Canon Fodder

Loose ends, unanswered questions, intriguing details, and Noodle Incidents left in Canon by the creators; these make good launch points for Fanon and Fanfic.

All active serials, especially ones with no defined endpoint, have intentional Canon Fodder because the creators need it to launch their own future storylines. Unexpectedly canceled works will be full of it, too. But even works that try to avoid leaving Canon Fodder will likely leave some accidentally.

Chekhov's Gun and its relations can be Canon Fodder if a sufficiently long time passes between introduction and use. Sequel Hooks are Canon Fodder by definition. Red Herrings are always potential canon fodder, especially outside of the mystery genres. Even Cryptic Background References specifically intended not to become fodder usually don't last long if a story gets continued longer than the creator expected or falls Off the Rails. Hufflepuff House is often a good source of Canon Fodder as well.

The more devoted the fanbase, the smaller the detail that can become tempting Canon Fodder.

If the creators of an active work take a piece of Canon Fodder and develop it contrary to how most of the Fanon based off that piece is going, Fan Dumb and related swearing at the creator can easily result. If the creators go a step further and actually use the Fanon's answer for Canon Fodder, it's Sure Why Not.

Not to be confused with Cannon Fodder. Compare Leave the Plot Threads Hanging. A Sub-Trope of Fanfic Fuel.

Anime and Manga

 * The author doesn't want to make a big deal of the Canon Fodder, but the fans of Axis Powers Hetalia are interested in how the "human" aspect of a nation-tan works, such as how they come to be (in the series, nation-tans start as children that appear out of the wilderness, and there is little other explanation). Many conversations and dramatic fanfics have been spawned from this.
 * My, Yugoslavia, you have lost weight. And changed your name, you say? Why yes, I'd love to meet your new siblings!
 * What's more, it is stated that nation-tans have parents and grandparents that preceeded them.
 * Fans like to know what happened to Prussia, the resident Ted Baxter Ensemble Darkhorse, since the Kingdom of Prussia doesn't exist anymore. He is presumably still alive and well, though, since he was able to make a blog and a Twitter account and Word of God says he lives in Germany's house now.
 * The American Civil War, and, by extension, any civil wars. Was there a Confederacy-tan, and if so, what happened to him/her? Or did Alfred develop a split personality?
 * In Martian Successor Nadesico, the mere existence of the Ancient Martians wasn't referenced until the last few episodes. Who they were was supposed to be explained "in the inevitable second season" (quoted from Ruri herself)...which was never made. Also unresolved was the Jovian/Earthling conflict, Akito's whereabouts, and—if you never played the Japan-only videogame, The Blank of Three Years—just what happened to everyone who crewed on the Nadesico before The Black Prince movie was made.
 * Good thing we have Super Robot Wars. Who knew the ancient Martians were related to the Mikene Empire, the Gradosians and the Boazanians?
 * Neon Genesis Evangelion: Did anyone actually know what SEELE's motives were until the movies came out? What about Gendo's?
 * Leliel being described as potentially connecting to other universes practically begs for Crossover fanfics to use it as a kickoff point.
 * In the final chapter of Ai Kora,
 * Digimon Adventure revealed that there was a group of Digidestined that saved the Digital World far before Tai(chi) and company came to the Digital World. To this day, not another word has been mentioned of them. Speculation of who they were continues to this day.
 * There's also the Cthulhu-like ruler of the Dark Ocean from Digimon Adventure 02 - the Ocean itself showed up a few more times during the season, and got a loose explanation in the finale as being a place where people's dark wishes come true, but the "Dark Undersea Master" is never seen or heard of again.
 * Code Geass has so much it's not funny, mostly due to the fact that the plan for the second half of the series was changed massively on the way to becoming R2. We still don't know what the Geass actually is, where Suzaku's "powers" come from, what C.C.'s real name and history are, or what the characters did before the series (though some novels deal with Lelouch and Suzaku's childhood just before the war, once Japan surrenders the story essentially pauses until the anime begins).
 * Recently subverted in One Piece; for years,
 * In Naruto, who raised Naruto until he could take care of himself? Who were the Fourth's enemies, and why did Naruto need to be kept in the dark about who his parents were? Do people whose last names we aren't given even have last names, and if so what are they?
 * For the longest time there were also the questions: What were the other tailed beasts were and who were their hosts? What happened on the night Naruto was born and the Nine-Tailed Demon Fox was sealed? Who was Kushina, and how did she become a Leaf ninja despite being from Whirlpool?
 * Puella Magi Madoka Magica reveals that . Fans promptly speculated on their backstories.
 * Three witches are mentioned on the website but never appear in the anime. Then there's  All There in the Manual reveals it's just an alias and it's real name is a complete mystery.
 * Bleach: Why is Isshin Kurosaki a Shinigami (possibly a captain)? How does he know Ryuken Ishida? How do the spirits in the afterlife "get sick" and "die", or even have "noble families"?
 * What happened during the thirty years of between the final two chapters of Hellsing?
 * In Rurouni Kenshin, the surviving members of the villainous Juppon Gatana are give secret deals from the Meiji government. Most notable is Ensemble Darkhorse Soujiro Seta, who has decided to wander around Japan for ten years much like Kenshin Himura and Makoto Shishio.

Comic Books

 * The Sandman leaves the reason for Delight becoming Delirium ambiguous with a couple of tantalizing hints, and it's probably the most-debated topic amongst fans. Another obvious Canon Fodder point is who killed the first Despair; all we know about it is that the person responsible is a he and will never stop suffering until the end of the universe. Some theories even tie the two Canon Fodder events together (e.g. Delight went mad with grief after the man she was set to marry killed Despair and was condemned to eternal torture for it).
 * Comics author Peter David has said (joked?) that he throws tons of loose ends into his stories deliberately, because he figures it's harder to fire him off a book when he has lots of story points still to resolve.
 * When you get down to it, what the hell was going on during the whole Cardinal Directions arc of Douwe Dabbert? Where did the portal cave come from, and the temples and the artifacts that are kept in it? Why did the cave overflow after Douwe's return? Worst of all, Douwe probably could have known it all - at the end of The Sea to the south, he lets a vase drop to the ground and walks away - only to the reader is it revealed that the vase contained a scroll about the cave.

Film

 * There are entire web pages and newsgroups dedicated to this issue in regards to Star Trek and Star Wars... and in many, if not most cases, both
 * It's amazing all the military capabilities fans of both take for granted in the absence of a scrap of evidence. One random example, you'd think "warp strafing" would be fairly common in Star Trek the way some fans talk, when it has in fact never been used in canon. In other words, canon fodder that doesn't actually exist, but still acts as a starting point.
 * The "Space Jockey" in Alien, which Ridley Scott will apparently be covering in two prequels (starting with 2012's Prometheus).
 * Elias Voorhees, the father of Jason Voorhees, who was only vaguely alluded to in the ninth film.
 * Kill Bill: Will Nikki Green get her own revenge on the Bride for her mother's death? Tarantino himself said that she deserves her revenge just as much as the Bride did.

Literature

 * The Lord of the Rings, pretty much anytime anything is said or done by anyone. Much of it tied in with his other works, which were released posthumously and constituted a veritable mythology generated by decades of writing and rewriting. Tolkien spent years cleaning up plot holes so tiny that most people don't notice them and there's still huge amounts of things that fans contest.
 * Older Than Feudalism: Notable examples of this occur within Homer's works. Most notable is the case of Aeneas: after Homer, numerous other authors made minor contributions to his story, and it became accepted tradition that he had travelled to Italy after the sacking of Troy. Centuries later, Virgil's Aeneid used this as his starting point.
 * Homer's most famous piece of Canon Fodder: The Fall of Troy. The Iliad closes with Hector's death and The Odyssey opens with Troy already fallen.
 * There were eight songs about the Trojan war... of which only two remain. The rest were lost even in antiquity, but everyone knew the general gist of the story (if not the specific verses).
 * In The Bible there are few descriptions of Jesus' life between his birth and his early thirties. Authors such as Anne Rice and Phillip Pullman have made novels filling in those gaps.
 * John 21:25 -- "And there are also many other things which Jesus did, the which, if they should be written every one, I suppose that even the world itself could not contain the books that should be written. Amen."
 * Maximum Ride frequently wanders off and leaves plot threads hanging—unfortunately, most of the fandom focuses on Fang/Max shipping and won't even touch the missing mad scientists, Max's past in the School, Jeb's true motives...
 * A Series of Unfortunate Events runs on this trope.
 * Animorphs has a lot of canon fodder at the end. The author, K. A. Applegate, says she actually likes endings better when loose ends aren't tied up. (Which certainly explains Remnants and Everworld.)
 * The Wheel of Time, according to Word of God, which is unsurprising considering how many plot threads are still dangling by book 12.
 * The Neverending Story (book version only) has this as a plot point: The reason Bastian Bux is special? Because everything he does creates plothooks for several more stories. Hence why he's able to save the fantasy land from dying: It's not because of the plot as such, it's because he sets everything in motion for it to expand forever, with every story opening up several more.
 * Gene Wolfe's Book of the New Sun intentionally made this into a major part of enjoying the book. He lays it all out in this quote: "My definition of good literature is that which can be read by an educated reader, and reread with increased pleasure."
 * Warrior Cats: What happened at the beginning of the clans? What happens to SkyClan next? How did several members of the Dark Forest get there? Who was Firestar's mom? Although the Erins are doing a pretty good job of tying things up recently.

Live-Action TV

 * The Sarah Connor Chronicles opened a couple threads in the first season mostly from when John was still attending high school - mysterious paintings around the school, mysterious behaviour from a girl John likes, something about said girl and Wichita, as well as a girl from Carlos's gang named Chola acting mysterious - all of which appear to be forgotten so far in the second season. (Chola does briefly appear in the second season, though there's no explanation of her earlier behavior.) A lot of these dropped threads were probably due to the writers' strike severely truncating the first season; that said, there are so many of them that season 2 almost qualifies as a minor Retool.
 * Plenty in Firefly:
 * What the government did to River, and whether others were subjected to the same treatment.
 * The Shepherd's past. (Revealed in a comic.)
 * Did Mal and Inara finally admit their feelings?
 * The fate of the Alliance, especially after the Miranda broadcast.
 * Did Niska ever get what he had coming to him?
 * According to a West Wing DVD commentary, Aaron Sorkin had some canon fodder forced on him by an actor that turned out to be a very good thing. When they were filming early episodes, Sorkin noticed that Richard Schiff was wearing a wedding ring during his scenes and objected that he didn't think the character, Toby, was married. Schiff agreed. Sorkin asked why the hell he was wearing the ring then, and Schiff said, "I'm waiting for you to tell me." As a result, a sad divorce was written into Toby's backstory, his ex-wife became a significant secondary character and the two of them got a story arc that was a favorite among fans and lasted well past the time Sorkin left the show.
 * Lost has some, though the writers have ended up using some intended Canon Fodder for themselves after setting it up.
 * Doctor Who - the end of Journey's End is pretty much just one huge open-ended fanfiction starter.
 * In the spin-off Eighth Doctor Adventures, there is a metric tonne of these with Fitz Kreiner. The writers seem to love leaving little hints about his backstory all over the books, and the Fandom extrapolates accordingly.
 * The Doctor lived for centuries before the series began. His time at the Time Lord Academy and the adventures he had before An Unearthly Child are favorite topics of Fanfic and Expanded Universe writers.
 * The Doctor's Opposite Gender Clone "daughter" Jenny steals a ship to wander the universe, much like her father.

Tabletop Games

 * Given the fact that much of its fluff is delivered through half-seen and heavily classified reports, Warhammer 40,000 does this a lot. One is "The Gates of C'Tan", which were mentioned in a 2nd edition race book and then later used as the name of an ancient star god two editions on.
 * In every Space Marine codex there's a list of the original twenty Space Marine legions, nine of which remained loyal during the Horus Heresy, and nine which turned traitor. But for legions II and XI, there is no information about their names or primarchs or homeworlds, only "All records expunged from library - order origination unknown." Games Workshop has said that they never intend to outright explain the mystery of the lost legions, since it gives fans something to work with. Indeed, even stories set during the Heresy will only hint at the legions' fate in the vaguest terms.

Theatre

 * This seems to be a big part of the Cats fandom. Such as follows:
 * What exactly is Demeter's past with Macavity?
 * Why did Grizabella leave the Jellicles?
 * What happened to Griddlebone during the seige of Growltiger's ship?
 * How come Mungojerrie and Rumpleteazer are mentioned as agent's of Macavity?
 * And, this is the big one: Who is exactly mated to whom?
 * It helps that all the chorus' cats don't seem to have a lot of personality despite being, well, cats. Yep, the fanficcers have a lot of fun with all of this.

Toys

 * This was and still is (though to a lesser degree) a major part of Bionicle' story. So much, in fact, that LEGO actively encouraged and held contests for the fans to write their own stories to expand on previously vague plot details, and the winner entries went canon. Author-written stories also do this, as mysteries that have been lingering around for years constantly get solved (in some cases, with very surprising results) as the story progresses. However there are still many things left unanswered, as several thousand year's worth of story has only been lightly touched upon, not to mention how many unexplored places, cities, islands, planets and universes there are. The fandom, of course, speculates the hell out of every tiny detail.

Video Games

 * Tetsuya Nomura (of Final Fantasy, Kingdom Hearts, and The World Ends With You fame) is sure to leave plenty of unanswered questions in his games, in case he can't make a sequel to answer them. Speculation is more fun, apparently.
 * Bungie Studios, creator of the Halo and Marathon franchises, absolutely relishes this; every game series and the canon surrounding it is festooned with little questions, hints, and unelaborated tangents, and Bungie's own attitude towards these questions is to let the fans come up with the answers.
 * Silent Hill. Holy crap, Silent Hill. While it is difficult to think ill of those that latch onto the smallest of details in a series that almost prides itself on providing as little information as possible without showing a blank screen, it becomes patently ridiculous at times. It also doesn't help that it is entirely probable the creators themselves know about as much of the series as the fans do, maybe less (see Sure Why Not and Shrug of God).
 * For the first game, the devs basically admitted to reaching into a big grab bag of Christian mythology, leading to many references that, when interpreted properly, make no sense. Silent Hill 2 averts this by being generally well thought out and dropping the Christian mythological motif altogether and focusing more on archetypical symbolism pertaining to the protagonist's own dark past and neuroses. The third game is an Author's Saving Throw for the first, more or less ironing out what you should care about and what you should discard from the first game and resolving dangling plot threads.
 * Touhou is chock full of those, especially the "The more devoted the fanbase, the smaller the detail that can become tempting Canon Fodder" premise; everything from a single sentence in a character profile to literal background details to simple Art Evolution accrues its own theories. Not helped by a lot of it being perfectly intentional, ZUN commonly sprinkling about unexplained details and being fond of the Shrug of God, most obviously with Sakuya's entry in Perfect Memento in Strict Sense, which outright says that no one knows anything about her past and offers some possibilities.
 * Whatever happened to Sherry Birkin after the events of Resident Evil 2? The last we heard about her is that she was under the surveillance of Wesker's agents after she was given to the government's custody. That poor kid's probably never getting off the damned bus.
 * We'll find out in Resident Evil 6.
 * Pick a background and/or psychological profile of Shepard's from Mass Effect and chances are, someone's done a fan fic about his/her life growing up. And outside of a few small sidequests in the first game related to said backstories, the details are left fairly vague enough so that fan fiction can thrive on this trope.
 * Super Robot Wars loves to play this trope with its ever-expanding Original Generation, and not just in the OG games themselves. Expect any given game to be littered with Sequel Hooks, prequel hooks, Alternate Continuity spinoff hooks, and many a Cryptic Background Reference. The big one right now is the "twelve keys" plot, which isn't limited to any one continuity and seems to be setting up for a crossover among crossovers.
 * Since Team Fortress 2 is building on what was once an Excuse Plot, many of the dangling threads have opportunities to become fanfic bait. How did the RED Spy meet BLU Scout's mom? When were the teams formed? How did Silas Mann become a Horseless Headless Horsemann?
 * What happened to Giovanni from Pokémon Red and Blue? A good portion of the fanbase seems to think, but it's hard to say. What happened to Pokémon Ruby and Sapphire's Archie and Maxie? Why is Red on a mountain; was he just passing by or has he been there for months?
 * The entire Zelda series. Games seldom make specific references to other games in the franchise, even when they're direct sequels, and despite every game supposedly taking place in the world, just at different times. Some examples: Where did Navi go? The window she went through turns out to be a dungeon in The Legend of Zelda Twilight Princess - is that where she was? Where does Link go after he saves Termina? Are the sages in TP the same ones from The Legend of Zelda Ocarina of Time? Did the sages die at the end of Ocarina? Who the hell is Kaepora Gaebora? Did the Deku Sprout from Ocarina become the tree in The Legend of Zelda the Wind Waker? If Tetra is an ancestor of the earlier Zelda, who was the father? Is Queen Rutela related to Princess Ruto? Does every game star a reincarnation of Link, or a descendant, or just an unrelated chosen person?
 * In The Sims series, the number 1 example of this is where is Bella Goth? Why was she last seen with Don Lothario? And why is there a townie named Bella Goth in Strangetown? This one is probably intentional. Other common ones include the mystery of the Tricou family and the House of Fallen Trees in the premade Downtown in Nightlife. Who are those mysterious Tricou townies who are all related? Why does Mrs. Crumplebottom hate everyone?
 * Beyond Good and Evil has Yoa, the mysterious, unknown-language-speaking, unusually blue orphan from the lighthouse. She has no real impact on the plot, outside of the fact that she is one of the orphans in Jade's care, but she's so different from every other NPC in the game that many people speculate on her true nature, and everyone seems to have their own guess.
 * The Portal series (and its interquel comic Lab Rat) has several areas often used as launching points, including life at Aperture and the events leading up to GLaDOS's takeover, the exact significance of 'Bring Your Daughter/Cat To Work Day', and the backstories behind several characters, including Doug Rattmann, Chell, Cave Johnson, and Caroline. And, of course, Chell's escape from Aperture at the end of Portal 1/2 (depending on when the fic was written.)
 * The Nasuverse is rife with this; despite having at least one Exposition Fairy in a single work, several events and concepts are often brought up in passing with little elaboration. Subsequent interviews and source books have managed to provide more information, but also end up unveiling new information that just raise further questions.
 * The Sonic series is absolutely rife with this. Other than Shadow, who had his entire backstory explored through the course of two games (ironically making the one character introduced as "mysterious" the one we know most about), and a few other exceptions (the Babylon Rogues, for one), anyone else's past is virtually a blank, including the title character himself. Perhaps the most glaring example of this is Knuckles, of whom we know close to nothing about, especially going by his status and his lack of any memory from before being alone on the island (Sonic Chronicles's canonicity notwithstanding).

Web Comics
"ZimmyXJack??? More like shutXup."
 * Tom Siddell, author of Gunnerkrigg Court, is well aware of the flimsy pretenses that inspire fans to start Shipping. He Lampshaded it on page 471: In the comic, Jack grabs Zimmy's arm because he's on the verge of freaking out, and Zimmy brushes him off. The Rant below simply reads:


 * Though it should be noted that later in the comic's run, Jack is revealed to have a crush on Zimmy.
 * Order of the Stick is still technically within the boundaries of this trope, much like Pluto is technically within the boundaries of the solar system.
 * However, it may be a bit of a stretch to call it "fodder" at this point, because the fans will speculate on anything, whether they're meant to or not.

Web Original

 * Red vs. Blue is absolutely packed with unanswered questions, that leads to loads of fan speculation. Creator Burnie Burns even commented that fans figured out entire plot twists and arcs before they are even aired. Almost everything is called back to at some point, but it can take multiple seasons to address issues, all the while raising new ones.

Western Animation

 * The Venture Bros is filled with stuff like this. With every episode comes a new conspiracy theory.
 * Avatar: The Last Airbender:
 * What happened to Zuko's mother?
 * Did Azula ? Word of God is deliberately silent on this.
 * Did Toph ever go home to her parents?
 * Is Appa the last air bison? Heck, did Aang and Katara become the Adam and Eve for a new race of Air Nomads? Fortunately, both are answered in the sequel series The Legend of Korra.
 * Chip 'n Dale Rescue Rangers has tons of it. Gadget's pre-"To the Rescue" life is as unknown as her father Geegaw's fate (let alone that of her mother) or what happened in Zanzibar back then, Tammy and Bink's mother has neither a name nor a husband, and so forth.
 * In Tale Spin, Kit's parents and Molly's father are never even mentioned. (Though seeing as how much of a bitch Rebecca can get, some fans think Molly's father most likely just left her.)
 * A couple of episodes of Transformers Generation 1 mentioned that many Transformers had fled Cybertron during the Civil War. In a late episode, Cyclonus and Scourge encounter a planet of them, and the main characters of Transformers Headmasters were all such refugees.
 * While a lot of stuff is explained through the official website and the Scientist's journal on Facebook, 9|Nine still runs on this trope like fossil fuel, mostly because there is very little insight into the other stitchpunks' lives before 9 made the scene.
 * Adventures of the Galaxy Rangers only ran one season, but left a luggage shuttle's worth for fans to play with 25 years on. How does Eliza get rescued (or does she get rescued)? What's Doc's backstory? All Mandell will say is that he's Jamaican, wealthy, and enlisted "reluctantly." What happened to Niko's home colony? Where are the Series 1-4 teams? What happened on Tarkon to create the Heart and the Scarecrow, and what's the reason for their rivalry? How many Supertroopers escaped the riot at Wolf Den? This is just the start; the series itself had Loads and Loads of Characters, plenty of Noodle Incidents mentioned in passing, huge amounts of Backstory that had to be compressed into a couple lines, and some stuff that had to fly too low for the casual fan and/or "target" demographic to notice.
 * Danny Phantom accumulated hordes of this, thanks to early cancellation and the head writer being replaced:
 * The entirety of "The Ultimate Enemy", from whether the Bad Future really was altered to the nature of Clockwork to the prospect of Dark Danny escaping.
 * Several things in "Reign Storm", such as the fate of Pariah Dark and the deal Vlad struck with Fright Knight.
 * The ending of "D-Stabilized",
 * There's a reason My Little Pony Friendship Is Magic acquired such a massive fanfiction community in such a short amount of time:
 * Equestria itself. How was nature altered to require pony assistance, and why has the Everfree forest remained resistant? (Or is it the other way around?) Is "Equestria" a planet like ours, or like the Discworld, or simply one nation? How do other sapient creatures like the dragons and griffins fit in? One very dedicated fan has even drawn an insanely detailed map of Equestria and the realms beyond it conceptualizing Equestria as one of many lands on a planet where magical quadrupeds are the dominant group of specis instead of bipeds.
 * The Royal Sisters. God Empresses or simply very powerful ponies? Caretakers or actual creators of Equestria? Appearing by themselves, or did their parents leave/die? What exactly happened to almost cause The Night That Never Ends 1000 years ago? And then the introduction of Discord in season 2 basically caused all the speculation to implode in on itself and then outward again into entirely new directions. This is further complicated by "Hearth's Warming Eve", where it is shown that they weren't around for the founding of Equestria, apparently appearing later.
 * Anything and everything to do with cutie marks and the degree of reliance the ponies have towards them, Cutie Mark Failure Insanity Syndrome in particular.
 * Daria had A Day at the Bizarro episode where an interdimensional wormhole behind a local Chinese restaraunt led to an island full of anthropomorphic holidays. While initially Fanon Discontinuity, nowadays many fans will use that wormhole for other sci-fi/fantasy stories where it can take them to a variety of other worlds.