* Various explanations for the inconsistencies of how time travel works between the three ''Franchise/{{Terminator}}'' {{movies}} are fanon. The ''Terminator'' movies (and the [[Series/TheSarahConnorChronicles TV show]], for example) never state how it works, just that it does.
* Given that [[WordOfGod George Lucas himself]] has said that the only things he considers "official" ''Star Wars'' are the films and the ''Clone Wars'' cartoons, it could be argued that the entirety of the ''StarWarsExpandedUniverse'' is nothing but Fanon. [[BrokenBase Some fans would argue with this point of view]].
** Wookieepedia, the ''StarWars'' Wiki, has a fairly complete [[http://starwars.wikia.com/wiki/List_of_fanon_elements_in_continuity list]] of fanon elements that found their way into the official continuity, either as an intentional homage or due to the authors mistaking them for canon.
** [[http://supershadow.com/ SuperShadow]], a website that deals almost exclusively in bizarre fanon notions, whose webmaster alleges that he is a close personal friend of George Lucas. [=SuperShadow=] is generally avoided by ''Star Wars'' fans, and discussing [=SuperShadow=] at all in a serious forum will get you slapped. [[PoesLaw Many of these people can't tell if [=SuperShadow=] is run by an idiot, or is just an elaborate prank played on a community that's already rife with ridiculous fanon ideas....]]
** A particularly irritating bit of fanon (covered in the blurb of [[http://www.darthsanddroids.net/episodes/0146.html this]] ''DarthsAndDroids'' strip) that many people still can't seem to understand is false is the idea that the "Balance of the Force" refers to the BalanceBetweenGoodAndEvil and was reached when Anakin killed all but two of the Jedi (Obi-wan and Yoda) leaving the number of Jedi and Sith equal. This is especially weird/frustrating when you consider how many people use the Jedi not thinking this would cause most of them to die out as "evidence" for them being stupid/corrupt and/or the prequel trilogy being an IdiotPlot. WordOfGod has stated that "Balance of the Force" means some Jedi, no Sith, and that the previous Jedi order didn't ''need'' to die. (And this line of thinking doesn't make much sense, either: an equal number of Jedi and Sith [unless that number was zero] wouldn't engender balance in anything and just cause an unending and highly escalated war.) As once was said, a lot of fans miss the idea that the Dark Side isn't Yin. It is Sin.
** There's also the idea that the midichlorians somehow create the Force. There's no indication of that in Canon, and according to Wookieepedia they are merely indicators of Force Sensitivity. There's even an in-universe theory establishing that the Force ''creates'' the midichlorians.
** The ExpandedUniverse is full of them. First we have the [[BrotherSisterIncest theory that Luke lost his virginity to Leia right after the Battle of Yavin]]. Then there's the [[FamilyRelationshipSwitcheroo theory that Anakin is really Ben's father]]. Sticking to Mara, another theory is about Palpatine's relationship with Mara. Slash fans vary from EveryoneIsBi to attitudes toward homosexuality are as restrictive in the GFFA as they are in Christianity, despite the fact that Jaina thought nothing of Goran and Medrit. And despite Lucas saying the Jedi have sex, the mischaracterization of them as celibate continues to this day[[note]]The celibacy thing, as explained in FanonDiscontinuity, is ignored due to Lucas saying they could have sex, but couldn't ''form attachments''. Think about that for a few seconds.[[/note]] Moving away from sex, most fans believe that Luke was under the DarkSide's influence in the Dark Nest Trilogy.
*** Regarding homosexuality in the GFFA, Bioware caught hell for [[HideYourLesbians Juhani]], whose article is still a mess from people arguing whether or not she was written as a lesbian. [[WordOfGod Stanley Woo]], her writer at Bioware said unequivocally that the answer is YES.
*** And then we get Karen "Canderous Ordo in Drag" Traviss who settled at least part of the issue by stating that the Mandalorians don't give a shit.
*** Male Exile. How many times was Wookieepedia edited for that one?
*** Ditto with so much as acknowledging Revan could be played as a female. Even the ''mention'' of it caused flame wars for a while. Give me a nickel every time some fanboy screams "Revan can't be a girl, it's CANON" and force me to pay a dime back every time someone says "Exile's a chick. It's CANON," and I'd still have enough money for a five-star supper and gas money.
*** We don't know what ''kriff'' means, just that it is used emphatically. It is assumed it means "to have sexual intercourse with".
** It is almost certain that the upcoming sequel trilogy will completely override all Expanded Universe material following ''ReturnOfTheJedi'', although whether fans will care is a different story. However, it will be a dark day for Wookieepedia, which will need to mark a vast portion of its articles as being non-canon.
** Many fans believe that Anakin didn't believe Palpatine's conspiracy theory about the Jedi trying take over the Rebublic; he only went along with it because Palpatine had something he needed. James Luceno even made this canon in the ExpandedUniverse. However there is nothing in the movie itself to indicate that Anakin ever believed otherwise.
* ''TheBigLebowski'': a popular theory among fans is that Donnie is in fact Walter's imaginary friend.
** Which doesn't make sense, because the Dude also acknowledges him a few times during the movie. Unless he is both Walter and the Dude's imaginary friend. But if he was, [[spoiler:why would they go to a funeral home after he dies?]] Unless that was a dream sequence... And so was [[spoiler:The cremation scene]]. The Stranger also refers to Donny, meaning he's also an imaginary friend. And who is bowling with them the whole time?
*** The Jesus also acknowledges Donny during the movie too.
*** As does Gary, the bartender at the bowling alley.
*** Essentially every character who appears in a scene with Donny acknowledges his presence in some way.
* ''Film/TheUsualSuspects'': There are a number of fan theories that identify Keyser Soze as any member of the cast you care to name. In the director's commentary, the filmmakers express puzzlement over this phenomenon, saying they felt the end is pretty clear.
* In TheFilmOfTheBook of ''[[ChroniclesOfNarnia Prince Caspian]]'', a geeky boy attempts to flirt with Susan at the train station in the first few minutes of the film. A small group of fans have grown attached to him, and christened him Warren.
* [[http://knowyourmeme.com/memes/figwit Figwit]] the sexy elf from ''The Fellowship of the Ring'' was noticed by fangirls and anyone else who got bored during the Council of Elrond scene; he was adopted by the fandom and given his name, and when he reappeared in [=RotK=], there was much squealing and choking on popcorn. Incidentally, he's played by Bret [=McKenzie=] of FlightOfTheConchords.
** Figwit seems almost to have been embraced by the creators; Bret [=McKenzie=]'s character returns in ''Film/TheHobbit'' trilogy, as Elrond's personal herald, no less, with the name "Lindir" (which means "singer.")
* ''Film/EventHorizon'' is said by some fans to be set in the ''TabletopGame/{{Warhammer 40000}}'' universe.
** Ditto for ''Film/TheChroniclesOfRiddick''. It IS extremely easy and quite possible to argue that it takes place sometime in the Dark Age of Technology. In fact, the events of the film line up quite perfectly with much or all that is known about the Warp. While the film makers may or may not have intended it, it is in fact perfectly reasonable to say that ''Film/EventHorizon'' is the first ever [=WH40K=] movie.
* ''Film/FightClub''
** A surprisingly large number of people sincerely believe that the name of Edward Norton's character is Jack. In fact - and this is [[LampshadeHanging lampshaded]] in the film - his true name is [[spoiler: never revealed, although an argument can be made that it is, in fact, Tyler Durden.]] Notably, the novel is a bit more unambiguous about the last point, as it includes a brief scene after TheReveal where the Narrator [[spoiler: shows his driver's license to Marla to prove that "Tyler Durden" isn't his real name]].
** In the script and behind the scenes they ''did'' use the name Jack, though [[spoiler:as an allusion to the Reader's Digest articles written by an organ in first person discussed in the film]].
** Another popular theory is that ''CalvinAndHobbes'' is the prequel to Fight Club, with the Narrator being an older Calvin, Marla as Susie, Bob being an older Moe trying to be TheAtoner and [[spoiler:Tyler as a vengeful reincarnation of Hobbes.]]
* The fandom for ''Film/{{Inception}}'' has unanimously decided that Eames' totem is a poker chip. This is fleetingly implied in the film but never explicitly stated.
* Michael Myers, the antagonist of ''Franchise/{{Halloween}}'' [[spoiler: never dies in either of the two original timelines, presumably surviving the end of both ''Film/HalloweenTheCurseOfMichaelMyers'' and ''Film/HalloweenResurrection'', the last in each respective timeline. And with the start of [[Film/{{Halloween 2007}} a remake]], it is clear neither timeline is going to be "ended" by the film makers. So, Chris .R. Notarile created a fan film (with professional voice actor Creator/TomKane in it) depicting the death of Michael Myers at age 60, from the rage inside him (as Dr. Loomis predicted in ''Film/Halloween5TheRevengeOfMichaelMyers''). It could fit into either timeline.]]
** Another of his fan films depicts [[Franchise/ANightmareOnElmStreet Freddy Krueger]] [[spoiler: Being captured by Pinhead sometime after his death in ''Film/FreddyVsJason'', and torn apart by Jason Voorhees, (the mind of) Michael Myers, and (the presumably-deceased soul of) [[Franchise/TheTexasChainsawMassacre Leatherface]], with Pinhead stating "Your reign of evil is now over.", indicating that he will never return again.]] This contradicts ''Comicbook/FreddyVsJasonVsAsh'' and its sequel, but these are an alternate sequel to ''Freddy vs. Jason'' than ''Film/JasonX'', which couldn't take place after ''Freddy vs. Jason vs. Ash 2: Nightmare Warriors'' because [[spoiler: history is altered to prevent Freddy's transformation into a dream demon, thereby preventing him from resurrecting Jason at the end of ''Film/JasonGoesToHellTheFinalFriday''.]]
* In TheBoondockSaints fanon, it's generally agreed that Connor is the older twin.
* HighSchoolMusical fic
** If Chad is not dating Taylor, he's dating Ryan 99% of the time. Probably has something to do with the [[HoYay sexy baseball scene]] in the second movie...
*** Even fans who don't ship Ryan/Chad assume ''something'' went down in the locker room after that baseball game, not helped by the fact that they're [[SexyShirtSwitch wearing each other's clothes]] in the next scene.
** Sharpay often has a cutesy nickname that her mother calls her by, to go with Ryan's "Ducky".
* Sarah's stepmother in Film/{{Labyrinth}} is usually referred to as either "Karen" or "Irene". No one seems to know for sure what her actual name is.
** The official movie novelization establishes her as Irene, though Karen remains more popular among fans.
** Labyrinth has a very active fandom, especially fanfiction and fanart, and most of it draws upon the same fanon:
*** Sarah's last name is Williams (it's mentioned in the film novelization, but not in the movie itself)
*** Jareth is Fae. He's only ever referred to as the Goblin King in the movie, but his behavior and BlueAndOrangeMorality lead a lot of fans to believe that he's part of a larger society of faeries.
*** The Goblin Kingdom, and the Labyrinth, are located in a magical world called the Underground (drawing from David Bowie's song of the same name, featured in the opening and closing credits of the film). Whether or not it's ''actually'' below our Earth is debatable.
*** Sarah goes to college to study English or theatre.
*** Jareth and Sarah reunite when she's in her twenties, and they have a torrid romance and get married.
*** Jareth and Sarah have some kind of psychic or magical connection, so that they can sense when the other is in danger.
*** Toby has no memory of the events of the film. (Realistic, since he was a baby, but not necessarily true.)
*** Jareth's mother is Jadis, the White Witch. (Popularized by Pika-la-Cynique's multifandom comic Girls Next Door)
* It's a popular theory among Quentin Tarantino fans that at least some of the events of ''Film/PulpFiction'' occur on the same day as the bank heist in ''Film/ReservoirDogs''; in particular, the fact that no cops are around to stop Jules and Vincent while they're driving a car covered in blood in the middle of a busy street during broad daylight is because they're occupied with the heist and its disastrous aftermath.
** Alternately, many fans have proposed the theory that ''Film/PulpFiction'' is a direct sequel to ''Film/ReservoirDogs'', and that the [[{{Macguffin}} mysterious briefcase]] in ''Pulp Fiction'' contains the diamonds from the heist in ''Reservoir Dogs''. This has some basis in fact, as WordOfGod has confirmed that the briefcase was supposed to contain diamonds in the original draft of the script.
** The theory that ''Film/KillBill'' is [[ShowWithinAShow an action movie that Mia Wallace starred in during her time as an actress]]--possibly even a reworked version of her failed ''Fox Force Five'' TV pilot--has recently caught on with Tarantino fans.
* Many viewers of ''Film/{{Avatar}}'' believe [[spoiler:Eywa is manipulating ''both'' sides of the conflict to achieve her ends of getting rid of the RDA. This is based on absolutely no canonical evidence whatsoever. She doesn't even visibly interfere until Jake takes some time to explain the situation to her, and the Na'vi are about to ''lose'' their decisive battle, when she could've just ZergRush'd the RDA at about any time.]]
* Even though it takes place in an alternate timeline, it is generally accepted among fans of the 2009 film ''Film/StarTrek'' that Kirk was sent to Tarsus IV after the "car incident", and was present for the massacre on the colony just as the Kirk of the "main" ''Franchise/StarTrek'' timeline was. It's not unusual for this to be a profound influence on his character in fic. The notion has also crept in that nu!Kirk studied under [[Series/StarTrekEnterprise Hoshi Sato]], who was said to be on Tarsus IV at the time of the massacre.
** Also, the vast majority of reboot fanfic writers write Kirk's stepfather as an alcoholic, ultra-abusive, evil child molester and his mother as depressed and emotionally distant.
** And after the scene in the 2009 film with Kirk have strange reactions to everything that Bones injected him with, it has been decided by the fans that Kirk is essentially allergic to a large percentage of medications.
* [[Film/TheBourneSeries The Bourne Legacy]] is [[Film/TheAvengers Hawkeye's]] origin story.
* ''Film/TheAvengers'' has this site, [[http://theavengersheadcanons.tumblr.com/ Avengers Headcanons]], that is dedicated to this trope.
** Connected to the above, popular theories arise concerning Hawkeye's backstory, many inspired by the mainstream comics. The most common are Clint was a CircusBrat and/or has a criminal record (which again, is basically his comics backstory), formerly served in the US Army or in some kind of Law Enforcement division, is a single father with a young child, is dating/married or was formerly dating/married to [[ComicBook/{{Mockingbird}} Bobbi Morse]], that Bobbi Morse is the mother of the aforementioned child, and many more.
* ''PlanetOfTheApes'': It's accepted by many that Zira and Cornelius coming to the past and Caesar's birth there altered the 'verse's history, greatly speeding up the ape revolution and making it happen much earlier than the one that led to the events of the first film.
** And on a connected note, the aftermath of "Battle" is often seen as being different than the original timeline, meaning the world might or might not have been destroyed as it was in 'Beneath' but no one knows for sure.
** If the closed loop theory is held, there's wide speculation that anger at Caesar led to him being erased from ape history later on, leading to the scrolls Zira and Cornelius read having Aldo as the first to say "no".
* A common theory regarding the ContinuitySnarl between ''Film/XMenFirstClass'' and ''Film/XMenTheLastStand'' is that the Xavier who visited Jean Grey was, in fact, a psychic projection.