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Cryptic Background Reference

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"Part of the attraction of The Lord of the Rings is, I think, due to the glimpses of a large history in the background: an attraction like that of viewing far off an unvisited island, or seeing the towers of a distant city gleaming in a sunlit mist. To go there is to destroy the magic, unless new unattainable vistas are again revealed."

One way of building background is to have the characters refer to things without explaining exactly what those things are. The slight confusion caused is balanced by the sense given of a larger world, outside the plot. If a story is extended to a long enough series (especially when there's a high turnover of writers), most of these cryptic references will eventually be explained and/or used as Canon Fodder, but often one or two will still never appear in story. What such references really mean are a favorite subject for fan discussions and a breeding ground for various theories. The rise of the web, and later social media, has somewhat reduced the incidence of such things, as it has become easier to just ask the creators what something means; they'll probably answer it if doing so won't spoil future plot developments. Of course, this hasn't totally eliminated them, as there are some things that the creators just don't care enough about to answer or think is better left to fan interpretation.

Compare to the closely-related Noodle Incident which is specifically for the incident in question being too embarrassing and ridiculous to elaborate. See also Canon Fodder, Narrative Filigree, What Happened to the Mouse? and Mysterious Past. Unknown Character, Great Offscreen War and Cataclysm Backstory are commonly played as sub-tropes of this, as is Famous, Famous, Fictional. See Hufflepuff House for organizations with this treatment more referred to than seen. If the reference in question is actually explained later on, it becomes Foreshadowing, Chekhov's Gun, or Brick Joke. If not, it becomes a Noodle Incident. When played for laughs or for horror, it overlaps with Nothing Is Funnier (and sometimes Funny Background Event) or Nothing Is Scarier. Interestingly, if you start following a long-running series from the middle (rather than from the start), every Continuity Nod in it effectively becomes a Cryptic Background Reference for you, so it's all just a matter of perspective, really.


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    Anime and Manga 
  • Considering Blame is a series that prides itself in its sheer vagueness, it isn't a big surprise that this trope shows up at least once a chapter. Technology and factions are seen, mentioned and interacted with often, but in most cases, never fully explained. This adds to the already frighteningly vast feel of the 'Verse, and leaves plenty of room for Wild Mass Guessing.
  • Cowboy Bebop does this all the time, sometimes without even directly saying anything. It oftentimes does this with the main plot and character traits — e.g. Ein is a "data dog", something apparently important and rare which is only vaguely explained, even in the episode where it's mentioned. This is subtly lampshaded — Jet angrily asks Spike why he's running off to kill a man from his past. Spike pointedly (even cynically) asks him how he lost his arm, causing Jet to clam up. The circumstances behind Spike's pursuit of the man and Jet's lost arm are eventually revealed.
  • Eureka Seven:
    • This anime features the characters spouting a lot of Gratuitous English phrases that won't mean anything until a good twenty episodes later. It gets pretty confusing when half of the spoken terms have no meaning to the viewer.
    • Its sequel, Eureka Seven AO is slightly better. There are a lot of references to events in the past, and several hints that there is something off about the Alternate Universe. They also managed to cut the introduction to meaning rate by about 50%, meaning that almost every truly cryptic and bizarre thing has been given some measure of explanation or meaning within 10 episodes, as opposed to the 20 mentioned above. Yes, if you just started watching, that means that the Alternate Universe thing will get explained very soon.
  • This is a big part of what makes FLCL such a Mind Screw. Naota (and the viewer by extension) is essentially dropped into the middle of some huge, epic Space Opera story and almost never has any of the events or backstory references explained to him in a fully coherent way. In keeping with with the coming-of-age themes, the broad experience of the show is comparable to being a young kid growing up while some war is being fought in a foreign nation, with your only understanding of it coming from the adults in your life who barely know any more than you.
  • My Hero Academia: Shoto Todoroki's backstory reveals he has three siblings. The second oldest, his sister Fuyumi is introduced after the Sports Festival and their middle sibling, Natsuo, is introduced when the manga is about 180 chapters in, but their oldest brother is not even mentioned. In chapter 192 when Natsuo refuses to hear to the apology of their Abusive Parent Endeavor, hints finally start being dropped, including that the older brother is named Toya and "something" that happened to him by which Endeavor is (rightfully or not) blamed for and that has fomented their mother's breakdown.
  • The Hidden Cloud Village in Naruto was introduced long after the other four major ninja villages. The only proof of their existence was that a small number of Cloud ninja applied for the Chunin Exams early into the series, and after that, they were completely absent for several important arcs. The Hidden Cloud Village was even nonexistent among the Akatsuki, an alliance of villains from various ninja villages who have disowned their home villages in protest. This becomes a plot point later on after the Hidden Leaf Village is destroyed by Akatsuki leader Pain and the village leaders gather together to discuss how to stop them. As the Akatsuki has no Cloud ninja, they've never attacked the Hidden Cloud Village, so the village leader makes it clear he has no reason to get involved.
  • Negima! Magister Negi Magi:
    • A visual one: in the splash page from the first chapter of the manga, look closely at the center. Zazie Rainyday has claws. 250+ chapters later, this is still unexplained, as is everything regarding Zazie. It finally appears in the story proper in chapter 298.
    • The Magic World is filled to the brim with this type of stuff, with people referring to all sorts of races, animals, places, and phenomena that don't happen here.
  • The first thing everyone knows about Pokémon: The Series is that most Trainers dream of becoming a Pokémon Master, however over the entire course of the series it's never once discussed how one actually obtains this title until the very end with The Pokémon Company outright refusing to elaborate.
  • Puella Magi Madoka Magica:
    • A very subtle one. When Mami explains why Witches are bad, she mentioned them luring people to suicide and causing fights to break out in certain places. The second type of bad influence is never seen in the anime.
    • It's also hinted that she knew Kyoko, and Kyoko's past — but this is actually confirmed in a Drama CD.
    • Several are found in in the manual(s). The official website describes three witches who never appeared in the anime, because only their familiars did. We don't even know what they look like. Then we have the revelation that Walpurgisnacht is only a nickname. It's real name is only listed as "?????".
      • Of course, Mami also mentions that Witches cause "natural disasters" in addition to the suicides. And Word of God about Walpurgis is that it's actually a Witch that grew stronger by combining with other witches.
  • In Psycho-Pass, there are very occasional references to the fact that some great catastrophe has happened and Japan, with the aid of the Sybil system, is one of the few relatively normal nations left.
  • Slayers has a hierarchy of gods and demons distributed over four universes. Only some of these deities are described, others are named or merely implied. Nothing is known about the demons Chaotic Blue and Death Fog, for instance, and less than that about their opponents. Fanfic authors have, naturally, expended much effort to fill the gaps.
  • Sound of the Sky is rife with this trope. Most of the back story can be divided into two categories. There's the information that was lost forever during the Great Off Screen War, which isn't explained since none of the characters are aware of it. And then there are the things that all of them know about, which isn't explained since the characters have no reason to exposit out loud about it when speaking to each other.
  • Yokohama Kaidashi Kikou is the Slice of Life story of a Ridiculously Human Robot named Alpha running a small cafe during the twilight of humanity. Numerous mysteries are touched upon but absolutely none are explained fully, either because they have nothing to do with the story as previously outlined, or the characters are just as much in the dark as the readers.

    Comic Books 
  • Astro City uses this trope a lot, especially in the earlier volumes when the universe wasn't so fleshed out. There are constant references to heroes, villains, and incidents that the readers have not seen yet - and sometimes never see, since the story is more about how people think and live in a superhero world than about the actual exploits of the heroes. The author, Kurt Busiek, uses this trope a lot in his work - the same treatment is given to his magic-replaced-technology World War I story Arrowsmith, among others.
  • ElfQuest used to do this, but over the years, people Running the Asylum have started to fill in most of the gaps. Whether they should have bothered or not is a matter of some debate.
  • The League of Extraordinary Gentlemen does this constantly to fill in the gaps between the novels that the characters first appeared in and the actual LoEG comics themselves. To the point where a reference guide for all of the bits in the first collected comic was three times the thickness of the comic itself. One panel could have two pages worth of 'This is the X from Y', especially in the League’s museum base.
  • This pops up in another work by Alan Moore, Promethea. There are several references to adversaries and events from Promethea's past that are never seen or elaborated upon. The Shadow Queen however is probably the most notable since she is referred to several times without any details about her nature or ambitions revealed to the audience.
  • A Republic comic showed a Geonosian hive on the ice world Zaadja where several Mandalorian corpses were embedded into the walls. At the time of writing both races had an alliance with the Confederacy which would rule out any logical reason.
  • Writer Tristan Huw Jones would pepper his Tales of the TMNT stories with these, particularly when it came to characters.
  • James Robert's Transformers stories (The Transformers: Last Stand of the Wreckers, The Transformers: More than Meets the Eye...) tend to mention things, events, and places that are often very slowly elaborated upon or explained over time, if at all.
  • New Avengers (2015): During issue 6, the Avengers of the future mention the "Eternity Wars", which had some part to play in Hulkling becoming what they proclaim "King of Space", before adding that it's apparently some time away. Then Collapsar hurriedly asks Sunspot to forget he ever heard anything. The follow-up series U.S.Avengers mentions it again, with the future Captain America saying only that it was "worse" than Zero Day, when pretty much every major hero died at Thanos's hands.
  • Scrooge McDuck made many such references in comics by Carl Barks, which were intended as pure throwaway references to give the impression that Scrooge has lived a long, exciting life as an adventurer and businessman. Many years later, Don Rosa took many of Barks's offhand references and used them as the basis of The Life and Times of Scrooge McDuck.
  • The Ultimates: Bucky mentioned one of his daughters: Sharon Carter.

    Fan Works 
  • Deconstruction Fic Challenge of the Super Friends: The End has the Legion of Doom enter another universe. Cryptic references are given constantly to this world's past and how it got to be that way, but nothing is outright stated, leaving the reader's imagination to connect the dots. The characters are just as baffled as the reader.
  • In the Doctor Who fanfic Gemini, one of Ax-Crazy Serial-Killer Killer Captain June Harper's signature trick-shots is based on a "Taska Venkman" series of spy movies.
  • Because it's a series of vignettes in anachronic order, Ghosts of Evangelion has tons of these. Many get resolved in later chapters. However, there's a pretty big time skip with no chapters set between 2047 and 2080. In those last chapters, characters refer to a great many events that occurred during those decades without explaining much detail. For instance, Asuka and Shinji's daughter Ryuko refers to her children and grandchildren, but we don't know how many she has, whether she's happily married, or much else about her personal life. It also seems that some characters have died in the interim since they'd be expected to be present otherwise, but the characters don't spend time discussing things they'd all know already.
  • With Strings Attached is loaded with these, both overt and subtle. Examples include:
    • The Idris' attic is filled with artifacts that don't quite belong there, notably a stack of books in several different languages.
    • The Deep Gap. What created it?
    • All the crumbling towns and cities of Baravada. Shag and Varx toss off a line about how the Dalns gods are somehow responsible for them, but don't elaborate.
    • The Tayhil invasion. What exactly happened during that?
    • The Wizards' University, where Grunnel once taught and where Brox is currently doing research.
  • What About Witch Queen? has some, mostly used to expand the world. For example:
    • Tampere Empire is mentioned a few times as the biggest country in the region and a neighbor to both Corona and Arendelle.
    • There exists Far East. Tampere focuses on politics there and Southern Isles have ambassador there, but nothing else is ever said.
    • Southernmost Lands, an apparent stand-in for America of Era of Discoveries, with Mayincatec names and kangaroos, where everyone can allegedly start a new life.
    • Non-geographical examples include the Noodle Incident that caused Hauser to be Reassigned to Antarctica and hate Ferdinand, as well as some event in the past that caused Southern Isles to secede from Confederacy.
  • In The Mansionverse, no one precisely knows where the Haunted Mansion itself came from, nor what happened to The Old Gods.
  • Pokémon Reset Bloodlines has these aplenty. When it grew into an Expanded Universe, many of them were explored in sidestories:
    • At the beginning, it's revealed that Professor Oak made the world a better place 40 years before Ash awakened in the Reset timeline. The details at first are mostly unknown, save for the fact that thanks to his efforts, Pokémon are for the most part less agressive and more tolerant of humans. The story also drops an early hint that he and Professor Hastings from the Ranger Nations are friends and often work together in secret, despite their nations being in a state of cold war with each other. The Oak & Hastings Gaiden reveals that they worked together using technology behind Hastings's Capture Styler to develop a machine capable of pacifying aggressive Pokémon. However, they agreed to keep the bigger specifics a secret and have Oak take full credit for it.
    • There's also the aforementioned Great Offscreen War between Trainer nations and Ranger nations. Not much has been explained beyond the following points:
      • They ended decades ago and both sides are currently in a cold war state.
      • They were horrible.
      • The Draconids of Hoenn ended up allied with the Ranger nations as a result of territorial disputes with Sootopolitans, and this causes problems in the present day for Hoenn.
      • The incident that caused it to explode was the attack of a Gyarados school and the disagreement over catching or relocating them somewhere else so they wouldn't hurt anybody.
    • Georgia goes through a mental list of gym leaders and Elite Four who had to be removed for committing crimes shortly after she was introduced. In order of increasing severity of their crimes, a Flying-type gym leader who was a Peeping Tom, a Bug-type gym leader who was a home invader and burglar, a Normal-type Elite Four who was involved in rigged matches, a Poison-type gym leader who committed sabotage, a Ghost-type gym leader who committed several murders and a Dark-type gym leader who was the leader of an Apocalypse Cult. The Ghost-type gym leader was elaborated on, and it turns out he was responsible for murdering Georgia's parents as a Serial Killer, thus providing the motivation for Georgia to become a Buster.
    • An infamous criminal known as Twenty Gyarados Bill is cited as the cause of the current limit for six active Pokémon per trainer. His story is explored in his own gaiden.
    • The Fisher Clan are stated to have the Victreebel family as their signature Pokemon, with the clan winning many battles with them in the past. The Jeanette Interlude sidestory elaborated on that and it turns out the reason Victreebel is their signature Pokemon is because the founder of the Fisher Clan was a Victreebel Bloodliner.
    • In the Big P Pokemon Race Interlude, Lara Laramie says her family has lived in harmony with wild Pokemon since her grandfather's time. The Laramie Gaiden explores how Lara's grandfather decided to establish the Pokémon reserve.
  • The My Little Pony fic The Black Stallion doesn't explain what "nyru" are. All that's known is that they hunt ponies.
  • Kreadian Funk: When first meeting Dracobot on a roof, Girlfriend takes note of the body tape near the air vents, alongside a pair of shoes with a note, questioning if a Murder-Suicide occurred on the roof. Dracobot has no clue over the implied incident, at most expressing surprise that it's all left as is. The incident in question relates to his death back when he was human, but he has since forgotten the incident and prior life upon becoming Dracobot due to his creator/mother purging that memory.

    Films — Live-Action 
  • The Adventures of Buckaroo Banzai Across the 8th Dimension is littered with allusions to characters we never meet and adventures we never hear anything else about, artifacts left over from the writers' original plans for a multi-media franchise, which never panned out. A lot of the ones in the film are explained in the novelization. On the other hand, the novel is written in a way to make it appear to be one episode in a much, much larger universe (that is, one is to presume that 20 or 30 other such episodes came before it), and contains a huge number of references to "previous stories" that don't actually exist.
    New Jersey: Why is there a watermelon there?
    Reno: I'll tell you later.
  • In Airplane!, neither Striker nor any of his fellow crewmates will ever forget that day over Macho Grande.
  • Blade Runner: "I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched C-beams glitter in the dark near the Tannhäuser Gate. All those moments will be lost in time, like tears in rain. ... Time to die."
  • Escape from New York: The line "You flew the Gullfire over Leningrad, didn't you?" hints at Snake's past and a possible war with the Soviet Union. Also the fact that everyone thought he was dead for some reason.
  • Rollie from F/X: Murder by Illusion regularly drops names of movies he'd worked on when he or Andy re-purpose equipment from those films to foil the opposition (e.g. "smoke pots from Hellraisers").
  • It's implied early on in The Goonies that Mikey's gotten his friends in trouble before the film; Sloth is heard saying "I don't want to go on another one of your crazy Goonie adventures!", but no further details are provided.
  • While Jupiter Ascending is actually pretty good at world-building with background references and a surprisingly interesting universe, one reference in particular feels cryptic. Caine, the part-wolf part-human super soldier, is said to have ripped the throat out of an Entitled, yet he doesn't remember the incident taking place and apparently was informed of its occurrence by his mentor, Stinger. The only indication that it actually happened is that he was court-martialed for the crime, and is no longer a skyjacker. Who the Entitled was, the reasons for it occurring, and why Caine is said to have done it in a fit of rage when we never see him acting out of rage at any point in the movie, is never expanded upon.
  • Pirates of the Caribbean:
    • Jack Sparrow makes several non sequitur references to his past exploits (e.g., "And then they made me their chief.", "Clearly you've never been to Singapore.") that enrich his character. The sequels try to tie the movies together by creating plot points out of them.
    • When we actually do get to Singapore we never find out exactly what Jack did to offend Sao Feng, so this trope appears again.
    • Also, Elizabeth's speech on Black Sam's Spit: "But you're Captain Jack Sparrow. You vanished from under the eyes of seven agents of the East India Company. You sacked Nassau port without firing a shot. Are you the pirate I've read about or not?"
    • The former again has some references in additional media, such as Pirates of the Carribbean: The Legend of Jack Sparrow we see such examples as Jack sacking Nassau port (actually by seizing control by taking advantage of an existing crisis). However, Jack is lampshaded as an Unreliable Narrator, so matters may not be as they seem.
  • The Platform: Brambang and Baharat know each other from outside of The Hole. Brambang speaks as though he was Baharat's teacher at some point, but no specific details are given.
  • Rio Lobo: When Hendricks is first mentioned, McNally refers to him as "Blue Tom" and mentions chasing him several times but never capturing him, although whether this is refers to Hendricks being a Civil war guerrilla or a pre-war outlaw is never mentioned.
  • A mook in Ronin (1998) asks Jean Reno's former spy "Don't I recognize you?" He replies "Vienna" and shoots him. It's not relevant to the plot at all.
  • Shredder Orpheus offhandedly mentions Axel's time serving in the Great Contra Wars, and that back in 1986, a nebulous year in relation to the movie's timeline, Orpheus was a member of "Latent Death Wish," a black metal band.
  • Star Wars:
    • Upon its original release, A New Hope was a prime example of this, full of name-drops that have nothing to do with the plot but which combine to make the fictional world feel boundless and lived-in. References to the Imperial Senate, the Old Republic, "big Corellian ships" and the spice mines of Kessel are a few examples. Scenes that were cut in the original release, such as Han's confrontation with Jabba the Hutt, also make things like Greedo's confronting Han over something he did to wrong Jabba seem bigger. Every single throwaway line has been since filled in to ridiculous levels of detail by either the prequels or the Expanded Universe.
    • Ironically the Expanded Universe has never introduced any ship to match Han's line about the "Imperial starcruisers" that are "big Corellian ships" (he may have been referring to Corellian Corvettes. However, this seems unlikely, as they weren't predominately used by the Empire, and, while big, were nowhere near as huge as Star Destroyers and the like.)
    • More references include the Clone Wars, "that bounty hunter we ran into on Ord Mantell...," the Kessel Run, "many Bothans died...," Han and Lando's history, etc.
  • Will and Ned from Unforgiven often talked about their old gang.
  • The Way of the Gun makes a few references "what happened in Baltimore," some apparently shameful event in the OBGYN's past that has left him with limited opportunities.
  • The term "Double D-anniversary" in What Dreams May Come. Christy and Annie are repeatedly referring to this event without giving an explanation until towards the end when we flash back to the scene where this term was coined:
    Christy: Today is kind of a D-Day. "D" for decision, I guess. About divorce.
    Annie: That'd be two D's, wouldn't it?
    Christy: I stand corrected.


By Author:

  • Isaac Asimov:
    • Foundation Series: The Fifth Seldon Crisis gets disrupted by the Mule during the events of "The Mule", while the Sixth and Seventh Seldon Crisis are never mentioned in Dr Asimov's works. Foundation's Edge opens during the successful resolution of the Eighth Crisis (with Hari Seldon appearing during Founding Day to announce exactly why they made the right decision), and characters refer to the Plan having been on track since the Kalgan War (which wasn't a Crisis and was covered), making it clear that all three happened, but only the Eight has any detail on its nature or resolution givennote .
    • The Gods Themselves: No detail is provided on an event that killed about 4 billion people: "Just about the time the Lunar colony was being established, Earth went through the Great Crisis. I don't have to tell you about that."
  • Paolo Bacigalupi never really provides descriptions or actual expositions of his countless settings. While it was somewhat understandable when he was in short stories and novelettes, as seen in his Pump Six and Other Stories anthology, once he started to write books, all the world-building is still done by off-hand remarks in dialogues and tiny snippets of information in narrative, going as far as giving a name-drop as all that is to provide information. Piercing together details about his recurring settings is a favourite past-time of his fans.
  • The Brightest Shadow: Common, both in terms of characters referring to parts of the world not immediately relevant, and several epigraphs that refer to highly ambiguous events.
  • H. P. Lovecraft stories make repeated, throwaway references to fictional books and locales, but there's little evidence that the man himself had any unified vision in mind. His pals also did the same, throwing out cryptic Shout Outs to Lovecraft and each other's works. Enticed, the readers wanted more, and piecing together such references is part of the fun of the Cthulhu Mythos.
  • J. R. R. Tolkien was a master of Worldbuilding, working on his Middle-Earth world from about WW1 until his death. The Lord of the Rings is full of lovingly crafted and referred-to details, many of which are left unexplained, whose stories first got public with the posthumous publications of the earlier stories.
    • One thing Tolkien knew from his studies as a linguist and English teacher is that some of the old myths recreate the Cryptic Background Reference effect entirely by accident, when the relevant poems or stories are lost — the medieval Finns probably had an explanation of what a Sampo (from The Kalevala) is, for example, but it didn't survive the Middle Ages.
    • Then there are some things which never got elaborated on, even posthumously, like in The Hobbit when Bilbo makes reference to "the wild Were-worms in the Last Desert." Nothing remotely similar is ever even spoken of again.
    • "Far, far below the deepest delvings of the Dwarves, the world is gnawed by nameless things."
    • Half of fun of reading Tolkien is this. Go read The Silmarillion and go back and read The Lord of the Rings. Now revel in all the references most people didn't get the first time around. That part of the song Aragorn sings in The Fellowship of the Ring about Beren and Lúthien? Now you know the whole story. Bilbo's song about Eärendil that Aragorn seemed to find so cheeky to sing in Rivendell? It was about Elrond's father (and mother) who he hasn't seen in five thousand years and probably dredged up some bad memories about the ransacking of his home when he was a child by the sons of Fëanor. The list goes on.
    • The Second Prophecy of Mandos, which describes what the end of the world will be like, is referenced (though not by name) in virtually all of the canonical stories of Middle-earth. However, the prophecy itself does not appear in canon — only in Tolkien's earlier drafts for The Silmarillion.
    • Unfinished Tales also fleshes out several of these including the Cats of Queen Berúthiel that Aragorn mentioned during the journey through the Mines of Moria and the other two Wizards of the five Saruman brings up in his rant at Othanc.

By Work:

  • In the Mad Tea-Party scene from Alice's Adventures in Wonderland, The Mad Hatter proposes the riddle, "Why is a raven like a writing-desk?" Some time passes before Alice, the Hatter and the March Hare all admit that they can't find the answer. This did nothing to stop readers from persistently trying to find answers such as "Edgar Allan Poe wrote on both." Although Carroll himself eventually came up with the answer "Because it can produce a few notes, though they are very flat; and it is nevar put with the wrong end in front!" Or "They both have inky quills".
  • In the NaNoWriMo novel And Then There Were Monsters, some of the monsters mentioned in the text are explained in Father Mallern's journals. Most are not. Dire cattle, for example, and referenced a few times, but never seen, and in the end all we know is that the only similarity they have with normal cattle is that they still have four legs.
  • Alien characters in Animorphs often allude to various other species or situations that have nothing to do with the plot:
    • For example, early books would sometimes list random species the Yeerks had supposedly enslaved, though practically none of them are seen except for Hork-Bajir, Taxxons and Gedds.
    • There's also a whole subplot happening off-scene with a planet called Anati: apparently the Yeerks knew very little about it (including whether or not it was inhabited) and sent Visser One to conquer it, but she wound up failing for some unknown reason.
    • "The Five," the mysterious race responsible for hunting the Venber to extinction. Ax doesn't know where they came from or why they called themselves that, but they have since also vanished, possibly due to the Andalites of old giving them a taste of their own medicine.
    • At the end of book 41, the Bad Future Jake was experiencing turns out to be a psychological test conducted by an unknown being, for no obvious reason but curiosity. We never find out who was running it.
    • Crayak, a being who straddles the line between Sufficiently Advanced Alien and Cosmic Horror, was evicted from his galaxy of origin by an even more powerful being.
  • The Mechwarrior Dark Age novels (based on the BattleTech game world) made references to events that had occurred in the 65-year Time Skip since the last published BattleTech novel. The result was a lot of terms used in general discussion that had no explanation - The Jihad, the Ruins of Gabriel, Apollyon, the Master and so forth. Since then, new BattleTech fiction has begun to explain some of this.
  • Charlie and the Chocolate Factory has Mr. Willy Wonka noting that Loompaland, the homeland of the Oompa-Loompas — and a country none of the other characters have heard of — is a Hungry Jungle full of "hornswogglers and snozzwangers and those terrible wicked whangdoodles" without explaining what exactly those beasts are (besides very hungry). This isn't surprising, as Mr. Wonka himself has a never-explained Mysterious Past and is Inexplicably Awesome. (For one thing, between the original novel and its sequel, he's apparently managed to travel the world without being recognized for years, and has knowledge of other planets and alien races. Also, the 2013 stage musical plays this concept for laughs with throwaway lines that reveal that he used to go to raves.)
  • C. S. Lewis's The Chronicles of Narnia:
    • Mr. Tumnus has a collection of books, one of which is Is Man A Myth? It serves no purpose to the story other than world building and further setting up the Faeries Don't Believe in Humans, Either trope.
    • The Voyage of the Dawn Treader: The protagonists meet a magician, who is later revealed to be personified star who was sent to earth as a punishment. On being asked what possible crime a star could commit, they are simply told: "it is not for you, a Son of Adam, to know what faults a star can commit." The reference gets even more cryptic when Eustace comments that in their world stars are balls of flaming gas and is told that even in our world, that is not what stars are, but only what they are made of.
    • Aslan's father, the Emperor-Beyond-The-Sea, is mentioned but plays no direct role in the plot. Presumably the reason he's there at all is because Aslan, being a Jesus-equivalent, needs a father to complete the reference.
    • There are plenty of Always Chaotic Evil species in the setting, but there are a few unelaborated-on references to some of these species being in Aslan's army.
  • Part of the charm of the early books of Chronicles of the Kencyrath is that the main character is a member of a race with ten thousand years of history, but our glimpses of this history is as through a glass darkly because the main character already knows her history and doesn't feel the need to monologue about it. The later books have filled in many of the references, but far from all of them.
  • In the Codex Alera stories, there are several mentions of a group called "The Children of the Sun" who were, it seems, wiped out by the Alerans relatively recently (historically speaking) and, as a last action, did something, somewhere, for some reason and now there's the Feverthorn Jungle in the middle of the continent, that no one can enter for reasons which are unexplained. Though we get a rough idea of where it is (middle southeast of the continent according to the map in First Lord's Fury) what makes the jungle impenetrable (even to the Vord) is unexplained. The Alerans idly speculate that if they could figure out what the Children did, they might be able to turn it against the Vord.
    • Also All There in the Manual, as Butcher explained it on the website. They're another sentient race (of plant-people, with Woodcrafting-like powers), who are now all dead, wiped out by the Roman legions shortly after they arrived on Alera (and hence before they had developed significant furycrafting). Of all the sentient races that have appeared on Alera, only the toughest survive the competition.
    • The Children of the Sun aren't the only ones to get this treatment. Late into the series, a character reminisces about other sentient races the Alerans have wiped out in their struggle for survival:
    The Children of the Sun were long since dead, their Realm rotted back into the Feverthorn Jungle. The Malorandim had been driven to extinction eight centuries ago. The Avar, the Yrani, the Dekh — all gone, nothing left of them but names that Amara dimly remembered from her history lessons. Once they had all been rivals and tyrants to a younger, smaller, weaker Alera.
  • The Cold Moons throws around references to the badger's Animal Religion but doesn't explain the mythology though. Some things are namedropped in passing but all that's clearly known is that: Their God is named "Logos", while their Satan/devil is "Ahriman". Their heaven is "Asgard" and it's stated that all species live in harmony in Asgard. "Sheol" is referenced but it seems to be a hell equivalent instead of a Jewish-style Sheol. Some badgers aren't prayed for upon dying and thus they become eternally Barred from the Afterlife in a place above the clouds called "Gehenna". "Elysia" is the pastures of heaven and is also used as a short-hand for an otherworldly paradise. Badgers have a group of ancient laws called "the Adamus" (which is only mentioned by name, in passing, in the final chapter).
  • In the beginning of The Dark Tower, the third-person narrator often makes references to historical events and figures, such as the fall of Gilead and John Farson, as well as important characters in the gunslinger's past. Many of these are clarified later in the series, further expanding the previously sparse world.
  • The story of Princess Nell in Neal Stephenson's The Diamond Age starts out like this, and Nell and the Primer spend the next decade or so expanding the references.
  • Often used in Discworld, with throwaway references to things like the politics of the Guild of Engravers (although that one eventually became The Truth), or the various notes on Sam Vimes' desk that he's too busy with the main story to deal with, creating the feel that Ankh-Morpork keeps running even when there isn't a story happening.
  • Two examples from Distortionverse:
    • The Tryadine Effect case which was solved by Veckert before the events told in Chapter 1 - La Notte che Cammina and resulted in the opening of the dome of St. Patrick SHIELD is never explained in details — only hinted at;
    • The bombardment of Moscow mentioned by Egon Kramers in Sabbie.
  • Domina:
    • Loads. The names of cultures and warlords are dropped without context, only to be explained a dozen chapters later. Since there's lots of Theme Naming and Shout Outs, the audience has some clues to figure out what the names refer to before they appear on screen.
    • The Dagonites get referenced every few chapters for hundreds of chapters, with no explanation. Even when Dagonite characters show up on screen, the other characters just note that they don't look as weird as they expected, and move on.
    • Space colonies are referenced as well. A refugee from a minor mutiny on the Chinese Shaohao station crash-lands at one point, and later it's mentioned that the Soviet Tsiolkovsky Station is the communications hub for the colonies. Ceres gets a few mentions (it's implied to be a factory colony), and someone says that a character is from "Lemuria, on Mars."
    • The fall of Eden is mentioned more than once as an important part of the city's past, but no context is given.
  • Stephen Brust's Dragaera books use this in massive amounts. Paarfi's novels are supposed to be historical fiction novels within the universe, so they assume that the reader is a Dragaeran who doesn't need additional explanations. Vlad sometimes seems to make the same assumption, but other times he explains common aspects of the world for the reader's benefit. Vlad will also make vague references to his various other misadventures outside of the scope of the current story without going into detail. Sometimes he says he doesn't want to digress, and other times he's simply cryptic. Some of these do get explained in future novels. Brust intentionally includes them as possible story hooks for future novels without planning on where they'll go.
  • The Dresden Files contain a fair amount of them, such as the reasons for some wizards not showing up to a White Council meeting in Chicago including "He got real married", "Living under a polar ice cap", and "Pyramid Sitting".
    • In a case that ultimately ended up a subversion; in the first book Harry mentions that Santa Claus is real, and implies he's terrifying. Fast forward fourteen books, and we finally meet him in Cold Days, and get a good idea of why Harry would have been scared of him in the first book.
  • Used fairly frequently in Herbie Brennan's The Faerie Wars Chronicles. Since most of the series is set in a fantasy realm with only two non-native characters present, references to simbala parlours, power outrages, border Redcaps, or The Reindeer King of Crippenmas are pretty commonplace. Some of these are given explanations in the glossaries, and a few end up connecting to the plots of later books, but many are left entirely unexplained.
  • Mercedes Lackey's Heralds of Valdemar novels have a handy store of ancient history at which to hint. Some characters (Vanyel, Lavan Firestorm) have had their own books, but she claims "Windrider" and "Sun and Shadow" likely will not, since they work better as distant legends.
  • The Hitchhiker's Guide to the Galaxy is littered with these, with allusions to far-off planets and some of their inhabitants that are never explored in-depth. For instance, Maximegalon is apparently a planet with a very rich academic history, although it's never visited; neither is Blagulon Kappa, a world mentioned off-handedly several times but about which even less is explicitly stated. On the character side of things, Oolon Colluphid is apparently a very prestigious writer and an acquaintance of Zaphod Beeblebrox's (as of the sixth book), and some of his books have been named, but he's never personally encountered. The same goes for Eccentrica Gallumbits, the triple-breasted whore of Eroticon VI, and ex-president Yooden Vranx, who would have been part of the first story arc, but the author wound up not going there. What's really interesting is that the many of the stars and systems he mentions are real, like Sirius. This amuses people with arbitrary knowledge of stars.
    • There's also a bunch of almost-correct ones. There is no real-life planet called Ursa Minor Beta, but there is a star called Beta Ursae Minoris.
  • In Clive Barker's The Last Illusion, the story mentions a botched exorcism attempt on Mimi Lomax which has scant but horrific detail. The novel "Everville" goes into this incident with more fleshing.
  • Loyal Enemies has vampire kingdoms, which are alluded to a few times, and the islands, which are somewhere in Beloria, but we don't even learn in what direction.
  • With the Monster Blood Tattoo series, D. M. Cornish not only strives to make the Half-Continent feel lived in with side comments and throwaway lines, but he has so many side characters who appear and reappear within Rossamund's narrative that it leaves readers thirsty for all the potential other stories that could be told. There is, after all, a reason why the glossaries in the back of the books can be a third of the physical book.
  • Much like the Sherlock Holmes example, the Nero Wolfe series by Rex Stout begins on terms of false familiarity, and vaguely references past cases that are never fully explained.
  • In Michael Ende's The Neverending Story, many vague allusions are made to the further adventures of secondary characters, always accompanied by the phrase, "But that is another story, and will be told another time." Needless to say, said stories have never been told.
    • Actually plot-significant, and gives the book its title. In the ending, Bastian is told he can't leave until every storyline he started up is finished. But given the rate uncompleted plots have been created (several story hooks get created for every one he finishes) he'd never be done. Atreyu saves him by taking on the task on his behalf. The movies leave this out, resulting in an Artifact Title.
  • Neverwhere is full of this. Particularly the Big Bad's motivation for sinking Atlantis. All we get is him shouting "THEY DESERVED IT!" Neil Gaiman's work has tons of this, but Neverwhere and Stardust are particularly big examples.
  • Used in the Old Kingdom books by Garth Nix, and not overused, either. He's mentioned in interviews that he's not really into world-building — he just makes everything up as he goes along.
  • Hannu Rajaniemi's The Quantum Thief features many references to cataclysmic events that shaped the world of the novel, but remain a mystery to the reader, and sometimes even to the characters due to lost historical records and memory manipulation. These include the Collapse that caused most people to abandon Earth, the Cry of Wrath, the Spike which somehow destroyed Jupiter, and the Protocol War. Some get elaborated in the later books and even become major plot points, while others remain a mystery.
  • In Raymond E. Feist's The Riftwar Cycle, there is a place called Roldem in the east of Midkemia. It is mentioned in a few of the books, and included in every map of the world, however over the course of more than 20 books, it is not visited at all. In fact, most of the information on Roldem comes from a single e-mail written in 1998.
  • The Rise of Kyoshi has a few mentions of Salai, who is listed alongside Yangchen as one of the greatest Avatars ever. Nothing else, including gender or nationality, is mentioned.
  • In the Sherlock Holmes stories, Watson is famous for this, often referring to other cases, such as the one involving "the giant rat of Sumatra, for which the world is not yet prepared". Some of these became stories in their own right (though usually not from Doyle's pen), but most remain unexplained.
  • Used masterfully well in Ulysses Silva's novel Solstice. There is exactly one incident where things are properly explained by the main character (even then, it's mostly clarification on things you've picked up). Everything else is left for the reader to figure out. And quite often, everything you thought you'd figured out turns out to be completely wrong, leading to many an Epileptic Tree until the very end.
  • A Song of Ice and Fire: The series is full cryptic background references to various events (the tragedy at Summerhall, the Tower of Joy, "The Rains of Castamere", the Blackfyre rebellion, the Ninepenny Kings, the Doom of Valyria, etc). As the series moves on, some of them have been at least partially explained. The map is a large example too: George R. R. Martin has stated that not all locations on the map of will be visited in the story. Consider the fact that no viewpoint character has yet visited (during the story, that is) the Lannisters' home Casterly Rock, or the Basilisk Isles that show up on the map of (part of) the Eastern Continent.
  • Gary Seven references events and races in Star Trek: The Eugenics Wars when Roberta asks him to justify whatever their mission is - some of which the audience has heard of, some of which were just made up. Discussed when Roberta complains that she's never heard of these events or races and can hardly check up on them.
  • Following the tradition of the films, the Star Wars Expanded Universe and Star Wars Legends make references of their own, some of them mentioned or expanded on by others, some of them never mentioned again. It gets downright fractal at times. Try hitting Random Page on Wookieepedia and see how far you can get before finding an article with one line of description and one or two appearances.
    • A discussion on the Falcon from the first book in The Thrawn Trilogy, Heir to the Empire:
      Lando: She's as safe now as she's ever likely to be. Don't worry about that.
      Han: You know, that's almost exactly the same thing you said back on Boordii. That botched dolfrimia run — remember? You said, 'It'll be fine; don't worry about it.'
      Lando: Yes, but this time I mean it.
  • The Stormlight Archive has lots of these, references made by characters to things that happened in their pasts, references to the history of the world etc. Given that only the first book of a ten book series has been released, and that Brandon Sanderson loves to collect loads and loads of Chekhov's guns it's highly likely that a lot of them are just waiting to go off.
  • In the Super Mario Bros. Nintendo Adventure Book Pipe Down!, Princess Toadstool mentions that in the past (around the time of her ancestors) there were things far worse and more powerful than the Koopa Kingdom, but no elaboration is offered as to what she means by that.
  • Tailchaser's Song:
    • Tailchaser's Song notes that cats have three names: a "heart name" that is given by birth and is only used by those the cat is very close to (such as family or mates), a "face name" that is given in a Naming Ceremony at three months of age and is used by almost everyone, and a "tail name" that is a private name that a cat must discover on their own. Tail names are never discussed with anyone and it's noted that many cats nowadays don't ever find their tail name. Face names like "Tailchaser", "Fencewalker", and "Whitewind" use Common Singing words, while heart names like "Fritti", "Tangaloor", and "Firsa" use Higher Singing words. It's never mentioned what a tail name sounds like. Tailchaser might have found his in the final chapter, but it's never mentioned what it is, if he did.
    • It's mentioned early on that, upon reaching adulthood, a cat becomes a "hunter". This is not touched upon in other scenes and is never clarified. It's only mentioned that Tailchaser, who is not even a year old yet, is too young to be considered a hunter.
  • "The Tamarisk Hunter": The events surrounding Lake Havasu City are referred to in-story, but beyond involving water and possibly the destruction of a water plant, it's not clear what they were.
  • Thursday Next:
    • Lampshaded continually in the series in the form of Textual Sieves. Roughly every other time they're mentioned, someone asks what they do, and are told that no one knows, since they're so sparsely described. Thursday asks Miss Havisham, and in turn Thursday 5 asks Thursday how textual sieves work and the given explanation is "it's never properly explained."
    • There's plenty of other examples, such as the "Boojumorial" of Jurisfiction agents lost in action ("Boojumed", or deleted), the views across the wilderness to other Great Libraries for other languages, the City of Adventure that is the Well of Lost Plots, previous disasters in the BookWorld (apparently, Titus Andronicus used be "a gentle comedy of manners", but increasingly bad behaviour by the characters turned it into the "the daftest, bloodiest play in all of Shakespeare"), and items in Thursday's TravelBook that haven't yet turned out to be Chekhovs Guns, such as String TM. There's even more examples in the Outworld, which to Thursday is the real world. Genetic engineering means they've resurrected the woolly mammoth, but they don't have ducks; Britain was invaded by the Nazis during World War II and comedy musician George "When I'm Cleaning Windows" Formby led the Resistance, later becoming President-For-Life; The People's Republic of Wales; riots over art styles and literature; the weirder parts of SpecOps, and so on.
  • Warhammer 40,000: Sandy Mitchell's Ciaphas Cain books have loads, some of which get stories (a reference to hunting Tyranids on a hulk, now released as The Emperor's Finest), others are not (yet) fleshed out (his encounter with a Dark Eldar wytch, and time spent on a Tau world, for instance).
  • The Wheel of Time novels are full of references to epic historical events and heroes, and the landscape is littered with ruins and relics of bygone ages. Some of it gets expanded on and turns out to be important to the backstory, but a lot is just hinted at to give the impression that the setting is old and didn't just sit there doing nothing until the main characters arrived.
    • Even happens in-universe, with Birgitte and Mat (after he starts gaining access to the memories of his past life). Being ancient characters, they have witnessed events that happened THOUSANDS of years prior and have been losts to the mists of time, so nobody around them has any idea what they're talking about when they start spouting off references.
    • And because time in the setting is cyclical, many of the references are in fact to actual historical events in our time, but with the details garbled by the passage of the ages. Many of the oldest songs and stories will actually be surprisingly familiar to readers.
  • World War Z is in love with this trope, with casual mentions of numerous events during the Zombie War that never gets explained in-depth.
  • Worm and its sequel Ward have many cryptic references, some of which receive later explanations or story arcs. Of the ones that have not:
    • The Sleeper is the most prominent example that remains cryptic, an S-class threat whose presence causes an entire dimension to be written off for reasons that are so obvious to everyone that the reader gets no explanation.
    • Why Canberra, the capital city of Australia is covered by a giant dome has never been explained, even when many other cryptic references have been addressed via word of god.
    • The Three Blasphemies are an S-Class group of supervillains mentioned to be terrorizing Europe. This wouldn't be too remarkable except it's been suggested that they aren't human.
    • The Machine Army is a group of self-replicating Killer Robots that have been mentioned to be a persistent threat but have only been briefly featured in the narrative once. Who built them and why has been left unanswered.
  • In The Epic of Gilgamesh, when Ishtar, Goddess of Love, asks Gilgamesh to be her new mortal boy toy, he angrily rejects her, listing a number of her past flings whose stories ended in disaster when she tired of them. Some of his examples seem pretty self-explanatory, but a few are very weird and unexplained (apparently one of exes include a lion and a horse). Presumably, most of these references were pretty clear to the original Sumerian audience, who would be well-acquainted with these other stories, but no records of them are known to exist today, creating an extreme form of Parody Displacement.
  • Encryption Straffe: Most details in the history or status of the major technology, locations and factions could only be inferred through insider dialogue, including those crucial to the plot. For instance, somehow the key technology to human-machine interface operates on... The power of hate.

    Live-Action TV 
  • Andor:
    • Saw lists a host of Rebel groups and condemns them all as being "lost". These begin with names and causes that Star Wars fans would recognize such as Separatists (who had attempted to break away from the Republic in the Clone Wars before Palpatine turned the Republic into The Empire), neo-Republicans (who want to restore the Republic), and the Ghorman Front (Ghorman being a planet that is colonized by the Empire, and where Imperial troops would massacre protestors several years after the first season of Andor), and continues on to the Partisan Alliance, sectorists, human cultists, and galaxy partitionists — all names and causes of unknown significance, other than that they're organizations or ideologies that have reason to oppose the Empire.
    • When Skeen chastises Nemik for falling asleep on watch duty, he lists several rebel cells which he says would have tortured or killed Nemik for such a lapse. The only one that is recognizable to Star Wars fans is Saw Gerrera, the rest are all a mystery and have never come up in any Star Wars lore before Skeen mentioned them.
  • Babylon 5 subverted this trope quite often, given that it was all plotted out in advance. For instance, the fates of all the previous Babylon stations seemed to be a case of simple world-building, to stress how dangerous the universe was. But then we learned what happened to them: Three destroyed, one vanished. Then the vanished one shows up again, having been Unstuck in Time. Then it gets even deeper, when it's revealed that Sinclair, The Captain in the first season, was in fact that Minbari prophet Valen, after he'd traveled back in time to provide the Minbari with the space station they desperately needed to win a war, which also helps to explain the random weirdness of Delenn becoming half-human. Other factors, like the unstable politics of Mars, also come up again in later seasons to be fleshed out. Other things, however, were left to the imagination. Such as what it was about Vree eating habits that disgusted G'Kar so much that he considered sitting next to them to be an insult to his entire government.
  • Buffy the Vampire Slayer did this sometimes. For example in "The Prom", Wesley mentioned the "Machash Wars".
  • Burn Notice does this a lot by mentioning various ops the main characters have done before the start of the series.
  • In Doctor Who, all bets are off. The Doctor will routinely spout off about unexplained spatial phenomena, utterly bizarre alien cultures and references to the Last Great Time War and too many other things to even think about listing. These are often expanded on in books or audio dramas, and occasionally later in the show itself.
    • Stories with the Third Doctor (and occasionally others) often make mention of an unnamed "monk" or "hermit" the Doctor knew long ago. The audience finally met the monk in the Third Doctor's final story. Whether the "hermit" was the same person has been the subject of much debate among fans.
    • It's virtually guaranteed that whenever the Doctor meets the Master, they will talk about their childhood and various parts of their own backstories and identities, which of course will never be explained because of how important the mystery behind them (as well as the Time Lords and Gallifrey as a whole) is to both characters.
    • Characters other than the Doctor are known to do this, too. For example, Captain Jack Harkness of Torchwood fame. This mostly has to do with various sexual exploits, but he does mention actual bizarre past experiences. Random side-characters can do this too, usually to the Doctor or one of his companions, with the assumption that they're from the same period/place, and know what they mean.
    • We know about Torchwood 1 (from the Doctor Who episodes "Army of Ghosts" and "Doomsday") and Torchwood 3 (from Torchwood). But the mysterious disappearance of Torchwood 4, and why Torchwood 2 is one guy, called Archie, above a bank in Glasgow, ("A very strange man") will probably never be revealed.
    • The audience's desensitization to this is exploited in "The Time of the Angels". While walking around the old mausoleum of Alfava Metraxis, the Doctor rambles on about the natives, and particularily how they had two heads and outlawed self-marriage at some points. Then he realizes that the statues around the mausoleum only have one head. Because they are all Weeping Angels.
  • Unintentionally done in the TV series adaptation of The Dresden Files, where things that are explained in the books are referenced, but are never explained in the series. It is possible they would have been, had the show not been canceled after a season.
  • Fargo: In season 1, characters like Lou Solverson and Ben Schmidt make references to the Sioux Falls massacre of 1979, which we later see for ourselves in season 2.
  • Game of Thrones: Events surrounding Lyanna's abduction and her eventual death remained a mystery until late in the series. Some of the events transformed into foreshadowing after the 6th season finale revealed she died giving birth to Rhaegar's son, whom her brother adopted and renamed Jon Snow. In-universe, the abduction remains a cryptic reference even after the audience (and Bran and Sam) get a complete explanation in season 7.
  • How I Met Your Mother: There was much speculation as to the origins of the goat in Ted's apartment, which is mentioned in season three but abruptly dismissed with "oh wait, that was on my thirty-FIRST birthday". Fans had a whole season to wonder, but the actual explanation was, perhaps inevitably, a bit of a letdown.
    • The title itself refers to How Ted Met the Mother of His Children. It took until the end of season 8 before we saw her face.
  • LazyTown: The first episode has the Mayor lamenting how awful the town is, and notes that when the town was previously in trouble, they would call for help from a guy with a big number 9 on his shirt. With Sportacus being number 10, the implication is that Number Nine was the town's previous savior who left or disappeared for unknown reasons. This is even more cryptic with the fact that Robbie knows who Number Nine was while the Mayor only read about it.
  • Leverage has several of these, such as the named cons that we never see the team run, like the "London Spank," the "Genevan Paso Doble" and the "Apple Pie," which is a "Cherry Pie" but with lifeguards. Also, there's what Nate did at the Russian border. Word of God says that he may have technically hijacked a train, but that hasn't been mentioned on the show and likely never will be.
    • We've also seen the team coming back from jobs - one in Mexico where Parker picked up a lot of pinatas, and one in the Caribbean that went wrong in several different ways - without hearing much about what those jobs actually were.
  • In The Lord of the Rings: The Rings of Power, there are many events and characters from Silmarillion that can only be alluded because of the treat between the Tolkien Estate and Amazon, in which only the Appendices of The Lord of the Rings can be fully adapted. The War of Wrath and fall of Beleriand are never named in the prologue, but key scenes are shown from them. Luthien and her hound Huan have statues carved in wood in a shrine build for the fallen Elves in Lindon, yet they are never named. The Harfoots settles temporary somewhere around Rhovanion, in a place full of ruins and destroyed statues, hitting that there existed once a mysterious advanced civilization, and there is no clue of who they were.
  • In addition to the character backstories seen in flashbacks, Lost has included a number of throwaway references that have captured fan imaginations, including Sawyer's "Tampa job" and Sayid's Basra incident.
  • Marvel Cinematic Universe:
    • Daredevil: People in New York City only ever refer to the alien invasion of 2012 as "the Incident". Lampshaded when the realtor guiding Matt and Foggy around their future office space for Nelson & Murdock brings up that their office escaped damage during the invasion:
      Matt Murdock: The, uh, "Incident"? Is that we're calling it now?
      Susan Harris: Well it sounds so much nicer than "death and destruction raining from the sky, nearly wiping Hell's Kitchen off the map."
      Matt Murdock: Shorter, too.
    • Each of the other Netflix shows uses "the Incident" too when talking about the invasion, showing that it's become pretty much a citywide thing (and possibly so they can differentiate it from 9/11).
  • Merlin occasionally references the Ancient Kings and the High Priestesses, who were apparently embroiled in some sort of war for supremacy before Uther came to power.
  • In Stargate SG-1, one of the four great races is the Furlings, who are never shown in 10 years of episodes (though a parody in episode 200 shows them as small furry creatures, looking somewhat like Ewoks). The non-appearance of the Furlings has become something of a Running Gag, since the parody starts with surprise to even meet them, and ends with the Furling homeworld being destroyed.
  • The constantly expanding Star Trek universe is replete with this one and usually two or three are generated per episode.
    • A common theme in Star Trek: The Original Series and early Star Trek: The Next Generation is having a character list one or two examples from real-world history and adding a fictional example from the setting that is implied to be similar by association but is never elaborated upon or referenced again.
    • The other most common thing are events that occurred in the fictional gaps of time between the various eras (Approximately 100 years elapsed between Enterprise and The Original Series, 15ish years for TOS and The Wrath of Khan (The Motion Picture being close-ish to TOS' present), and 80ish for The Original Series and The Next Generation. Significant things happened during those periods that are frequently referred to, but almost never shown on screen ("What happened to the Enterprise-B?" and the Earth-Romulan War being some of the big ones.) The Expanded Universe naturally latches onto these things like crazy.
    • In the Star Trek: Voyager episode "The Omega Directive" it's mentioned that the titular directive was established after an accident with the Omega Particles happened to Federation scientists in 2269. The fact that 2269 is in the middle of Kirk's five year mission, and this neither references an episode of the original series, nor mentions any involvement from the Enterprise (but doesn't discount it) makes it all the more cryptic.
    • They Double Subverted this trope in regards to a specific alien race. Since TNG, there has been mention of an alien race called the Breen, though all that was known about them is that their homeworld is very cold. They finally show up in DS9, but in full body environmental suits that completely disguises their appearance, and nothing at all about their society is revealed. A throwaway line in DS9 suggests that they are extremely secretive by nature, so that not even the people in the shows know much about them.
    • Star Trek: Deep Space Nine referred in a couple of episodes ("The Adversary" and "Home Front") to a race called the Tzenkethi. All we learned was that their leader was called the Autarch, and that they'd previously fought a war with the Federation during which Ben Sisko served as first officer of the USS Okinawa under then-Captain Leyton. The EU used this as a jumping-off point for several novels, including making them a major player in the Typhon Pact following the Dominion War, while Star Trek Online based an arc on them that segued into another arc based on a CBR from Deep Space Nine, the reemergence of the Klingons' ancient enemies the Hur'q.
  • The Wire shows the city of Baltimore had its own mythology in its criminal underworld. Similarly, at the wake of Ray Cole, Jay Landsman alludes to major cases Cole cracked in the past, that are references to movies Robert F Colesbury, the actor playing Cole, had written and produced in real life.


    Tabletop Games 
  • Magic: The Gathering uses this a lot in their Flavor Texts. Many of the early ones were given explanations later, but not all - for example, we still don't know whose uncle Uncle Istvan is supposed to be.
  • Unknown Armies. Even if you manage to read through every single supplement and piece together as much as you can, there are still a lot of holes. But, since the game's major theme is a world of mystical insanity seething just below the facade of normalcy, it's generally agreed that it just wouldn't make sense if everything made sense.
  • The current incarnation of the Necrons in Warhammer 40,000 was inspired largely by a throwaway line by Rick Priestley about "the quiescent perils of the C'tan" which "lay beyond the Gates of Varl". References were quietly worked into the game over the years in the form of the C'tan phase sword and phase knife, until the release of the first Necron codex where the C'tan were finally revealed as the "gods" of the Necrons, indescribably ancient and evil monsters which feed on suns.
    • There are also the two "missing" Space Marine Primarchs and their Legions. Every mention of the twenty Primarchs lists numbers II and XI as "All records deleted", and EU works have consistently refused to give any detail about who they were or what happened to them.
      • The Horus Heresy series of novels and audiobooks have touched on the subject obliquely, ranging from intimations of an accident at the gestation stage, to something so shameful and terrible that the Imperium refuses to acknowledge them, even when daemon-worshiping, civilian massacring, backstabbing psychopathic unrepentant bastards are still listed in the records (admittedly, usually with the note "Explode planet on rumour of presence", but still). The exact details have never been revealed and are unlikely to be either, this is lampshaded by characters telling each other not to even think about discussing the details.
      • The closest we get is a throw-away line saying that the Space Wolves had previously been ordered to attack a Space Marine Legion.
      • The Rainbow Warriors chapter of Space Marines remains incredibly cryptic even decades after their first appearance... Which featured one of the Sisters of Battle gunning one of their members down with no accompanying explanation. They were not mentioned again until years later when White Dwarf published a map with a "record deleted" message stamped across their honeworld.
  • Now that the game numbers something like 50 books, there's very little in Rifts that was mentioned in the first book that hasn't gotten a description by now. One of the biggest examples was the Republicans, which was an off-hand mention in the first book about a technological society living in the ruins of Washington, D.C. It was the subject of several unofficial Sourcebooks (called Netbooks) until they were finally described in the Expanded Edition of the original Sourcebook. There are still a few things here and there that have gotten mentioned but still not shown. The most notorious is the permanently-open Rift in Calgary, Alberta, and the monster kingdom that's developed there, as well as others like the Blood Druids of France.
  • Psionics: The Next Stage in Human Evolution: Rose Klein (AKA Mama Bear) gets one in Tomorrow's Starlight. It’s never explained what the "Albuquerque Incident” was, but it was apparently enough to get her a maximum threat rating from The Shop.

    Video Games 
  • Historical references abound in Assassin's Creed, some of which can come off as cryptic background references. But Assassin's Creed III has two unusual examples:
    • In the downloadable-content side-story "The Tyranny of King Washington." In the regular story, the PlayStation 3 version of the game included extra missions in which Connor tries to stop Benedict Arnold from betraying West Point to the British, which were omitted from the others. In the DLC, which is set in an alternate timeline but with Connor aware of the events of the main story, he remarks that he finally got Arnold back for West Point when he kills him at the end of the first chapter. Arnold says that he has no idea what Connor is talking about, since in this timeline he never turned coat and thus never betrayed West Point. To Wii U, Xbox and PC players who didn't get those missions, it comes off as a cryptic background reference, merely something that happened off-screen.
    • In the main game and some others, conversations can be overheard in towns—particularly from heralds—referring to real historical events, such as a town crier in Assassin's Creed III informing citizens of events taking place in Egypt that have no bearing on the story at all. In Brotherhood—set in Renaissance Italy—a herald refers to the recent discovery of the New World and its native peoples.
  • BlazBlue has six legendary heroes. Hakumen is playable, Jubei and Valkenhayn Hellsing show up as NPCs and the rest are shown only as silhouettes until Continuum Shift. It adds Terumi Yuuki to the playable list, adds Platinum (one of the three souls in her body being that of Six Heroes member Trinity Glassfield) to the NPC list and reveals that Nine is dead. Valkenhayn and Platinum later became playable through DLC and expansions, and the silent villain Phantom is heavily implied to be a brainwashed Nine.
    • By the end of the fourth game not only have they all been introduced, they're all playable as well: Jubei, Nine (killed and resurrected as "Nine the Phantom"), Yuuki Terumi (in three different forms no less), Valkenhayn, Hakumen, and Trinity (in Platinum's body)
  • Cave Story. There are references to shared histories between characters, and to a war ten years ago with armies of robots from "the surface" attacking the Island, and to three bearers of the Demon Crown prior to the Doctor. There's just enough information to construct a vague timeline for the backstory, but it's obvious that there's more to the history than what we're told. When asked for further information about the game's world, the writer has said that he himself doesn't know.
  • Demon's Souls, the Dark Souls series, Bloodborne, and Elden Ring are almost entirely bereft of traditional exposition, and the story of each game must largely be pieced together and inferred from item descriptions, level design, and the like. There are occasional characters better informed than the Player Character who will provide some precious information, but they generally prove untrustworthy. Hidetaka Miyazaki claims the inspiration for this style of storytelling came from him attempting to read Western fantasy novels as a teen despite having a limited grasp of English: he could only understand certain passages, many of which referred to objects or events described in passages he couldn't read, thus turning explained plot points into this trope.
  • From the first Devil May Cry game, searching around and interacting with specific objects in Mallet Island will reveal small details regarding the abandoned island's long dead inhabitants and their cultish worship of Big Bad Mundus. None of it ever amounts to anything significant in terms of gameplay, and some fans believe it to be a holdover from the game's early development history as a Resident Evil title. Dante himself will occasionally, humorously lampshade that none of the island's history has any bearing on his quest.
  • Dragon Age: Origins has a lot of background material that isn't wholly relevant to the games' plot. Moreso in the sequel since the game takes place on a more personal level. Some particularly interesting bits of background are that the Primeval Thaig was apparently part of an ancient dwarven civilization predating the Deep Roads, which had temples and worshiped gods (and that the Primeval Thaig was ruled by a "dwarf so foul the Stone rejected him" and covered in evil red lyrium that drives people insane), that at least one Eluvian leads to "another place - beyond this world, beyond the Fade", that Flemeth is, at least according to Morrigan, something other than merely a mage or an abomination, and that the qunari must have arrived in Thedas (the continent where the games are set) from somewhere because they only showed up three hundred years ago, but no one knows where they came from.
    • More subtly, there is the whole Codex business: in theory, it should offer exhaustive explanations and backstories of in-game events, items, and characters. However, in practice, one cryptic reference explanation contains three more references that don't get explained.
    • The Warden can do this during Witch Hunt, only vaguely hinting to their new companions their precise relationship and reasons for searching for the Witch of the Wilds. Particularly noticable if Morrigan was romanced, where Ariane eventually comes to realise that the Wardens cryptic statement that "She has my child" didn't mean that Morrigan had kidnapped their child as she'd assumed, but actually because Morrigan was the mother of their child. Furthermore, she later figures out the nature of their relationship, asking the Warden if they are aware they subconsciously play with the ring on their finger when they think no-one is looking. After the Warden explains it's part of a pair shared with Morrigan, Ariane is genuinely amused when they fervently deny that this means they're married.
  • The Elder Scrolls series has thousands of years of backstory material that is only hinted at in the games, either through dialogue with various characters or in the many in-game books.
  • Fable and Fable II gives us all kinds of elaborate references to places you never go, ancient tribes and cults, and legendary heroes, none of which are ever seen.
  • Far Cry 3:
    • The casino chips you find in loot are described as being from "the Jeni Soleil Casino Cruise heist." This is not explained any further.
    • Privateers will sometimes say "At least I'm not on that island with the dinosaurs." This may have been foreshadowing that ultimately went nowhere, as in January 2015 Ubisoft said that a Jurassic Park-type island with dinosaurs was one of the possible locations for Far Cry 5.
  • Final Fantasy VIII does it occasionally, most notably with the sorceresses. For example, "Great Hyne" is mentioned as their progenitor and source of their powers, but you never learn who exactly that was, save for some legends told by NPC you're likely to miss.
  • Final Fantasy XIV does this a lot. As it is an MMO, some of these references became fodder for patches and the Heavenward expansion, which focuses on the Dragonsong War, a war between Ishgard's theocratic society and Dravania's dragons that was waged for a thousand years by that point, and brings more of these with the Warriors of Darkness and bits and pieces found in the Dusk Vigil and Azys Lla's museum. The fallen Allagan Empire also started out as such only to get some explanations with the Binding Coil of Bahamut and Crystal Tower dungeons, as well as the aforementioned Azys Lla which explains how it became a Soiled City on a Hill and how its actions up to that point resulted in a Calamity that ultimately wiped the Empire out entirely. In addition, there have been seven umbral eras and seven astral eras, but the only points that get even a description that comes close to being in-depth are the ends of the third (the aforementioned fall of the Allagan empire, leading to the Binding Coil dungeons and Crystal Tower raids), fifth (a war between two societies of mages that triggered a worldwide flood, leading to the Shadows of Mhach raids and frequently referenced in the Scholar and Red Mage quests) and sixth (the fall of Dalamud that ended the 1.0 content cycle) astral eras, and the seventh umbral era (the five years between Dalamud's fall and the initial storyline from the A Realm Reborn relaunch).
  • Foxhole's lore primarily exists of small bits of flavor text for maps, along with statue plaques, forgotten notes, and descriptions of view points that reveal tiny snippets of the setting.
  • Golden Sun games have a lot of this kind of information that you can gather from the various NPCs or furniture in the various towns, regarding the political and economic situations of your surroundings, gossip about local leaders, what the cuisine and culture are like in each place (in some places extending to religious beliefs), optional content you can explore, and once in a while some obscure lore tangentially related to the plot.
    • Dark Dawn takes this a whole step further with the major characters themselves discussing some stuff in relatively major cutscenes that isn't at all involved in the plot of the game, like the three races of the Precursors, the modern geography and political unrest around Morgal and Bilibin, and Kraden's messenger pigeons. Fans were annoyed that this cut into plot and character development, which were less consistent than in the previous two games.
  • Guild Wars has a few, though many of them ended up being explored in the Bonus Mission Pack.
  • Kingdom Hearts enjoys this quite a bit. The meaning of the phrase that started the series, "You are the one who will open the door to light" has still not been fully explained. In the first game, Sora closes the Door to Darkness; in the second, he finds Kairi's letter, which does open a path back home, but as he's not the one opening it technically, it's unknown just what the phrase means.
  • The driving force behind The King of Fighters, Orochi, qualifies. The only things we know for certain are 1. it involves a horribly evil destructive power, 2. the clan is absolutely fanatical and will stop at nothing to raise their god, 3. the Kusanagi, Yagami, and Kagura clans were the ancestral foes of Orochi, 4. but the Yagami betrayed the alliance, causing their flames to turn purple. Everything else is a confused mishmash... some artifacts we never actually see (until Ash Crimson starts pilfering the current clan members of their powers in the 2003-XIII arc), "maidens" who may or may not have been slaughtered, Kyo getting preferential treatment causing Iori to go all emo or something, a bunch of sealing and unsealing attempts, "battle energy", earth worship and "returning all to nothing", Rugal of all people chosen as a guinea pig, self-destruction, betrayals, counter-betrayals, etc., etc. Worst of all are the numerous plot points and outright sequel hooks that are flat-out dropped, such as a heavily-implied rift between Rose and Adelheid at the end of XI.
    • It doesn't even end there. KOF mythos designates Orochi as "Gaia's Will"; it's not only the progeny of the earth mother of Greek myth (bizarrely enough), but her self-appointed guardian. Gaia herself has yet to directly appear in any capacity and is only mentioned in regards to her familial ties with Orochi and her creation of humanity, assuming she's mentioned at all. This begs the questions of where exactly is Gaia in the present, why did she create a being so fanatical in its duty to her that it vowed to destroy humanity (the very beings Gaia herself brought to life), and why is she practically non-existent not only in the face of her child's actions, but when dealing with earthly matters as a whole. More headscratching ensues if you take into account the greater SNK universe; one of the tournament regulars is the reincarnation/descendant of Gaia's great-granddaughter.
    • Those from the Past's goal to obtain the power of Orochi by breaking its seal (yet again) comes across as this, as it's never clearly spelled out during the Tales of Ash what their leader Saiki wants to do with it. Not even in XIII, the climax of the saga wherein said leader makes a formal appearance and all of his scheming comes to fruition. Side materials reveal that the group is more or less the Western European equivalent of the Orochi clan and Saiki needs Orochi to power an artifact known as the Gate (which does appear in XIII) so he can travel back in time and change the flow of history so as to prevent the cult from suffering a horrible loss to their human adversaries (presumably Elisabeth's ancestors, thus explaining her personal vendetta against them and the repeated, equally cryptic mentions of her and Ash's "mission"). Sadly, little of this is explicitly mentioned in the game proper, and Saiki's shady, self-serving nature (complete with the implication that said explanation doesn't hold water) opens up grounds for further discussion.
    • If there's one plot point in KOF that adheres to this concept more than anything else, it is—without a doubt—the Dragon Spirit. That subplot first reared its head back in KOF '99, with Kensou and Bao shown to be vessels for an otherworldly power coveted by the mysterious Ron (former leader of the Hizoku clan of assassins and a former member of NESTS, the villainous cartel of which KOF's third Story Arc centers on). Fast forward to XI and XIII and all we know is that Kensou has apparently mastered its powers (much to Ron's approval) and Ron has unspecified ties to Those from the Past (as Saiki alludes to Ron having warned him of Kensou in their pre-boss fight dialogue). We know nothing of the Dragon Spirit's origins or why Ron has his sights on it, although it can be inferred that this has something to do with Ron's betrayal of his clan. This is mainly an effect of the plotline mostly being put on hold in lieu of Those from the Past's machinations; with several Hizoku members being introduced to the cast since 2000 (including Ron's son Duo Lon, a semi-important supporting character from 2003 onward) and the Tales of Ash having come to a close with XIII, it's possible the next arc will finally revisit these story elements and elevate the ever-elusive Ron to main villain status.
  • From both Left 4 Dead games, the only parts of the story that are completely laid out for you are from the single 4-chapter comic ("The Sacrifice"), and the short character bios that each of the Survivors get (neither of which are found in-game). The rest of the plot that's given to you will only be through random (often campaign-specific) character dialogue, about 99% of which isn't even guaranteed to trigger (usually requiring multiple play-throughs if you want to catch everything), or occasionally from significant pieces of the map, but most of all from the writings on the walls of different saferooms (and occasionally elsewhere) of other people who have passed through that area, describing bits of their experiences as messages to others, agreement or disagreement with what the military is/was doing, just how bad CEDA failed, how fast somebody changes into a zombie after being infected, and so forth, but not even those people are in 100% consensus about whatever's been going on, and nobody really has any idea what even started the whole thing. We might get some answers eventually, but given Valve's reputation for making third installments, it's probably not going to be any time soon.
  • Mischief Makers treats all the characters as already established, and new characters are often brought in with the assumption that they've had encounters with main character Marina in the past.
  • In Pillars of Eternity II: Deadfire Rekke is a living Cryptic Background Reference, a Hidden Character who is found clinging for dear life to flotsam near the endless storms east of the Deadfire and doesn't speak any language known in the region. It's strongly implied he comes from beyond the storms of Ondra's Mortar, a place where no known explorer has ever sailed before. He eventually learns enough Aedyran to confirm this and tell of further details about his homeland, Yezuha, including its enigmatic, monotheistic God, but enough of a language barrier exists that he can't fully explain the cryptic hints he gives.
  • There are a number of unofficial Pokémon that are clearly alluded to exist in the setting, but are not capturable, or for some, ever even seen by the player:
    • One of the most well-known examples is the original dragon that was split into the Tao Trio. We don't know what it looked like, as it's not possible to restore it.
    • The Legendary Beast trio were brought back to life by Ho-Oh. We don't know what they were originally before being resurrected. The only hint we've been given is silhouettes that look more like normal, real-world dogs than any existing Pokémon.
    • Shellder has an alternative evolution that can clearly be seen on Slowbro's tail and Slowking's head, but is not capturable by the player by itself. note  A leaked demo revealed it was originally programed in as an attainable Pokémon separate from the Slowpoke line, but was removed for a unknown reason.
    • Cara Liss restores some fossil Pokémon for the player. However, she does it by frankensteining the front half and back half of separate species, the result depending on what exactly you give her. (This is a reference/joke on how in real-life early paleontologists mismatched bones, especially in Britain where this region is based; incidentally, she's wearing mismatched shoes and has mud on her face to further emphasize how careless she is). For some reason, the game does not allow you to obtain these Pokémon in their correct, original complete state, although there is plenty of speculative fanon and fanart.note 
    • Kangaskhan are always seen with babies in their pouch. These are clearly its pre-evo, but they are not obtainable separately by the player. If the player breeds a Kangaskhan to try and get it, the egg simply hatches into a adult Kangaskhan with a baby already in it's pouch. The leaked Gen 1 alpha suggests it was supposed to be connected to fellow "Child and Parent" species Cubone and Marowak.
    • Genesect is a fossil Pokémon bought back to life and altered to have a cannon on its back. What it looked like in its original state is unknown.
    • Many fossil Pokémon are part Rock-types. It's not officially confirmed, but Fanon is that many of these Pokémon gained the Rock-type because of being resurrected from fossils, and that in their original state, their types and thus, forms, were different.
    • Arbok is noted to have more than 20 variations of the markings on its body. Some of these can be seen in different games (as unofficial form differences?), but not all of them.
    • The Sealed Chamber in Ruby & Sapphire, where you learn how to find and potentially capture the Regi trio, has the following (translated) inscriptions around one of the rooms: 'In this cave we have lived. We owe all to the Pokémon. But, we sealed the Pokémon away. We feared it. Those with courage, those with hope. Open a door. An eternal Pokémon waits.' This is the only reference to any backstory of this kind in the entire game.
  • In Quern - Undying Thoughts, Maythorn's journal mentions "Oshwald, the capital world of the United Empire" but does not provide much in the way of information about it beyond its six ancient gateways.
  • The Saboteur: What is the trouble that made Sean unable to return to Ireland? Who are the enemies he made there? What did Sean's father do there exactly? Where did Sean learn to use explosives? What was Sean doing in Budapest when he met Skylar? It's possible that the time period immediately before the literal "Troubles" in Ireland is referenced, and this would also explain how he learned to use explosives.
  • Sid Meier's Alpha Centauri includes many fictional quotes from the game's characters and other people in the game's world. These as well as a handful of other game elements are the only inside look we have into what life on Planet is really like (unless you read the novelizations, anyway). Many details are left to the imagination, such as, "What exactly is 'nerve stapling', anyway?" Somehow, it works.
  • Silent Hill is another prime Canon Fodder series, as this trope tends to be the only source of available information. With one exception (Walter Sullivan, the main enemy in Silent Hill 4, was originally mentioned in a newspaper article in Silent Hill 2) none of them are explored or elaborated upon, and in the case of some this is probably for the best.
  • Star Trek Judgment Rites plays this In-Universe when Kirk and his team board the alien ship Compassion, which is currently attempting to land on top of a Federation colony. The ship's mentally-unstable computer provides some information about the ship's origin and purpose, alluding to an ancient society that got rid of its mentally-ill by sending them on a long round-trip, to be cured by future advances in medicine once they get back. Unfortunately, none of it is complete, and a lot of it is contradictory both with itself and with things observed around the ship. Pretty much all of the team's actions revolve around getting inside the computer to repair it, and when they do, the computer appears to "sober up" and provides more answers... which are still contradictory. Unfortunately, in the end the whole thing turns into an Un Reveal when the computer suddenly admits that it was all just an illusion - a test - and the episode has no real ending.
  • Street Fighter II contained the mysterious line "You must defeat Sheng Long to stand a chance," prompting much debate on just who "Sheng Long" was and a rumor that he was an unlockable character. It was eventually explained that the name actually just referred to one of Ryu's attacks, not another person. But still...
    • Then there's Bison/Vega crowing about how "The Ancient One" couldn't face him. And Fei Long dedicating his art to "the master and his son" (actually a reference to Bruce Lee, Fei Long's expy source). And those three college students who inspired Sakura to take up fighting. And anything at all involving Gill. That's not even touching on the whole sordid tale of how Charlie Nash's death happened, or for that matter, where it happened, which has so many possible explanations by now, it qualifies as a Multiple-Choice Past.
    • Undoubtedly the biggest issue involving said Sheng Long, the canon ending to the first tournament. Other than the basic fact of Ryu hitting Sagat really, really hard, we're never going to know for sure what actually happened. The most likely scenario, in fact, involves Ryu connecting with Sagat's chin (the usual one hit KO location for MMA); any blow to the chest forceful enough to put away a brawny heavyweight would've left a much larger scar than what Sagat's currently sporting.
  • This happens once a game in the Summon Night: Swordcraft Story games: random NPCs come into the scene and reference something that would make sense as part of a longer plot but which you don't know about. ("I would gladly fight to the death to follow the last orders of Master Shinrai!" ...Master who?) How much of this is the result of this actually being a spin-off series of a larger plot that never made it outside Japan isn't immediately obvious to English-speaking players.
  • Super Robot Wars lives on this trope - Throwaway references became major plot elements in later games - such as Lemon's last name, and referring to a 'Beowulf' who piloted a 'Gespenst Mk. III' (Alt Eisen) - obscure references to the previous game, where the protagonist's theme called was 'Steel Beowulf' and his unit was revealed to have been a modified Gespenst Mk. I considered for mass production. And many, many more.
  • Team Fortress 2 has this to an extent. It began with the Excuse Plot of two rival corporations hiring mercenaries to fight over seemingly trivial objectives. Each mercenary has a distinct and interesting personality, but virtually no Back Story is given and they didn't even have any real names. Since the release, more of the history leading up to the game has been revealed, and additional bits about some of the classes have come forward.
    • Potentially, the increase in backstory has only increased this trope. Why does the Announcer control both sides, pitting against each other for no apparent reason? What are her connections to Saxton Hale and the Redmond and Blutarch families? Why is friendship such an alien concept to her? What will the Engie do with all that secret deposits of Australium? How did the Soldier get a magician as a roommate? (All this only appears in the addition material. If you're content to run around reducing other players to bloody chunks it won't bother you. After all, reducing each other to bloody chunks is the point of the game.)
  • Thief II: The Metal Age During the missions, you occasionally hear and read references to "the Baron", who's absence has allowed Sheriff Truart to assert his dominance over the city. No detail is given about who the Baron is or why he is absent, but this little detail creates the feeling that the game is set in a small corner of a much larger world.
  • Touhou Project is filled with this trope. It ranges from important things like the Great Suwa War, Yukari's (first) invasion of the moon, and the sealing of Gensoukyou within the Hakurei Barrier, to miniscule details like Marisa's relationship with her father, the dispersal of the oni, and Rumia's ribbon. Add some Hufflepuff Houses and rampant Shrug of God, and the result is an entire series that is prime Canon Fodder.
  • Several, both minor and major are scattered throughout the Trails Series. Some particular standouts.
    • The Divergent Laws. References to weapons carried by Ouroboros have very rarely been described as having special properties granted to their wielders by the Grandmaster of Ourboros. At the climax of The Legend of Heroes: Trails in the Sky SC, Loewe shatters Weisman's barrier around the Aureole, an object that was gifted by the goddess Aidios and has been explicitly said to be capable of granting miracles. Whatever the heck these Laws are, it was enough to completely derail the plans by the Big Bad and defies everything else we're told about what should be the most powerful objects in the setting. A quote by Loewe remains the only explanation we're given over the course of 8 games. "The sword granted to me by the Grandmaster. Just like your staff. It's a demon sword forged through the Divergent Laws."
    • The Thirteen Factories are an oft-mentioned source of where the Enforcers regularly obtain Archaisms, but it's still unknown who oversees these factories, where they're in operation, and how projects on such a massive scale have gone unnoticed and rival what any of the large companies in Zemuria can make.
    • The Great Collapse is mentioned by characters to be what caused the downfall of the ancient Zemurian civilization, but more than 14 years of games later and it's still unexplained what this was, exactly. It could be anything from wars, Things Man Was Not Meant to Know, the collapse of moral and social restraint, a natural disaster or series of natural disasters, and so on. Whatever it was, shortly there after every one of the seven Sept-Terrion disappeared from the world, birth rates plummeted, civilization crashed, and the survivors were thrown into a centuries-long Dark Age.
  • In Tsukihime, during the final encounter with Nrvnqsr, he and Arcueid have a conversation on things that you don't learn until much later in the game, or in supplemental materials. This is intensified by the use of code-like terms, such as referring to Roa as the "Serpent of Akasha".
  • It seems that Valve is fond of this trope. The Half-Life series is almost entirely built out of it. What were the various departments at Black Mesa researching? What do those vast Combine machines actually do? How did those corpses end up where they are? Who was the Rat Man? Who was Lazlo? The vast majority of the story is told by implication only.
    • The "Rat Man" from Portal was later explained in the Lab Rat comic that was released alongside Portal 2.
    • Most enigmatic and underexplained of all are the Half-Life series' villains. The Combine are some kind of confederation of enslaved and cybernetically-enhanced alien species, but so far we know almost nothing of the scope of their empire, or even who's running the whole thing. Are the grub-like Advisors the leaders of the organization, or merely some middle-management? Their history and motivations remain completely unexplained, though their MO seems to be the assimilation of alien species and extraction of resources.
    • And then there's the most important and mysterious character in the entire series, The G-Man. Not a single word of explanation has been given for where he came from, the motivation behind his actions, the origin of his god-like powers, or who his ominous Employers may be. Given that he caused the famous Resonance Cascade that led the Combine straight to Earth, you might think he's working for them. But the Combine have consistently treated him as an enemy, and he does help Gordon expel them from Earth. What connection does he have with the Vortigaunts, and why can't he stop screwing with protagonists? His actions are so seemingly contradictory that his purpose and backstory could turn out to be anything.
  • All throughout Vampire: The Masquerade - Bloodlines, you get lots of background hints of events and backstories that have little to no relation to the power struggle in Los Angeles that makes up the main plot, such as news reports about apparent Signs of the End Times or quests where you meet/help out heroes of other stories. It all gives you the sense that everything you're doing is nothing more than a sideshow on the outskirts of a much larger and stranger secret war that you've barely seen a glimpse of.
  • Xenogears. A lot of the backstory involving dead civilizations and their predecessors from space but you only know (sparse) details from supplementary materials. Squaresoft was hoping to make sequels based on this information.

  • Girl Genius does this a lot, helping to give the sense that it's an alternate history defined by the presence of mad scientists.
    • Among the more notable are references to what things were like before Baron Wulfenbach took over Europe, what the places ruled by less pleasant Sparks are like, and the fact that there are multiple popes.
    • Occasionally they'll also drop and/or hide names we're familiar with in places we can spot them, showing how those individuals are different in this version of history (the most prominent one is actually reasonably well known, but he's addressed by his surname where we the reader are typically familiar with his given name alone). It's Rembrandt van Rijn.
    • Sanaa's adventurous backstory is one of the few that is likely never going to be explained further.
    • A side story taking place after the main story does this. We know Agatha is settled in as the Heterodyne and Mechanicsburg is safe, but everything else is left quite vague. The Empire is referenced in a way that implies Mechanicsburg has to worry about their laws, but it's deliberately unclear who is in charge of it, what Agatha's relationship to them is, and how that relates to Mechanicsburg. The Storm King isn't even mentioned, but it could be his empire they're talking about instead of the Wulfenbach one.
  • One story arc in The Inexplicable Adventures of Bob! involved a lot of clarification of throwaway details like this from earlier in the series. We've finally seen Butane the planet of dragons; we've gotten a minimally technobabblish explanation of what borfomite actually does; we've seen some court intrigue in the Nemesite Empire; Fructose Riboflavin is finally looking competent enough to explain how he got his terrifying reputation; etc.
  • Dresden Codak engages in this from time to time. We never learn anything more about Reverse Moses, other than that he once parted the city to escape Aqua Pharoah.
  • The Mansion of E often makes passing reference to things in distant parts of the Mansion's home country and continent.
  • Several of these in The Sanity Circus, such as references to other, as-yet-unmet Scarecrows. Luther and Steven have also made reference to other Instrumen they know called March and Jupiter.
  • Much of the draw of Kill Six Billion Demons is the lavish, imaginative Worldbuilding that regularly alludes to incredible events and people at work all around a main cast who rarely intersect with or expound upon them much.

    Web Original 
  • All over the place in the Whateley Universe, because the authors have a huge bible they're working from. So there are references to superheroes and super-teams we haven't met yet, and supervillains who are 'A-level threats' according to an international scale we haven't had explained either, and also tons of references to real-world things to show how close that universe it to ours. Some of these are All There in the Manual. A B-List is world-threatening, but your average supergroup can still maybe win. Maybe. If they're lucky. An A-list, you have to call in EVERYONE. An A-list is the kinda guy you have for a Crisis Crossover.
  • Also present in The Descendants, with characters mentioning minor villains they've defeated, superheroes in other cities, and seemingly pivotal moments in history that haven't even been explained in flashback. Whether or not they're just building up a Chekhov's Armoury, though, remains to be seen.
  • Dr. Horrible's Sing-Along Blog makes mention to other superheroes/villains outside the main characters, such as Bait and Switch, Johnny Snow, and Hourglass, although some of them do get actual "screentime" in the supplemental comics.
  • Limyaael's Fantasy Rants: Limyaael recommends that if you're going to use these for worldbuilding, use a lot of them, so the audience gets used to them as worldbuilding and doesn't expect them all to be plot points... and the ones that are plot points have the element of surprise.
  • The earlier volumes of RWBY were full of references. Some of them deliberate hooks, others the result of difficulty dropping exposition about things the characters already knew. Most of the latter got filled in later on, but the series has so far kept up a supply of new hooks to replace things that are explained.
  • In Dream Come True, the animals all live like normal (talking) farm animals. Yet, the horses mention the "Gypsy King" (who seems to be from another farm) and imply some sort of international society involving Gypsy Vanners. The farm animals act like they live in a kingdom, but none of this is ever clarified.

    Western Animation 
  • Adventure Time has many references to a Great Mushroom War that happened about a millenium ago, with characters visiting old destroyed cities of our present day, old technology being littered around, and the entire planet missing a huge chunk. The actual nature of it wasn't even discussed at all until halfway through the series, but it was easily inferred to be some sort of World War III that somehow turned the world into a Fantasy Kitchen Sink somehow before any explanation began to be given.
  • In one of American Dad!'s Christmas specials, taking place on the post-Rapture Earth, inhabited by demons.
    Stan: The open road is too dangerous.
    Jesus: What if we go through Sector 16?
    Stan: Sector 16? The perfect man just proposed the perfect way to die.
    Jesus: Fine! Then what about Sector 35?
    Stan: Sector 35? (scoffs) Sector 35 makes Sector 16 look like Sector 48!
  • DC Animated Universe:
    • The three-part pilot episode of Justice League shows the Big Seven superheroes working together as a team for the first time. This was Green Lantern John Stewart's and Hawkgirl's first appearance in the DC Animated Universe — and the established superheroes knew exactly who they were without any introductions, having apparently heard of their off-screen exploits or worked alongside them at some not-shown point in the past.
    • Similarly, a lot of the superheroes and supervillains in Justice League just show up with their origins unexplained (and often never explained) as well; The Flash, Red Tornado, Vixen, Gypsy, Star Sapphire, Copperhead, Black Manta, and Doctor Polaris are just a few examples.
    • Another big DC Animated Universe example - The Near Apocalypse of 2009, mentioned in Batman Beyond and Justice League Unlimited's Epilogue. Nothing is known about it except it was the last battle between the first Batman and Ra's al Ghul where Talia finally betrayed him for good. No other details are known about it, and so it has become a popular subject whenever fans demand more closure to the DCAU, although Word of God says they never really planned to cover the event in any of the animated shows, and at this point it does not seem like they ever will.
  • Futurama often makes fleeting references to events that happened in the thousand years between 1999 and 2999, such as Conan O'Brien losing his legs in the War of 2012, most videotapes being destroyed in 2443 during the Second Coming of Jesus, and the Sith War of 2865.
  • My Little Pony: Friendship is Magic occasionally referenced things that happened in the setting's distant past, particularly those before the advent of Celestia and Luna as princesses (and that in itself lasted for over a century before Luna's banishment 1000 years before the show begins), and then only in a roundabout way that suggests a loose series of events but no timeline.
  • One episode of Samurai Jack has the dual Villain of the Week Josephine and Ezekiel Clench frequently referring to "that boy from Kansas City" and talking as if he had put up the fight of their lives. Considering the two of them gave Jack the most trouble of any group of Bounty Hunters, this boy from Kansas City had to have been an equal to Jack or close to him. Of course, we never find out who he was or any details about him besides that he went up against the Clenches and was very difficult to take down.
  • South Park will occasionally mention weird origins for their various Monster of the Week, like that the Crab People were driven underground during "the Kindling Wars," or that Mickey Mouse spends much of his time in Valhalla.
  • Star Wars: The Clone Wars had the Death Watch start working for the Confederacy in one episode and planning to kill their leader Count Dooku during their next appearance, where they were stranded on a snow world. Why this was happening was never explained.
  • Steven Universe
    • The show is always making reference to things that happened in the past that involved Gems, in particular the Great Gem War for Earth. While the cause and purpose are eventually explained as the Crystal Gems splitting off from Homeworld, many of the fine details are only vaguely alluded to, leaving thousands of years of history to explore. Additionally, many hints about the Alternate History shaped by Gems are brief images the camera's quick to pull away from. Among other things, the geography of the this Earth is completely different from our own.
    • The Galaxy Warp is said to connect Gem-controlled planets to the Homeworld via Warp. Aside from Earth, there's a mentioned fifteen additional Warps that have been severely damaged, with nary a hint as to their names and possible native species. And there's also countless newer Warp Pads that have been constructed, as Earth's Gem technology is severely out of date.
  • Thunder Cats 2011 has the Cats searching for three stones of power, in addition to the Eye of Thundera. Where these come from no one knows. Also, the planet they live on is called Third Earth, and unlike in the original series, this one is heavily implied to not be our Earth, which means there must be a second earth. It's also implied that technology once existed in abundance even before Mumm-Ra's pyramid crashed there, which means it could be After the End.
  • Transformers:
    • Megatron in Beast Machines has a scar over one eye which he didn't have at the end of Beast Wars. Where did it come from? We don't know.
    • Originally used, then later became a subversion during the pilot of Beast Wars. Optimus Primal references "the Great War". Since this series was originally not meant to be too closely connected to the first generation, this was more of a lore reference for long-time fans of the franchise, and this trope for everyone else. As the series went on and the creators decided to make the G1 connection more explicit, the original intent faded.
  • The Venture Bros. features lots of The '70s style heroes and villains running around, we only see a handful of heroes but because of the big influence the Guild of Calamitous Intent have on the show we will constantly see cameos from lots of weird looking supervillains. How and when the Guild started is also kind of vague but it's implied that it was formed by or because of Doctor Venture's father or grandfather.
  • Young Justice manages to do this in a different way: back stories and origins often go unexplained, but will still be referenced. Your average DC fan won't be phased by characters mentioning the existence of Amazons or something called "the Guardians of the Universe," but it all adds up to a rather large, unexplored world.
  • The Trollz episode "Forever Amber" mentions the ancient Troll village of Angermore, who used their magic for evil but disappeared without explanation. It's hinted Simon might have something to do with it, but it's never outright confirmed.

Alternative Title(s): Whats A Secret Four, World Building Name Drop