A single-author example is Golgo 13; Taiko Saito prefers to keep his past a mystery, so there are several different histories for him.
The end result of ZigzaggingTomato in the Mirror in The Big O. Roger was either born after the Event in Paradigm, but thanks to his burst of Memory, is revealed to be a cop (or a major in the army) from before the Event who quit once the first Megadeus was discovered underground and became Big O's pilot at some point, but then, after a final burst of memory, it's revealed that he might actually a robot mass produced to pilot Big O units. It's made even more confusing when you realize that none of the memories from before the Event actually existed, and Paradigm City was a virtual reality, one which looks suspiciously like New York City. Good luck trying to sort out that mess...
Hiruma from Eyeshield 21 is seen pulling this during a flashback chapter. Is his father a shogi player, a doctor, or a white-collar criminal? Apparently, it depends on what he feels like today.
Eventually it is revealed he was an amateur chess champion.
To keep the revelations nice and fresh the manga and video game adaptions of Code Geass seem to have this, especially in regards to CC and Marianne.
A Team Rocket-themed episode of Pokémon Chronicles implied that Jessie and James didn't know each other before joining Team Rocket, but an early episode implied they knew each other fairly long before that.
Hell, Team Rocket is full of these. Did Jessie go to nursing school or did she join a bike gang? Did Jessie and James meet in the bike gang, at an academy they flunked out of, or when they joined Team Rocket? Was Meowth Giovanni's right-hand 'mon until Persian came around, or was he a servant?
Kai Hiwatari from Beyblade. It even creates confusion about his nationality.
One episode of Slayers Next has a chef who gives 4 different versions of his orgin, one for each of the main characters. It is then subverted at the end when all four back stories turn out to be true.
Excalibur in Soul Eater has a habit of telling long and rambling stories about himself with details that change as he's telling it. "It was the same day as today, Tuesday, or was it Wednesday, no I'm sure it was Monday. Anyways it was a fine Sunday and..."
King Mob from The Invisibles has a self-constructed multiple choice past, whose point is to stop enemies with telepathic powers from prying information about him and his group. If they try, they can't be sure which memories are true and which are part of a fake past.
Wolverine, of the X-Men, was especially susceptible to this; his amnesia about his past was a common plot driver in early-90s stories, and what we knew kept getting retconned. Even after it was made so that he could remember every single thing that ever happened to him, the series Wolverine: Origins is still trying to milk the concept.
Wolverine's arch-enemy Sabretooth likewise has multiple possible pasts. He was part of the same "Weapon X" program as Wolverine, which included false memory implants, so that's no surprise.
The DCU's Crisis Crossovers (and not just the ones actually bearing the Crisis name) altered reality, changing the pasts and presents of a variety of characters. Legion of Super-Heroes has had three such reality reboots (counting the original Crisis.) Also, retellings of characters' origins will vastly alter them on occasion, with no Crisis-type justification. As such, most DC characters with a significant amount of history have multiple formerly-canonical histories, as well as ones that are equally canonical but completely incompatible.
Superman, for example, has a canonical multiple-choice past: he was given the choice between two of his innumerable origin stories, and he picked the one that he liked more (and, incidentally, made more sense).
Also played with in one issue of Robin, which starts off with a flashback about a green-haired, white-skinned boy in a purple shirt with a pony. "Or was it a bike?" the narration muses. "No, a pony." The little boy did something bad, and then his daddy shot the pony in front of him. Cut to the Joker, narrating, and he's actually weeping real tears. He's in a cell at Arkham, and a speaker on the wall asks him if the story is true, because it's the seventhFreudian Excuse story he's told them.
Harley Quinn: Joker told me things, secret things he never told anyone... Batman: What did he tell you, Harley? Was it the line about the abusive father, or the one about the alcoholic mom? Of course, the runaway orphan story is particularly moving, too. He's gained a lot of sympathy with that one. What was it he told that one parole officer? Oh, yes... 'There was only one time I ever saw dad really happy. He took me to the ice show when I was seven...' Harley:(crying) Circus... He told me it was the circus. Batman: He's got a million of them, Harley.
A 2004 story arc in Batman: Gotham Knights suggested that the Killing Joke version is more or less Joker's real past, since a pre-Riddler Edward Nigma witnessed the murder of "Jack"'s wife and later offered to tell the Joker who did it (although the version told in The Killing Joke has it that his wife was killed in an accident, not murdered). Later writers have pretty much ignored it.
In the 80s, an issue of The Question reinvented The Riddler; his real name was Edward Nashton, and he changed it to Edward Nygma when he became the Riddler. His obsession with riddles wasn't born from cheating in a school competition and wanting to prove how clever he was; it was a compulsion to tell the truth due to a violent father. It also claimed that he was never a major Batman villain. Later, Neil Gaiman wrote a Secret Origins story in which Riddler retells his classic origin, before adding "Or maybe I'm a frustrated second-rater called Nashton with a meaningless schtick!"
The Scarecrow's first origin story begins with him frightening birds as a child. Skip forward a few decades to the Year One version, and in a 180 turn he's frightened by birds — namely, by a trained attack squad of crows in the old chapel his great-grandmother likes to lock him in. Also, origin stories differ as to whether he was a child bully (i.e. his first episode in the animated series, which had a flashback of him chasing girls with handfuls of snakes) or a bullied child.
Deadpool of Marvel Comics also has a large number of competing origins for his past. There's also some disagreement as to whether Wade Wilson is his real name or a name he stole from someone else. Pretty much the only thing all the origin stories have in common is that his regeneration abilities are a result of time spent as a Weapon X test subject. Like the Joker, Deadpool is insane enough that he probably has no idea himself which one is correct. He does seem fairly certain that Wade Wilson is his real name, however.
Somewhat ambiguous whether or not he really has an actual Multiple Choice Past or not. The only person that ever brought up the possibility does so during a Mind Screw.
T-Ray even hints that 'Pool may not be Wade Wilson at all - instead, T-Ray himself would be Wade Wilson, and Deadpool stole the name from him. The comics seem to keep disproving this story, but given how nuts DP is and in light of what's been exposed in this bullet point, the jury's still out.
Cable and Deadpool stated that Wade's father was an abusive military officer who was shot and killed by one of Wade's friends, while a later run seemed to imply that has father had walked out on him as a child, and started a new family elsewhere.
The Marvel NOW! run eventually clarifies Deadpool's origin, as well as the various Plot Holes and retcons. It turns out the stuff with T-Ray being the real Wade, as well as all the conflicting stuff about his family, were the result of a scientist named Butler putting Deadpool in advanced hallucinations while he harvested his DNA over the years.
In Supreme Power, Zarda gives three conflicting origin stories that involve both her and Hyperion when he asks her where she came from. Since Zarda's demonstrably insane, it's safe to say none of them are even close to true.
In the original Teenage Mutant Ninja Turtles comics (and later, the movies and the '00s cartoon), Splinter was originally the beloved pet rat of Hamato Yoshi, who saw his master's assassination and then later was mutated into a humanoid intelligent rat-being. In the '80s cartoon series and the spinoff comic books, Splinter is Hamato Yoshi himself, forced into exile and living in the sewer when he first encountered the mutagen. Having recently been in contact with sewer rats, the mutagen turned him into a humanoid rat. In his profile on the DVD of the first live-action movie, it's said that Splinter's origins are "shrouded in mystery" and that either one of them is possible.
One issue of Secret Origins gave four different, mutually-exclusive origins for the mysterious Phantom Stranger. According to the Word of God, they're all true.
When a Black Lantern tried to eat the Phantom Stranger's heart during Blackest Night, it saw three of those backstories, leaving it stunned long enough for the Stranger to spring a trap. The Stranger's response? "You have seen everything and you have seen nothing."
Additionally, all of these stories were parodies of Marvel characters' origins.
Bizarro, although in this case it's a Justified Trope because, technically, Superman has been cloned more than once, and not always perfectly, and more than one of those imperfect clones have been named Bizarro.
Power Girl has a particularly interesting multiple choice past. Originally, she was Supergirl's equivalent from Earth-2. After Crisis on Infinite Earthsretconned all the alternate Earths out of existence, Power Girl was kept around, but now lacked an origin or even a defined species, as Superman was now the only Kryptonian around. Over the years, different writers tried different takes, giving her a magical Atlantean past, an alien Daxamite heritage, and so on. With the return of the multiverse in Infinite Crisis, Power Girl's history has now become her origin: she was from Earth-2, but after it ceased to exist the universe spent years trying to make her fit, but her true Kryptonian heritage has now been re-established.
Post Crisis Supergirl also had this in spades... when she first appeared her backstory was simple, She was sent to Earth at the same time as Superman and was his older cousin and she was supposed to look after him when they got there, but she was trapped in Kryptonite and in suspended animation for years and didn't emerge until Superman was a full grown adult. But then it was revealed that, that origin might be partly false and that her whole side of the El family was evil and she was sent to kill her cousin. But then it was revealed that, while she was sent to kill Kal-El it's because there was a curse he inherited that would break down the barrier to the Phantom Zone which Jor-El, Superman's Father, invented (this too would later be ignored) and that eventually phantom zone monsters would start crossing over to the real world unless Kal-El was killed; this origin was even verified has being correct by a Monitor... but then Supergirl's parents showed up and it turned out that her real origin was a modified version of her Silver Age origin (that a chunk of Krypton survived the destruction), and that everything else was the affects of Kryptonite poisoning making Supergirl crazy.
Donna Troy's past is so complicated, writers are more likely to spend more time attempting to clean it up rather than chronicling her current adventures. To sum it up as briefly as possible:
After she spent the first 21 issues of the original Teen Titans series with no backstory, Marv Wolfman would establish that she was an orphan rescued from a burning apartment building by Wonder Woman. He would later expand upon the story in New Teen Titans, revealing that the couple that died weren't Donna's biological parents and that her mother had died after giving her up for adoption.
After the Crisis on Infinite Earths rewrote continuity, Wonder Woman became a newcomer to the DC Universe. Since this meant Donna would predate her as a superhero, Wolfman and Perez then revised Donna's backstory to state that she was rescued by the Titans of Myth and sent back to Earth at the age 13 (with her memories wiped). She would then base her Wonder Girl costume off of the American flag.
In the late '90s, John Byrne decided to apply his own retcon: Donna was actually a magical twin of Diana, created from a mirror and kidnapped by Dark Angel, who would then curse her to live multiple lives of tragedy. Byrne would also reveal that Donna based her "Wonder Girl" identity off of Hippolyte's Golden Age stint as Wonder Woman (via a time-traveling paradox).
Allan Heinberg would finally use the mirror origin in stating that she was "born of magic", but would add that Wonder Woman rescued her and that the Amazons and Titans of Myth trained her.
In his first appearance, Booster Gold villain Black Beetle claimed to be the Blue Beetle of the 27th century. When revealed as a villain, he claimed to be Jaime Reyes' greatest enemy, who blamed Jaime for a death (and the final issue of Blue Beetle would strongly hint as to who he was) making him from the very near future. In a later appearance, Booster calls him "The Black Beetle, direct from the 22nd century. Or the 27th." to which the Beetle replies, "Or 15th. Whatever I choose to say for the sake of misdirection". Later, he had his first (from Jaime's point of view) encounter with Blue Beetle, in which he initially claimed to be the character the Blue Beetle story hinted at, before saying he wasn't; he killed that character. He follows this up by claiming to be Jaime himself.
Marvel Comics' Hell Lords have one mutual origin, but most also have their own versions. It doesn't help that they are demons, so everything they say can be a lie and each story has set arguments and events that either supports or deny it.
The mutual story connects them to the Elder Gods, the first generation of Earth gods. When evil god Set found out that he could steal the power of other gods by killing them, he caused the first war between gods. Gaea gave birth to Atum, who promised to destroy all evil gods. But their evil energy corrupted him, and he turned into the monstrous Demogorge, the God-Eater. Demogorge killed all gods who didn't escape to another dimension. Then he released all power he couldn't contain. This power has been consciously or unconsciously shaped by young humanity into the form of their fears, creating Hell-Lords, the first demons.
Mephisto told his own version during Infinity Gauntlet crossover - in his version an abstract-equal being called Nemesis was lonely, so she created companions from her own essence, but forgot to give them good nature. When they all turned evil, she destroyed them and committed suicide. But her creations have somehow been reborn and become the first demons in the Universe. Mephisto claims to be one of them.
Marduk Kurios claims to be both the real Satan and Babylonian god Marduk, who has degenerated into a demon, after he found that he could gain much more power from human souls than their belief.
Lucifer has his classic biblical origin of the Fallen Angel and denies any connection between him and other Hell Lords, but he's not different from them at all.
Bullseye he has multiple tales about his past life, he is either a CIA agent, a baseball star...he makes up so many stories that no one knows who he really is.
Chthon has also claimed to be the first Demon.
Runaways: Did Chase kill someone because of/with his van? Even he's not sure—he later admits that he made up stories to attempt to justify his father's abuse of him. At one point, he seems extremely certain he didn't; later on, he seems totally certain that he did.
Nico: You've told a few different versions of that story. Chase: Right, well, in this one...
Arcade, the theme park-themed Professional Killer who has menaced Spider-man and the X-Men on numerous occasions, has told a number of different versions of his origin story, although they all involve him murdering his rich dad for his money. Since Arcade's real name is unknown, it could all be lies.
And the trope is played absolutely literally in Vertigo Comics' The Unwritten, where the origin of Lizzie Hexam is structured like a Choose Your Own Adventure comic: Is Lizzie Hexam actually a character who emerged from out of a Dickens novel, is she a victim of child abuse who gave up her body to a fictional construct, or simply a delusional girl? Did Wilson Taylor treat her like a daughter, like a prisoner, or like a science experiment?
Interestingly, while the reader can choose multiple paths for Lizzie, they all end with her at the press conference from issue #1. The subtext of this meshes very closely with Tom's words to Lizzie in the hospital: which story you decide to follow is more important than which one is true.
King Shark was introduced in Karl Kesel's Superboy as possibly the son of a Hawaiian shark-god and a mortal woman. Later in the same run, Kesel introduced circumstantial evidence suggesting he was actually one of the mutated animals from the Wild Lands. Later still, Kesel's run on Aquaman confirmed the shark-god story.
Heavily used in regards to The Sentry, especially the relationship between him, his civilian identity Robert Reynolds and his Superpowered Evil Side the Void: is the Void the result of a "mind virus" implanted by Mastermind? Are Sentry and the Void the good and evil nature that exist in every person given form by the serum Reynolds took? Is the Void a Split Personality formed by Reynolds repression of his past as a thief and junkie? Or is the Void Reynolds' real personality and the Sentry is the fake one? All of these were presented as equally likely. Which is pretty appropriate since Sentry is quite crazy. In fact, given that Sentry is crazy and is a Reality Warper, it's strongly suggested that the "true" version is whatever he believes at the time.
The Time Trapper from the Legion of Super-Heroes, who at various points has been a Controller, a future version of his/her own sidekick, a future version of Cosmic Boy, a future version of Lori Morning, and a future version of Superboy-Prime. Following that last revelation, Brainiac 5 hypothesised that the Trapper is the Anthropomorphic Personification of failed timelines, and exactly what history leads to someone at the End of Time wearing a purple cloak and fighting the Legion changes every time the Trapper does anything.
Teddy "Red" Herring of Red Herring is said to have an obviously false right eye (though the art depicts it identically to his left), and always has a different explanation for it: a childhood accident, shrapnel from a grenade in Iraq, a flesh-eating virus, the heel of a jealous ex-girlfriend... In all likelihood, none of these are true.
Played with in Batman: Joker's Daughter; the Joker's Daughter has three entirely incompatable origins which she relives when the Anchorite uses her power on her. The twist is not only are none of them true, but her big secret (that she can't even admit to herself) is she never had an origin; she was living a life that was entirely unremarkable in every way, and just decided she wanted to be the Joker's Daughter.
Tangent Comicsversion of Green Lantern (a mystic woman who carries an Asian lantern able to temporarily ressurect the dead), tells three different versions of her origin.
In both versions of Funny Games, the dominant killer gives several accounts of the other's backstory, one after another. Ultimately, their origins are never resolved. They exist simply to be characters in the film.
The Kid Stays In The Picture opens with the following quote:
"There are three sides to every story: my side, your side and the truth. And no one is lying. Memories shared serve each one differently."
In Phone Booth, the sniper hints at his own past on at least two different occasions, then writes them off again (mocking Stu while he does it) inside of a minute.
Spacegodzilla was either created by Godzilla's DNA from Biollante being sucked into a black hole after she (Biollante, not Godzilla) went into spore-form and drifted into outer space, OR when Godzilla's cells that somehow got onto Mothra were carried into outer space by said giant moth and were pulled into a black hole. And, depending on if you count the toys, the DNA may or may not have fused with a crystalline alien creature after falling through the black hole.
Similarly, there's Godzilla's Alternate Company EquivalentGamera. Is he an ordinary turtle mutated by pollution? A cyborg planetary defense weapon created by a lost civilization? A prehistoric reptile that inspired Xuanwu the turtle god from Chinese mythology? An actual turtle god?
Even in the films where Gamera's backstory about being an Atlantean cyborg is consistent, his Arch-Enemy Gyaos, whom the Atlanteans created Gamera to fight gets it even worse. He's either another Atlantean creation that turned against them, or part of a race of aliens that plan to devour the Earth. Or both.
In the film adaptation of Battle Royale, Shougo claims his dad is a doctor, a cook, and a boat pilot at various points in the movie to explain whatever useful skill he's displaying at the moment.
He also lost a body part in each of these conflicts.
Chef Horst in Ratatouille has served a prison sentence, but nobody knows why because every time someone asks, he gives a different explanation ("I robbed the second-largest bank in France using only a ballpoint pen."), none plausible ("I created a hole in the ozone over Avignon.") and probably none true either ("I killed a man. With this thumb"). The thumb story comes back when he scares off former-Chef Skinner with it... with Skinner somehow being thrown out of the kitchen. There might be some truth in that one.
An early examples comes from Two Lane Blacktop: the unnamed driver in the GTO gives a number of conflicting stories about his past. It's clear that they're all lies because his last story conflicts with information we see in the film.
Princess Ozma of the Land of Oz series had retcons even within the books written by Baum himself. Originally the human daughter of Pastoria, she was also of the fairy lineage of Lurline.
H.P. Lovecraft's Cthulhu Mythos has details that differ from story to story. Part of this is because several authors contributed to the Mythos and they sometimes had quite different views, but even the stories written by Lovecraft himself are not always consistent. For example, it is not clear if Mt. Kadath and the plateau of Leng exist in the real world (their only actual appearance is in the Dreamland stories, but they're mentioned as real world locations in other stories) or whether Cthulhu himself is a Great Old One or not (in Call of Cthulhu he's mentioned to be one of Them, in The Dunwich Horror he's referred as Their "cousin"). This is likely because H.P. Lovecraft didn't give a damn about canon and frequently recycled names and concepts, but varied the details depending upon the particular story.
Lucien of Character Issues continuously claims that his father died in a variety of ways, ranging from crushed by a TV to poisoned by an Elf-like creature which snuck into his house at midnight every night. Depending on the view point, this is either hilarious or horrific.
In The Light Fantastic, the universe itself has a Multiple Choice Past; the Eight Great Spells of the Creator claim to remember the creation of the universe, but they all remember it differently. Fridge Brilliance when Eric reveals the Creator wasn't really involved in the creation of the universe, just of the Disc itself, so his spells wouldn't remember it directly.
An additional universe-creation explanation was given in Soul Music.
A mystery novella serialized by the San Diego Union-Tribune newspaper during The Nineties, wherein the Big Bad offered up a different explanation for the huge scar across his face in every installment. In the final chapter, it's revealed that the wound was merely the result of a nasty fall at a grocery store.
Likewise, Hawk from the Hawk & Fisher novels tells people all kinds of improbable stories for how he lost his eye, such as he pawned it or lost it in a card game. In fact, he got clawed in the face by a demon in Blue Moon Rising, back when he still went by his given name as Prince Rupert of the Forest Kingdom.
And Campbell in My Sister's Keeper tells us various different stories about why he has his service dog, until at the end it's revealed that The dog can detect when he's about to have a seizure.
Peter Pan in the original Peter Pan book by J.M. Barrie. He tells Wendy of how after being adopted into Neverland, he tried to return home to his parents only to find the window locked and another little boy in his room, and he uses this as his justification for disliking adults. The narration of the book says something along the lines of "this may or may not be what happened; but it's how Peter remembered it at the time and thus he wholeheartedly believed it."
Also there are a few inconsistencies between his origin story in 'Peter Pan in Kensington Gardens' and that in 'Peter and Wendy'.
An odd case is the main character of This Immortal by Roger Zelazny, who time and again tells some different story about himself. The novel opens with Conrad/Konstatin's new wife finding out he's not twenty-something like she is, he's around eighty. Then other characters wonder if he's somehow connected to other Greeks named Konstantin, each with one brown eye and one blue eye, who happen to be even older, one of whom was a world-famous terrorist. Then more characters come into the story, and they have their own stories about his past. He's hundreds of years old, has never physically aged past 23, and he was every one of these people.
Either confusing pasts is a theme with Zelazny, or he just has trouble making up his mind when he's writing a story: the Chronicles of Amber involves dozens of "histories" for Corwin, and he spends much of the series trying to unravel which ones are true. (Adding to the confusion: Corwin is immortal, he can travel to as many worlds as he wants, there are "shadows" of him in a lot of those worlds, and he has about 15 siblings with similar powers who all lie and scheme and plot.)
Zelazny's Lord of Light mentions a woman who was Sam's "mother or daughter or wife, or perhaps all three," which seems tricky even with reincarnation.
In The Thirteenth Tale, one of the main characters is an author who tells a different life story every time she's interviewed. It's implied that she has difficulty breaking this habit, even when she starts out with the intention of telling the truth.
J. R. R. Tolkien never managed to come up with a satisfactory backstory for the Orcs; he had created them so his bad guys had some Always Chaotic Evil mooks, but this clashed with his Catholic beliefs that no free willed being could be pure evil. Origins for the Orcs include: corrupted Elves (featured in the published Silmarillion), corrupted Men (although this doesn't fit the timeline), intelligent animals or simply primitive tribes.
Also true of Galadriel and Celeborn—Unfinished Tales gives multiple drafts of their history that Tolkien wrote, with no clear chronology to tell us which version is the latest (and presumably most authoritative, though some version cause other continuity problems) and with more notes that suggest Tolkien was planning on revising it again before the publication of The Silmarillion. We don’t even know whether Celeborn was a Sindarin or Telerin elf, or whether Galadriel was actually part of Fëanor’s rebellion or just went along because she wanted to carve out her own kingdom in Middle-Earth. And those are some pretty major differences.
Often repeated is some variant of: "Of this matter two things are said, the truth of which is known only to the Wise Ones who are gone . . . ."
In Dukaj's "Ice" the main character (and pretty much everyone else) seems subject to this. It's actually used as a resurrection technique to revive Nicola Tesla!
In the Eighth Doctor Adventures novel Sometime Never one of the Council of Eight, a group of antagonistic beings who resemble the eight Doctors, absorbs the Doctor's personality and flees in a timeship with the Doctor's granddaughter Zezanne. If you take the view (popular at the time but thouroughly contradicted later) that Gallifrey is Ret Gone, this provides an alternate origin for the First Doctor and Susan.
Various authors have taken up the stories of Conan the Cimmerian since Robert E. Howard died. ("Barbarian" is a movie thing.) Some, such as Robert Jordan, have tried to remain consistent to the relatively vague timeline; others... not so much.
Philbrick, the shifty butler in Evelyn Waugh's Decline and Fall, gives a different version of his backstory to everyone who inquires. When the other characters confront him after comparing notes, he admits that he lied but adds that they'll never find out the truth.
A mild case: Lord Emsworth, of P.G.Wodehouse's Blandings, acquires another otherwise unmentioned sister in nearly every story. (He consistently has just one brother, though.)
Live Action TV
In Smallville, Moira Sullivan, mother of Chloe Sullivan, has a past which varies slightly every time in her few appearances, the difference usually including the time when she left Chloe.
Doctor Bashir on Star Trek: Deep Space Nine had about five different stories explaining how he first realized he wanted to be a doctor as a child. This was later explained as a result of him trying to hide his actual origin story - he received illegal genetic enhancements as a child.
Garak also had a Multiple Choice Past. The second-season episode "The Wire" had him confess to different, contradictory stories about why he's on the station, and other people offer contradictory information about what they knew of his past. At the end, Bashir confronts him about it, only to have Garak declare that they were all true.
Bashir: Even the lies? Garak:Especially the lies.
The non-canon book A Stitch in Time has Garak remember his childhood and the real reason he was exiled, while walking through the ruins of Cardassia. He killed a high-level official, who caught Garak with his wife (all three went to school together). Interestingly, his boss and father Enabran Tain actually ordered the assassination, but it was the semi-public way Garak did it that got him kicked out of the Obsidian Order.
The Janitor from Scrubs has given many contradictory tales of his past, from massively different stories about his tortured childhood, to forgetting whether he went to Harvard or Yale. It's implied he does this largely to mess with J.D.
He is, however, a world-class track runner, capable of sprinting a hundred meters, with hurdles, in about ten seconds.
Then there are the hints he's just Neil Flynn, his actor, fallen on very hard times.
Best summed up in this exchange after a particularly long anecdote about how The Janitor learned sign language:
J.D.: Was any of that true?
Janitor: Someone would have to read it back to me.
In lieu of the Janitor in season 9, Drew seems to have taken his place as 'dude with weird past'. So far we know that he had a meltdown his first time through med school which ended with him in prison, dressed up in a 'very flammable' dinosaur suit as part of community service, has been married, never uses public bathrooms after spending a month living in a gas station restroom, his parents believe him to be dead, he has an ex wife and stage-managed the Western leg of the `05 tour of Wicked.
Stephen Colbert's character shares some of his history with the actor (ten brothers and sisters, born in South Carolina) but the rest of it tends to change from episode to episode according to the Rule of Funny - including the names of his wife and children. Some fans have theorized that the character may be making it up as he goes along.
His book I Am America (And So Can You!) starts with his "first memory" involving a babysitter. A few chapters later, he off-handedly mentions that that he made that up.
This was done intentionally on Green Acres. Each season featured an episode in which Oliver and/or Lisa tell the story of how they met, but it's always a different story.
Doctor Who has explained away the creation of the Daleks in three different ways. Once in their debut story "The Daleks" (which didn't actually show it), a second time in a spin-off comic The Dalek Chronicles (which didn't contradict the first origin story) and finally in "Genesis of the Daleks".
Terry Nation wrote a book in the late '80s that reconciled "The Daleks" with "Genesis of the Daleks." Basically, the Daleks in "The Daleks" were a prototype Davros made before "Genesis of the Daleks." Their city was an experiment to see if Daleks could function autonomously. After he left them alone and got buried in rubble in the Kaled/Thal genocide, those Daleks wrote Davros out of their official history, preferring to ignore the fact that an "inferior" being had created them.
The series explained in "The Three Doctors" that Omega created the Time Lords by creating a black hole artificially. "The Deadly Assassin" says Rassilon did it. Later stories have reconciled the two explanations. (Rassilon and Omega were partners, Omega did the actual testing and got sucked into the black hole, Rassilon brought home the results)
Averted in New Who with the Cybermen: an alternative origin story, in which the Cybermen are invented on Earth by a wealthy human attempting to prevent his own death, is set in an alternate universe. The Mondas Cybermen didn't show up until 2010 (not counting the museum piece in "Dalek").
The Eighth Doctor Adventures novel Unnatural History suggests that the Doctor's many contradictory origins - being loomed, having parents, being half-human, coming from the 49th century, etc. - could all be true. This caused considerable debate at the time.
MacGyver presented two completely different versions of the title character's original meeting with Pete Thornton: a first-season version told in passing to give the characters' relationship a quick backstory and sense of long-term depth, and a full-blown (and totally incompatible) second-season version, told in flashbacks, that formed the focus of an entire episode (Partners). The underlying reason was that the show had a new producer, the concept had been overhauled and Mac's backstory was rewritten to eliminate his association with the military. The retcon also added a retroactive Arch-Nemesis, Murdoc.
The Odd Couple had multiple episodes depicting how Felix and Oscar first met.
On one episode of I Love Lucy, Lucy casually mentions that she met Ricky on a blind date. Later, the first episode of The Lucy-Desi Comedy Hour gives an extended depiction of how they first met, and it's a totally different story.
Parker from Leverage, has had several flashbacks to her past, which appear to all be true, but are somewhat contradictory: the first episode shows Parker, age 9 or so, running away from home after blowing up her foster parents after they yelled at her for stealing, another episode indicates that she was raised as an orphan, and another revealed she had a younger brother who was killed in an accident when she was twelve. All of these can be rationalized by her having one or more foster families, but it's still confusing.
In Stargate SG-1, Jack O'Neill's backstory throughout most of the series was that he was ex-Special Ops, and O'Neill wore a master parachutist's badge and later a space and missile operations badge on his dress uniform but never pilot's wings, but in an episode of Season Eight, Samantha Carter pointed out that he used to be a test pilot. This is likely an ass-pull by the writers, but given that he did pilot some experimental aircraft and that this backstory was never mentioned again, and that the only occasion when the viewers find out anything about O'Neill's background is when someone else mentions it, it's possible that Carter herself was mistaken.
Also, Vala's past. She was brought up on a nice planet with a conventional life (and fiancé) until she was chosen by Qetesh, OR she was sold to a weapons dealer and killed him to earn her freedom, OR she was brought up by her bitchy stepmother and conman father, and also how many times was she married? Vala is a habitual liar and loves to tell fanciful stories (especially in her earlier appearances, before her character development). The only things we know for sure is that she really was host to Qetesh at some point in her past, and she really does have a conman father. Beyond that, we may never know.
In Heroes Sylar's reason for being a killer was changed so often, he probably doesn't know himself anymore why he is one: inferiority complex, "hunger" as side effect of his ability, being manipulated by the Company and finally simply being a psychopath. This may be justified by the notion that he was lying (and possibly lying to himself) about his motives.
Captain Peacock from Are You Being Served? could never quite keep straight his stories of just what he did in World War II. The most likely story, however, is that he was in the Royal Army Service Corps—the logistics division (he says it when pressed about it, and wears the RASC tie throughout the series). Important work, but not front-line combat.
Mr. Goldberg, however, offered a different story - he and 'Corporal Peacock' served together in a cushy job in the cookhouse for most of the war. Had Goldberg been fired, we might even have seen the photo to prove it.
Detective Kate Beckett of Castle has elements of this trope. Aside from conversational information for characterization, there are the things she teases Castle about that are never substantiated.
Friends: Done very subtly with Chandler. You get the basics of childhood (his mother was an erotic novelist, his father was a gay drag queen, they divorced when was 9 and sent him to boarding school) but what's confusing is their treatment of him. On one hand he talks about how his dad was too enthusiastic coming to all his swim meets and you see his mom saying on national television that she loves him. Yet he also recounts how they prefered his imaginary friend to him, abandoned him on his first parents day and were callous enough to announce their break up during Thanksgiving dinner. Its not clear if they were just Amazingly Embarrassing Parents who made poor decisions or uninterested and put him through Parental Neglect or full out emotionally Abusive Parents.
An in-show version in the Sanctuary episode "Hero" — a comics-loving ordinary citizen discovers a suit which gives him superpowers. When Magnus' crew capture him, he feeds Will a made-up origin that's a hodge-podge of The Juggernaut, The Phantom and Green Arrow. Will buys it, until his comic-book loving friend Henry tells him.
In The Mighty Boosh, Howard and Vince frequently flash back to their shared past - but without any continuity about what this shared past has been. At one point they insist they are the same age, at another that Howard is ten years older than Vince. Vince may have been raised in the jungle by Brian Ferry or he may have gone to school with Howard. It comes down to Rule OF Funny, of course.
Married... with Children: Al and Peggy's marriage has a few different versions, but they all have alcohol and/or shotguns in common.
Most 30 Rock characters, due to the fact that most of the facts about their pasts are just throwaway punchlines ("My mother tried to send me to Vietnam to make a man out of me. I was 12.", " I definitely would have gone to my reunion, but the boat I was educated on sank.", etc.). If you try to compile them all together, they form a weird, somewhat contradictory, and definitely horrific image. The inconsistencies about Kenneth's past were turned into a Running Gag about him secretly being a long-lived immortal.
Lampshaded in Pete's case:
Pete: Look at my life, Jack. My father was a congressman, I was valedictorian at St. Andrew's, an Olympic archer, fourth guitarist in Loverboy — as a teenager! It's almost unbelievable! Jack: If it weren't all true, I'd say it doesn't even make sense!
Writers on The X-Files generally did a good job to keep the back-stories consistent, regarding what Mulder and Scully did before they started working on the X-Files and their family background, except when the ambiguity was the point. However, there was one deliberate change that did not please fans. Dana Scully's gold cross necklace, a frequent Tragic Keepsake and the symbol of her faith, has two possible origins. In season 2 episode "Ascension", Mrs Scully says she gave it to Dana on her fifteenth birthday, and season 5 episode "Christmas Carol" shows in flashback that teenage Dana and her sister Melissa both get their crosses for Christmas. The writers said they had known about the change, but they simply couldn't resist to use it in their Christmas Episode.
The character of John Black from Days of Our Lives. Originally, he was introduced as a guy with Identity Amnesia who'd undergone Magic Plastic Surgery as the apparent captive of a Big Bad. He escaped and took the name John Black from a sign on a wall. It was eventually revealed he was the Not Quite Dead Roman Brady and that was the role the actor was billed as for many years and lived through his "wife's" "death". Then they decided to bring back he original Roman/Marlena super couple, so it was revealed that "Roman" wasn't the real deal after all and went back to calling himself John Black. In the years since, he's had it revealed that he'd been a cop, private investigator, and a priest in his past. There have been at least two separate revelations about who his birth parents are. The current origin puts him as a cousin of some sort to Roman Brady and also related to the Big Bad. In the meantime, Wayne Northrop, the original Roman left the show again after a short time. That role was recast in a case of The Other Darrin and now played by someone who'd previously played a different role on the show. Then Northrop came back again in a completely different role.
The Golden Girls tended to have extended families that varied over the years. Blanche seemed especially vulnerable to this. She was the middle of three sisters, then a gay brother appeared. She had three sons and a daughter, but two different daughters were named during the show's run. It is also unclear whether or not she was faithful to her husband George - one episode says yes, another says no. And don't anyone ask her age.
Sophia also liked to make up preposterous stories about her past ("Picture it..."). These were played for laughs, usually inserting herself into trysts and feuds with famous people, and were (mostly?) made up.
In the second season of The Aquabats! Super Show!, each episode has one of the Aquabats telling a story about how the group came together. Naturally, all of these stories contradict each other, and none is treated as being any less valid than the others (with the possible exception of Crash's).
Primus and Unicron (as well as a few other legendary figures) have been established as "multiversal singularities", which basically means that they do not perceive time in the same way as lesser mortals and therefore retcons any seemingly conflicting stories of their past.
The backstory to The Haunted Mansion is basically whatever the cast members decide it is that day.
The burning cabin on Tom Sawyer Island was originally due to an Indian attack. As The Savage Indian fell out of favor, the backstory was changed several times before it became a regular cabin.
The soundtrack played at Great America's roller coaster "The Demon" variously traces the ride-possessing demonic entity's origin to the Louisiana bayou, the bottom of the Hudson River, or debris from a battle between alien spaceships that crashed in the Southwest.
Gorillaz's bass player / leader Murdoc Niccals can't decide if he was an abused child that grew up in the 1960s/70s, or if he is an immortal being who has watched time since it's very beginnings. Then again, you get a different answer from him on generally anything, depending on how knackered he is.
There have been wildly conflicting stories about how Lou Pearlman first approached Chris Kirkpatrick about starting another vocal group, but the commonly accepted ones are that Pearlman spotted Chris performing in a doo-wop group or that Chris auditioned for Backstreet and was rejected.
In Greek Mythology, for example, different authors gave different parents to many heroes and deities, and told events in their pasts differently. The Kabeiroi, Kouretes, and Korybantes, related sets of minor deities, had several different genealogies and origin stories. Humanity itself had separate creation myths in different cities, along with different explanations for how they got fire, writing, and so forth.
There were two stories of why Hephaestus had a bad limp: either he was born lame, or Zeus threw him off of Mount Olympus during a quarrel and he was injured in the fall. Homer told both versions in The Iliad.
Ancient Egyptian authors also differed on the parentage of various gods. This isn't surprising, given that such family relations were often more a matter of local cult rather than "myth" as such. By the end of the New Kingdom, many gods were worshipped in threesomes identified as husband, wife, and son, and temples in different regions used different combinations of gods.
The childhoods of The Undertaker and Kane (who are half-brothers) have come to be subject to this. The original story was that The Undertaker was an arsonist who burned down his parents' funeral parlor, killing both parents and leaving Kane horrifically disfigured. Other versions, however, pointed to Kane as being responsible for the fire. Thirteen years later, it was revealed that Kane's father actually survived the fire — and that he was none other than Paul Bearer.
Done with the entire species of illithids (Mind Flayers) in Dungeons & Dragons. One of the earlier versions says that they're mutants outcast from a long-gone human society in the Astromundi crystal sphere (solar system). Another version puts them as emerging when parasites from "the Outside" entered the game's reality and began bonding with and mutating humanoids, and went on to rule an interstellar empire millennia ago which has since fallen. An old Dragon magazine article depicts them as invaders from an alternate Prime Material Plane, trying to reshape whatever world your characters are from in the image of their homeworld. A later version says they're from the future and traveled back in time to escape a nameless enemy that was destroying them, and to prepare better for that enemy while in the past. It's ultimately left up to the Game Master to decide which of these is the "truth," or if perhaps they're all successive layers of lies used to disguise the illithids' origins and that the latest retcon is just another lie. However, in the 4th Edition rules, Mind Flayers are once again from the Far Realm - beyond the borders of the universe. This certainty may be only because there haven't been enough years into the new edition to let their webs of deceit get fully developed yet, however.
An interesting but ultimately unrelated note on the time-traveling origin: A person can still take "Heritage" feats, special character options that indicate one's bloodline co-mingles with that of the relevant race/species (Fey Heritage, Draconic Heritage, etc) for Illithids. For most heritage feats, this implies an ancestry speckled with Interspecies Romance. However, in this case Illithid Heritage actually means you're actually one of the ancestors of the Illithid bloodlines.
World of Darkness gamelines tend to play with this.
In Werewolf: The Apocalypse, pretty much everything regarding the how and why of the War of Rage, the creation story of the Triat, and the birth of the were-races are told from the point of view of a member of whichever race the book you're reading is about, and so every version is from an Unreliable Narrator.
There's also the Rasputin situation. Numerous historical characters were written into the Old World of Darkness. Two different writers used Rasputin as a character, not knowing about the other's use of him, and their versions had two different backstories. When this discrepancy was pointed out, the company decided to run with it. Several writers began using Rasputin as a character, giving him a different backstory each time. These multiple versions of Rasputin became one of the unsolved mysteries of the original World of Darkness.
In the New World of Darkness, multiple explanations are given for several aspects of the game world so that the Storyteller may pick and choose which ones she likes.
In Changeling: The Lost, for example, there are several possible reasons for why the Gentry may kidnap humans and how the True Fae come to be. At least, until you read the supplement book that says that True Fae are what happen to Changelings when they hit Wyrd 10 and Clarity 0, and they kidnap humans because that's how they reproduce.
So far, we have two separate explanations for the Tunguska event (a Promethean tried to summon an arch-qashmal, and one of the Knights of St. George tried to summon a Faceless Angel). Anyone's guess how many we'll have by the time the line folds.
And then there's Atlantis. Atlantis could have been the real first city, Atlantis could have been an allegory that the minds of mages made real, Atlantis could be a far-future event whose collapse was felt eons in the past...
And let's not even go into how this interacts with the Uratha tales of lost Pangaea...
Dungeons & Dragons 4e core setting Points Of Light does this with pretty much all of the deities. Fairly justified; they've been around for so long that the details of their origins are wrapped up in legends. Notably, Asmodeus has been given probably the most information on his origins, most of them being at least somewhat contradictory.
And then there's the Raven Queen. Depending on what you look at, she's a True Neutral goddess of death as part of the life cycle, an evil former consort of Nerull who overthrew him to gain his title as God of the Dead and now plots to destroy the other Gods so she can gain that title that she believes is rightfully hers rather than her lesser title of Goddess of Death, or a selfish and power-hungry goddess that epitomizes the reason True Neutral is now Unaligned.
In Warhammer 40,000, the God Emperor has some shades of this. Originally he was created by a group of incredibly powerful shamans in the year 8,000 BC. Newer versions keep the 8,000 BC date but drop the shamans. Then there's the possibility that the Emperor was actually born in the Age of Strife (26,000 AD or so). The current edition and Horus Heresy series mention all of the above, but have him intentionally obscuring the issue even before ten thousand years of conflicting dogma.
Steambot Chronicles had a literal version of this, where after meeting with Mallow you can recover from your amnesia and reveal your past. Or not, if you didn't feel inclined. Unfortunately, this leads to some incredibly stilted dialog in the following scenes.
[Name] is... the son of a baker... fast... ...and a lone wolf.
As if the Warcraft lore didn't see enough changes/retcons, the setting also features a fair dosage of time travel. Certain forces can tamper with the timeline, while the Bronze Dragonflight tries to fix it. In ''World of Warcraft, the Caverns of Time feature a set of dungeons where the players assist them by whatever means possible. For instance, there are two versions of Thrall's escape from imprisonment: either a bloodless escape during a distraction, or a group of strangers assaulting the keep and a nearby town.
Although at the end of that one, the bronze dragon that was guiding you implies that after you've destroyed the last of the Infinite Dragons who were trying to alter the time stream, he would alter events so that the original bloodless escape is what everyone will remember.
This is quite literally true for Commander Shepard in Mass Effect. At character creation, Shepard's appearance, gender and military specialization are filled in by the player, as well as two different sets of background details, with three choices each. Some of them actually affect how the plot unfolds - the early backgrounds each have a unique mission in the first game, while the military ones cause minor dialogue changes at various points.
In Knights of the Old Republic II: The Sith Lords, you have the option in several conversations to choose certain aspects of what happened in your past, as well as what happened in the first game. You can even choose non-canonical endings for what happened in the first game, and the rest of the second will react accordingly.
The game takes this to a whole new level with its Player Character: each of the six available "Origins" for the Warden has a separate starting quest chain, with a follow-up in one of the main story quests later on.
In-story, Flemeth combines this trope with Unreliable Narrator. At least two different versions of her story, the legend and the story she told Morrigan, have been told thus far, and Morrigan even says she doubts Flemeth told her the truth.
Dragon Age II provides one of three choices for how the game begins from the first game (aside from importing a save file from Origins): "Hero of Ferelden" (a Big Good Human Noble defeated the Archdemon and survived the fifth Blight, Alistair is king of Ferelden), "The Martyr" (a cynical Dalish Elf sacrificed herself to kill the Archdemon and end the blight, Alistair and Anora marry and rule Ferelden together), or "No Compromise" (a Determinator Dwarven Noble let another Grey Warden die to defeat the Archdemon, Alistair is exiled from Ferelden, and Anora is queen).
Dragon Age: Inquisition: After some early reports that you could only play humans with differing backgrounds, it was announced that you will have access to human, elf, dwarf and kossith / qunari Inquisitors. They'll have different explanations for joining a human Church Police, but they won't be playable like in Origins - the Inquisitor's story will start in the same place.
In The Suffering, your actions in the game dictate how Torque's family died via Karma Meter. There are three endings. In the good ending, they were murdered and you were framed. In the neutral one, Torque killed them on accident, and in the bad ending, he murdered them all.
This was originally cut from the game and was reintroduced by an official patch.
In The Elder Scrolls II: Daggerfall, the player can choose to determine his character's class, reputation, ethics, abilities, etc, through an extensive survey of his background... or can choose to have it all automatically generated. One of the questions asks what item you received as a gift from the emperor. If you choose the ebony dagger, you start the game with that weapon, which is substantially superior to other weapons at that level.
Mount & Blade has a set of questions in the character creation that asks you about your character's past. This sets up your character's starting stats and equipment.
Mario, having a canon that's basically built on Rule of Fun (as well as implied), has a few different origin stories. Americans of the 80's and early 90's might have known Mario and Luigi as two plumbers from Brooklyn who got sucked into a pipe and ended up in the Mushroom Kingdom, but that was only invented by DIC for their threeanimatedseries based on the games, plus newer ones imply that they've always lived in the Mushroom Kingdom, as little sense as that makes. Other regions just avoid origin stories.
Note that the Mario Bros. have never been seen in the Mushroom Kingdom between the time they were babies and the present. It can be pretty easy to put the pieces together and say that they were taken to Brooklyn to be protected, because, seriously, who in their right mind wouldn't move after all the stuff that happened to Baby Mario and Baby Luigi?
Like his rival Mario, Sonic the Hedgehog has a fairly inconsistent past as well, though the video games themselves have never done much to elaborate on his past. Tails, Eggma..., er, "Dr. Robotnik" and especially Blaze have similar inconsistent pasts.
Street Fighter: Charlie Nash encountered M.Bison (North America; "Vega" in Japan) during a [wartime mission/secret operation/solo assignment] in [Cambodia/America/Venezuela/a Shadaloo base near Thailand]. Charlie prevailed over the dictator but tragically [turned his back and got zapped/was blasted by a Shadaloo gunner/failed to escape the base before it blew up/suffered some mysterious terrible fate]. Guile wanted to prevent it, of course, but [didn't know Charlie was in danger/wasn't strong enough/wasn't fast enough/realized Charlie did what he had to do]. One thing is certain, though, [he's dead/he's missing, presumed dead/he got turned into Shadow/and as soon as I figure out what the hell it is, I'll let you know].
Touhou: Almost but not quite literally the case for Sakuya. Perfect Memento in Strict Sense offers multiple backstories for her, but they're all rumours going around the village, and it's unlikely that any are actually true.
Due to the jump of platform from PC-98 to Windows, at least three other characters have conflicting past(s): Alice is either a normal human turned witch, or the daughter of the Goddess of Pandemonium. Marisa is either an acolyte of necromancy or a relic hunter. Yuka is either a lethargic reality warper or an extremely sadistic flower youkai. Furthermore, an Eternal Recurrence is strongly implied (the 60-years cycle), so it's not like the pasts are mutually exclusive.
The premise for Hail to the Chimp is that former king, the Lion, resigned in disgrace due to a "scandal" that neither the box nor the instructions describe in any way. There are several possibilities as to what this scandal is, one of which is chosen at random each time you load the game.
In Fallout: New Vegas, there are several contradicting stories about the past of Legate Lanius, from being a Legionary at the age of 12 to being press-ganged into joining the Legion. Even Joshua Graham, the former Legate states that he's never even heard of Lanius during his time in the Legion. In Lonesome Road, Ulysses, a former Legion spy considers the idea that Lanius wasn't always the same person considering that no one has ever actually seen him without his mask.
Lonesome Road also fills in the backstory of the Courier, though only by choosing certain dialogue paths. There's an achievement for getting all six, and as a result is arguably this trope.
In the original game Betrayal at Krondor, Gorath was from the Green Heart, and moved his tribes to the Northlands during the Riftwar (Possibly making his tribe the one that Longbow tricked into fighting the Tsurani during the seige of Crydee). In the novelization, Krondor: The Betrayal, his tribe was originally based near Sarth, and moved to the Northlands over a century earlier when the Keshians colonized the region.
In Final Fantasy VII, about five versions of Cloud's past in Nibelheim have been officially released so far. At least one of these (the most detailed) is eventually revealed as a lie within the story, although due to the circumstances of the lie and due to it covering more than the others do, it's still debatable whether huge chunks of it are true or not. The other four are wildly divergent with Crisis Core and Final Fantasy VII`s "true" account having roughly equal canoninity despite Crisis Core having an entirely new character provoke Sephiroth's downwards spiral and despite the fact that Zack doesn't get the opportunity to do all the silly things Final Fantasy VII'`s "lie" account implied he did. The OVA Last Order is also diverging, but probably the most radical in terms of what it implies about Cloud's past - it contains a strange scene where Cloud summons a great strength and his eyes begin glowing, causing Sephiroth to ask "What are you?", long before Cloud was granted with Mako abilities in the original Final Fantasy VII, implying that Cloud isn't human or was experimented on previously.
The events of Last Order have been explained that since most of the animated-special takes place from the Turks' point of view (the opening scene shows the report on the Nibelheim incident, which implies that the whole flashback is from what the official Shin-Ra history report says) its account is different from what was shown in the original game and Crisis Core.
This happens in Hyperdimension Neptunia and Hyperdimension Neptunia mk2, due to the two taking place in alternate continuities. In the original, Compa meets Neptune after she falls out of the sky, and IF is met (and unknowingly tricked) into joining Neptune and Compa's party a little later. In the sequel, Compa and IF were childhood friends, and they met Neptune (and Nepgear, who is exclusive to the sequel) after she fell off the top of a 10,000 story tower.
When starting a game in Liberal Crime Squad, the player may choose events in the squad founder's past, or let the events be randomly selected. These events inform their in-game attributes and skills.
You get to do this in Guild Wars 2. However, all it changes in game is your personal story for the first twenty levels.
The Joker, unsurprisingly, has one of these in Batman: Arkham City. He's just finished telling his Start of Darkness story to Hugo Stange (its the same one from The Killing Joke), and Strange points out just how many different stories the Joker has. The only common link is that he blames Batman in every one. The Joker even cites this trope verbatim:
"A wise man one said, if you're going to have a past make it multiple choice."
Notably, Strange accuses Joker of just using this trope as an excuse to never face up to his past and what he's become. Unlike the other rogues Strange interviews, he fails at getting under the Joker's skin.
Subverted in Tsukihime: with each separate route, the minute-but-important details of Shiki's childhood appear to change or even be downright inconsistent with the other routes. Only after finishing all the routes can the actual backstory be inferred, by piecing together the revelations and details from each route (like a convoluted puzzle).
In Umineko: When They Cry, we're presented with two different versions of Beatrice's past, one fantastic and magical and one more mundane and rather tragic. It's all but stated that the latter is her true past.
Inverted at the end of Really? Really! with Asa's hair length. Kaede asks whether Rin prefers Asa's hair short or long and allows you to choose which one you prefer. A few in-game minutes later, Asa appears with the hair length that was chosen, despite being nowhere near Rin and Kaede when the answer was chosen.
Plot Hole (yes, that's his real name) from Acrobat, during a story that was supposed to tell his secret origin, told multiple stories, ripping off the origins of Superman, Batman and partly Spider-Man, making Plot Twist a villain in every single one - they don't match with each other, or Plot Twist's origin, and hint that Plot Hole doesn't even know what his Arch-Enemy really looks like. The only thing he's sure is that he was somehow created by Plot Twist, but even that cannot be found as absolute truth, because he's obviously obsessed with him.
In thisSuper Stupor webcomic, a character is grieving that her background was retconned (you know, it never happened), yet she still remembers it.
Doctor Insano, enemy of Linkara and Spoonyis this trope. He has so many multiple origins, including ones where he's Spoony from future, where he's Canadian science geek Wayne Schlumper, and where he was a woman before Linkara punched the fabric of The Multiverse, that when people tried to put it together in any continuity, Word of God said there's no continuity. There is only Insano.
So far he's been a failed clone of Spoony, from the future, a different person, the same person but not somehow (left unexplained), and an alternate personality that was given up "in the past". All of these origins are equally canon.
In CR's overview of Insano, he theorizes that there's really three of them—one a time-travel duplicate generated by Time Compression who violently tries to kill Spoony, one a clone made by Linkara who lives with Spoony and is more friendly, and the alternate personality. He finishes by guessing that Original Spoony also had an Insano persona, and thus there could be a fourth, Black Lantern Insano as well.
According to To Boldly Flee, Insano and Spoony have always been separate people, and Spoony's ability to transform into Insano in Kickassia was a temporal anomaly retroactively caused by the Plot Hole. Of course, this is just yet another alternate backstory.
There is no single definitive version of The Slender Man Mythos. Even his appearance, though built around a basic template, varies from story to story. The central tenet is simply the Rule of Scary. This extends to Slendy's origin story. If it comes up it will completely contradict another story's idea of it. This is probably the reason most stories avoid giving Slender Man a definitive origin (that and to avoid a Voodoo Shark).
Marble Hornets season two features the protagonist doing this (badly). Jay goes through three contradictory stories explaining his presence in the hotel to Jessica, much to her confusion, and, eventually, disbelief. The real answer, of course, is that he doesn't remember. And neither does Jessica remember how she got there.
The Slender Man fic By the Fire's Light features an origin for the Slender Man that might only be retroactively true since people in-story believe it. Whether the Slender Man existed before this in its current form in-story is left up to debate.
The Foundation itself according to SCP-001 propositions. In fact, according to the article, it's possible that two or more of the different stories are true at the same time.
In one Legion of Net.Heroes story, a Cosmic Entity decides to rewrite a mortally-wounded Squid Boy to both save his life and make him easier to use as a character. (The LNH has never had much use for the fourth wall.) As part of the process, Squid Boy (now Squidman) is asked to describe his origin story. Since Squid Boy dated from the very early days of the LNH when the whole thing was a joke, he'd never actually had an origin story, and suggested several possibilities before finally settling on one, which locked it into continuity as his actual origin.
The Venture Bros. gives several varying explanations for both the origin of Phantom Limb and how Billy Quizboy ended up with a robotic hand, with the Monarch's being the most plausible. When Dr. Venture finally asks him about it, point blank, Billy merely replies "Excellent question. I have no idea."
They later gave them both a definite past. The Monarch's version, while not complete, did get most of the facts right (Phantom Limb was Billy's professor, not roommate and the latter had already lost his arm to a rabid pitbull prior to the incident). The comment about him not knowing ended up becoming a Cerebus Retcon because of this. Turns out he doesn't remember because OSI wiped his memory. When Billy learns of the deception, he rather suitably flips the fuck out.
Darkwing Duck is given at least three mutually incompatible origin stories over the course of the series. Word of God says this was a deliberate invocation of Rule of Funny - and if they'd had more episodes, they'd have written even more...
Darkwing's origins "multiple origins" were always Played for Laughs, but there were never any real inconsistencies. Two of them were obviously Darkwing making stuff up (his baby alien story and his adventures as a privateer), and the rest were pretty compatible. He was first inspired by his time-travelling older self. Then, he took up the Coat Hat and Mask at his senior prom, while battling Megavolt, and finally, he went to China to study Quack Fu under Master Goose Lee.
The TaleSpin episode "The Time Bandits" (itself a Recycled Script from DuckTales) says that Rebecca inherited Higher For Hire from her father, despite the Five-Episode Pilot having introduced her as buying Baloo's air cargo company after it was foreclosed upon.
As the information in The Time Bandits was given by a government employee of Thembria. Nothing's saying that official facts have to be truthful.
The Simpsons not only has a multiple choice past for pretty much every character, but even a multiple choice future. As the show exists in a floating timeline however, this is pretty much unavoidable. Heck, one of the show's flashback episodes was set throughout the 90s...the decade which started right along with the show itself. Talk about trippy.
This trope was originally supposed to be played straight for the origins of Herman's (the fellow who runs Springfield's military surplus store Herman's Military Antiques]) missing arm, but this idea was dropped after his first appearance (to this day, he's only told us that he lost his arm when he stuck it out the window of a moving school bus).
The series had multiple explanations for why Homer lost his hair including having torn out his hair after finding out Marge was pregnant and as a side effect from an army experiment he participated in to avoid dinner with Marge's sisters.
In Futurama, the circumstances of Bender's "birth" change every time the event is brought up.
On The Fairly Oddparents, Timmy's mom and dad have several different versions of how they met. When it was first shown, it was stated that they began dating as kids and became a couple when Mr. Turner gave her a trophy he won. The second time it was show Mrs. Turner dated Dinkleberg until college, when Mr. Turner got her on the rebound. Other episodes say they met through a "threatmantic" letter or "in the sports aisle".
Timmy and his fairies have screwed around with time so much they could all be possible.
Pinky and the Brain had four different episodes with flashbacks to the duo's childhood and when they were first genetically altered. They all contradict each other.
Sponge Bob Square Pants had different versions on how Mr. Krabs got the Krabby Patty Secret Formula: one has him tell it was an old Krabs family recipe, the other as passed to him from his grandmother, an entire episode showing that his then-friend-now-enemy accidentally made it, and so on and so forth...
Rocko's Modern Life: Rocko is stated in some episodes to have known Filburt as a kid, and in another, he says they met Heffer in high school. In other episodes, though, he apparently left Australia and came to O-Town as an adult. Word of God says that the latter is definitive, anything else is just the characters misremembering. Filburt meets Rocko in different scenarios. Word of God said it's because Filburt just has bad memory.
On Invader Zim, Ms. Bitters gives multiple back stories, such as imploding in a spaceship when she was a child and being a fairy princess in a magical forest (before running into a bug zapper). According to Word of God, however, she's always been in the same place she is now; the "skool" was actually built around her.
On Jimmy Two-Shoes, Lucius VII froze his father, Lucius VI, making him a psuedo Self-Made Orphan. Exactly how always varies. At first it was because they had a heated argument, then because Lucius VI lost a bet, then because Lucius VII's talking bird told him to.
Jerrica Benton (AKA: Jem) either inherited Starlight House from her father, or lived there with Kimber (her sister) Aja, and Shana all her life. In fact, it may have even been both.
In The Transformers, the Constructicons had no less than three wholly separate and contradictory origins in the cartoon alone. First, that they were built on Earth by Megatron in 1985. Then, that they were Autobots from Cybertron reprogrammed by Megatron millions of years ago. Then that they were Decepticons who built Megatron in the first place years before that.
The Batman version of Killer Croc, who is either a former carnival freak, government experiment, or the result of voodoo.
It's implied in an Arthur episode where Buster "saves" a cat on a tree that Buster invokes this trope when he lets heroism get to his head. Buster is seen bragging to some reporters about how he got the cat down, Francine mentions that she's starting to get bored with Buster's heroism stories, and then Binky arrives and says that he's not bored of his stories, as they're "always different."
Archer's origins are left deliberately vague. In Double Duece, Archer is stated to have been born in Morocco while Malory was running from Nazi spies (around 1938), one of his possible fathers was an Italian executed by an Operation Gladio operative for speaking out against fascism and was about six or seven when World War II ended. He's also shown listening to Woodhouse read a telegram from Malory about Operation Ajax in 1953, which would make him 15, but he looks younger than that, and "Once Bitten" states he was six when Malory was involved in the CIA-backed Guatamalan coup d'état, which took place in 1954, which would place Archer's birthdate in 1948. One possible explaination is an Alternate History.
Joe Swanson from Family Guy originally claimed that he lost the use of his legs when he fell off a roof chasing the Grinch and broke his legs. Many seasons later, he reveals that he lied out of shame and that a drug lord shot him in the legs repeatedly.
On Goof Troop Max and PJ met at age 11 (shown in "Everything's Coming Up Goofy" and "Good Neighbor Goof" and mentioned in "Goodbye Mr. Goofy" and "Pistolgeist"). Except that "Wrecks, Lies, and Videotape", "Tee for Two", "Goof Troop Christmas", and "Tub Be or Not Tub Be" all suggest that Max and PJ have always known each other. The backstory is irrelevant to most things except for the nature of Max and PJ's relationship—namely, the first backstory provides an explanation for PJ's Undying Loyalty towards Max; the second does not. This can be a little jarring considering "Tub Be or Not Tub Be" supports the second backstory and features an undyingly loyal PJ and a relatively unsympathetic Max.
Cars Toons series, Mater, the resident Cloud Cuckoolander, always boasts about his past where he involved in something big such as being a famous racer, a spy, a firefighter, or an elite detective. Lightning never believes his claims, but the end of each episode always proves that every single of Mater's narrative is a true story.
In various interviews, Yul Brynner gave several inconsistent accounts of his early life to make himself seem mysterious to the public.
Over the years, comedian Dave Allen's act incorporated a huge number of different stories about how he came to lose part of his left index finger.
Leon Redbone is notorious for giving various stories of his birthdate & his parentage, as well as claiming authorship of many songs which existed prior to his probable birth.
Joe Kucan became Kane from a scratch off lotto ticket. He won a special election. He won a carnival game. He found the prize in a crackerjack box. He was in the right place, at the right time. He was the Dramatic Director on a project with almost no funding.Using employees was cheaper than hiring actors.
Meat Loaf often tells people how he got that name, only he never tells the same story twice.
The origins of baseball are subject to this trope, as it's hard to exactly pinpoint A. When/where the first game of baseball was played, B. Whether a sport referred to as "base ball" in early documents from The American Revolution was an early form of the current sport, or just a similarly-named but unrelated sport, or C. Which game counts as the first "official" game: any of the games played during the The American Civil War, the early game played at Hoboken, New Jersey (depending on whether this early version counts as a version of the modern game or just a precursor), or perhaps an unknown, unrecorded game. The game played at Cooperstown, supposedly organized by Abner Doubleday, is now considered fictitious, but it used to be considered a contender to be one of the great game's possible origins. Many historians view all of these early games as being partial examples of the game we know today, but that the game evolved a bit with each one.
People who are lying tend to do this when asked to repeat details of a story.