series/SapphireAndSteel'', of whom four appear in the televised canon and two more in audio adventures. This leaves ample opportunity for fan writers; they need only pick the name of an element, gemstone or alloy that hasn't appeared in the show, and endow them with appropriate characteristics and powers.

* Wesen are pretty easy to add to the ''Series/{{Grimm}}'' canon. Pick an animal or a mythical creature, tack on a vaguely-related Germanic name and you're all set. New Grimms are even simpler, since anyone with a recently-deceased relative could discover they are one.
* ''Series/TwentyFour'' fans have it pretty simple: since there are so many CTU agents rotating in and out of the series through the show's run, simply have your CTU OC be on assignment somewhere else, which is why they're just meeting Jack Bauer or one of the others for the first time now. As the show has confirmed that there are other branches of CTU outside Los Angeles and even had Jack working with the New York one in the eighth season, this isn't too much of a stretch.

* Fanfic authors for ''Series/UnnaturalHistory'' enjoy pairing up the already hinted Maggie[=/=]Jasper relationship, and writing in an OC (usually very well-travelled as well) to act as a Love Interest to Henry...when they're not writing Henry[=/=]Jasper.

* Coming up with an OC for ''Series/CaptainScarletAndTheMysterons'' is pretty easy -- just pick a colour to give your captain. And since there are many colours, the possibilities are endless.
* There's enough wiggle room in ''Series/StrangerThings'' for one to create a new character who was experimented on by Hawkins Labs. 8 and 11 appear on the show, with 3 and 6 appearing in a tie-in comic, but that leaves another seven super-powered individuals who could potentially exist and meet the rest of the Party.
* Golden-Road.net, a fansite for ''Series/ThePriceIsRight'', is usually rife with people submitting their own original ideas for pricing games. When GSN's message board was active, they had members creating what they thought were improved versions of existing or once existing shows ("Password Ultra," for example) or TPIR pricing games.
* ''Series/TheLordOfTheRingsTheRingsOfPower'': Galadriel refusing Sauron's offer to be his Queen and rule Middle-earth together left a lot of free room for original characters or self-insertions who accept his offer and try to fix him. Some of the fanfics contain characters that are expies of Galadriel.

*** Double? You don't even have to invent new memories from whole cloth. What if Philip and Shotaro used another Rider's Gaia Memories? Or even Dopant Memories? Nazca and Skull are pretty popular choices for those [[spoiler:and Accel is even teased in the show, having Shroud's intention being to fuse Accel and Double's powers together]]. Canonically speaking, however, the non-existence of alternate Fang combos was explained by the Double novel, where it's mentioned that Shotaro's compatibility with the Joker Memory lets him put a leash on Fang's berserker tendencies; any other combo would result in Double becoming uncontrollable. However, in the ''Fuuto Detectives'' manga, [=FangTrigger=] does get used.

** ''Series/{{Angel}}'' firmly established that the Slayer being the sole warrior for humanity was a load of poppycock, with numerous individuals and organisations working against (and for) "vampires, demons and the forces of darkness", creating massive fanfiction potential. While most other demon hunters out there are simply BadassNormal humans, the Slayer isn't the ''only'' one with supernatural powers fighting on humanity's side. There's also good-aligned magic users, and even a handful demons and half-demons who side with humanity (since not ''all'' demon species are soulless sociopaths like vampires).

*** In New series fics the introduction of the Chameleon Arch allows for any amount of Time Lord survivors hiding in the local populace.

** Since there is a non-canon human version of the Doctor played by Creator/PeterCushing, it's very common for fans to conceptualise a corresponding version of the Master played by Cushing's old Film/HammerHorror collaborator Creator/ChristopherLee. Due to the Cushing Doctor being ExiledFromContinuity (except for the short story "The House on Oldark Moor", which features several Hammer elements, but not this) this hasn't shown up in any official material yet...

* ''Series/TheLordOfTheRingsTheRingsOfPower'': Galadriel refusing Sauron's offer to be his Queen and rule Middle-earth together, left a lot of free room for original characters or self-insertions who accept his offer and try to fix him. Some of the fanfics contain characters that are expies of Galadriel.

* Golden-Road.net, a fansite for ''Series/ThePriceIsRight'', is usually rife with people submitting their own original ideas for pricing games. When GSN's message board was active, they had members creating what they thought were improved versions of existing or once existing shows ("Password Ultra," for example) or TPIR pricing games.

** ''Series/{{Angel}}'' firmly established that the Slayer being the sole warrior for humanity was a load of poppycock, with numerous individuals and organisations working against (and for) "vampires, demons and the forces of darkness", creating massive fanfiction potential.

** ''[[Series/KamenRiderGeats Geats]]'' also goes for animal motifs, with each Rider having their own animal mask. Other than that, pretty much anything goes as far as their equipment is concerned, since the Raise Buckles are all interchangeable. A fan-made Rider could just be given a new generic weapon, or a more individualized weapon of choice to fit the character's style.

** With the government/military-based teams, it becomes a very simple thing to have a random joe in the organization get promoted and saddled with a blank power template. This is especially the case for ''S.P.D.'', which canonically had several squads of Rangers already.

** ''Series/UchuSentaiKyuranger'' has 12 Rangers, each based on one of the [[UsefulNotes/Constellations 88 Constellations]]. 12 down, 76 to go.

** Similarly, in a few seasons of ''Super Sentai'' there have been people who tried to join the rangers by making their own original ranger costume, which doesn't actually give them any powers. This has happened in ''Series/BakuryuuSentaiAbaranger'' with [=AbarePink=] and ''Series/DoubutsuSentaiZyuohger'' with Zyuoh Human. [=AbarePink=] made a return in ''Series/KaizokuSentaiGokaiger'', much to Ahim's embarrassment.

* The most common way to parody ''Series/TheRealHousewives'' is "The Real Housewives of [city where the writer lives that hasn't been given its own series]," where each cast member represents a different local stereotype played UpToEleven. Bonus points if it's a traditionally blue-collar city like UsefulNotes/{{Boston}} or UsefulNotes/{{Pittsburgh}} and the ladies are as trashy as can be.

* Every now and then, ''Series/CriminalMinds'' will mention other, unseen [[TheProfiler BAU]] teams. One of them actually was showcased in the Season 5 episode "The Fight", which became the team for the short-lived spinoff ''Series/CriminalMindsSuspectBehavior''. Another was the JTF-12 team-featured as the targeted victims of the Ian Doyle arc of Season 6--of terrorist profilers that Emily Prentiss was a part of before joining the BAU. And the number of agents in the BAU isn't hard-coded, meaning creators could create another agent to join the team. Care must be taken to ensure the new agent fits in with the team and everyone has their proper roles story-wise, as the [[LoadsAndLoadsOfCharacters cadre of characters]] can get confusing for the audience if handled improperly.

** ''[[Series/KamenRiderFaiz Faiz]]'':
*** It had five riders taking five Greek Letters, leaving eighteen more. There was also a stageshow which featured Kamen Rider Alpha, Beta, and Gamma. The one downside is that, for the most part, [[spoiler:the wearer of the Driver has to be an Orphnoch. But that's okay, more potential to Sailor Earth it.]]
*** [[spoiler: Or, you could just be a human with a lot of Orphnoch DNA. Even then, Delta was implied to be usable by normal humans.]] The movie also introduces a means of giving normal humans a way of using the Kaixa gear, but at the cost of destroying the gear itself.

*** With ''Zi-O'' establishing that the Decade riders now have cards corresponding to every rider up to Zi-O, there's still the open question of what the later riders' Final Form Rides would look like.

** ''[[Series/KamenRiderZeroOne Zero-One]]'' did some self-indulging by establishing that almost every Progrise Key can be used in any of the thirteen {{transformation trinket}}s. Designs have shown what'd happen if Zero-One were to use common Progrise Keys beyond his own set, but some take it beyond by making new Progrise Keys, which is easy to do given that one needs to think of an ability and an animal.

*** Former showrunner Creator/RussellTDavies got in on the future Doctor thing in his [[Literature/DoctorWhoNovelisations novelisation]] of "Rose", introducing two Doctors somewhere after Thirteen -- one a tall, bald black woman wielding a flaming sword, the other an [[AmbiguousGender androgynous]] child in a hi-tech wheelchair with a robot dog.