Batman's greatest enemy. The Joker himself has stated that he prefers his past to be "multiple choice," and while many possible origin stories have come and gone, not a single one has ever been proven. Joker may have been a failed comedian, sure, but he also might have been a bored bank robber. Or maybe even... Batman's brother?

This mystery is part of what has made the character such an icon. It's scary to imagine what kind of tragedy could possibly transform a regular man into such a wild and unpredictable force of nature. Was it really all because of "one bad day?"

Chances are, we may never know the true story of how the Joker came to be. But that doesn't mean it isn't worth trying to shine a flashlight into the mystery, and follow the little bread crumbs that have been left for us over the years. Here are 15 Wildly Different Origin Stories For The Joker.

15. He Was the Leader of the Red Hood Gang

The Joker in The Man Behind the Red Hood comic book cover.

While there are many, many tales about how the Joker came to be, there are two story elements that repeat themselves quite frequently. First, there's often a failed heist leading to an unintended chemical bath. Second, there's a red hood. Or the Red Hood, to be exact.

The exact motivations, organization, and size of the Red Hood Gang varies, depending on the story. Either way, what makes the Red Hood Gang unique is the M.O. of their leader — known as the Red Hood — a brilliant criminal mastermind who always wears a red, dome-shaped helmet. The turning point occurs when the Red Hood Gang attempts to rob a chemical plant, and Batman intercepts them. Desperate to avoid capture, the gang's leader leaps into a vat of chemicals — or trips, or is accidentally dropped by Batman, depending on the story — and then is seemingly burned alive. In actuality, the chemical vat contains a drainage pipe that empties out into the river, and the unnamed leader washes up on the shoreline. There, he discovers that his skin has been stripped of all pigmentation, his lips are red, his hair is green, and his cheeks have been warped into a permanent smile.

That's the standard story. But then Alan Moore's 1988 classic, The Killing Joke, added a new twist that changed the entire context of it — and for the first time, presented the sinister villain in a more sympathetic light.

14. He Was a Failed Comedian With A Pregnant Wife

Red Hood Killing Joke

Before The Killing Joke, most versions of the Joker's origin presented the character as having always been villainous, an experienced criminal who just went one step further. Alan Moore's brilliant innovation was to ask a question that no one had ever pondered before: what if, once upon a time, the Joker was just a regular person like the rest of us? What if maybe, just maybe, all it takes to turn a normal human into the Joker... is one bad day?

The heartbreaking story in The Killing Joke presents the notion that the future Joker was once an engineer at a Gotham chemical plant who one day decided to quit his job, and follow his lifelong dream of becoming a stand-up comic. Unfortunately, his ion only gets him so far; no one laughs at his jokes, and his new career as a comedian is a financial failure. Poor, desperate, and broken, the comedian struggles to his pregnant wife, Jeannie. In a last-ditch effort to make money for his family, the failed comic agrees to the manipulations of a low-rent criminal gang who want him to help them break into the same chemical plant at which he once worked. In order to protect his identity, they give him a dome-shaped red helmet to wear, so that he can pretend to be their leader, the infamous "Red Hood." In actuality, the Red Hood is a patsy, and the gang uses this guise in order to keep attention off their own backs if they get caught.

Then, the comedian's one bad day lands on him like a piano. His pregnant wife dies. The comedian tries to get out of his criminal agreement, but the gang forces him to stick to the plan. At this point, a familiar sequence occurs, with Batman assuming that the comedian is the leader, the comedian taking a dunk in the chemicals, and so on. What differs here is that when the Joker wakes up to see the reflection of his new chalk-white face and twisted smile, it's just the final nail in the coffin.

13. His Aunt Eunice Washed Him With Bleach

Joker's Aunt Eunice DC Batman

While The Killing Joke origin is the closest to an official one there is, the Joker does stipulate that he prefers his past to be "multiple choice," so he's an unreliable narrator. There have been other theories floated around, many by the Joker himself, and the "Aunt Eunice" story is one of the most horrifying.

In this possible origin, there is no chemical bath, no factory, no Red Hood. Here, the Joker's problems begin in childhood; as a little boy, he is raised by his Aunt Eunice, an abusive sociopath. As presented in the Joker's oral description, the two of them live in a rundown apartment, where he is regularly starved, beaten, and screamed at. He has no friends, his only companion being a small stuffed animal with a purple hat that he desperately clutches onto at all times, until Aunt Eunice takes it away from him.

Perhaps the most horrifying mistreatment that the boy suffers is when Aunt Eunice, furious at him for "never washing his ugly face," decides she's going to clean him up the same way she cleaned up her husband — with bleach, and a scrub brush. It's implied that Eunice frequently washed the boy down with bleach, until his skin eventually became white. This Aunt Eunice story offers a different explanation for the Joker's strange appearance, as well as his twisted mental state.

12. He Was Jack Napier, Killer of Batman's Parents

Batman argues with the Joker about their origins in Batman (1989)

Everyone re Jack Napier. He was arguably the main character of Tim Burton's 1989 Batman film, since the movie's entire plot revolves around his story rather than Bruce Wayne's. While Batman's origin is held off until later in the film, the Joker's origin is revealed in real time, as we watch the saga of a clever mobster named Jack, who one night falls into chemicals — either by accident, or because Batman dropped him — and then wakes up with a giggly new bounce in his gait, a white face, and a megalomanical desire to take over Gotham.

There isn't a great deal of mystery to Burton's Joker. We know who he is, we know how he came to be, and we even see how he dies. While this clear sequence of events is a divergence from the enigma surrounding the comic book Joker, the bigger change is that Burton chose to involve the Joker in Batman's origin story, by framing Jack Napier as the killer of his parents via flashback.

Fans never took well to this drastic change in the mythos, so it was never incorporated into the comics. Really, there are enough parallels between Batman and the Joker without forcing such an unrealistic coincidence into the story.

11. There's That Story He Told Harley Quinn...

Joker and Harley Quinn in Arkham

Throughout the Joker's long and demented history, there Suicide Squad earlier this year.  While we know that the Joker likes telling varied and contradictory versions of his own story in order to keep others guessing, it's interesting to peek in on the tale he spun for the woman he has shared his bed with.

In fact, back when Harley is first assigned to be the Joker's counselor at Arkham Asylum, the fiendish murderer actually tells Harley a sad little tale about his childhood with the direct intention of manipulating her into falling in love with him. Needless to say, it works. As such, it's hard to buy the Joker's story, since it seems so poised to tug on Harley's heartstrings; according to him, he spent his childhood years suffering at the hands of an abusive father. His rare moments of happiness came when his father would bring him to the circus, and while there, he would see his father actually laugh at the clowns — the only time his father ever laughed  — particularly when the clowns dropped their pants, and other slapstick gestures. One day, his father's pants dropped. Reminded of the clowns at the circus, the future Joker burst out laughing, only to receive a broken nose in response.

Whether this particular clown story is true or not, it's not the last time we'll see the Joker talking about having a problematic relationship with his father.

10. He Was Gotham's Slickest Criminal — And His Insanity is Just an Act

The Joker's origins in Case Study comic by Paul Dini and Alex Ross

One argument that many have raised against the more sympathetic takes on the Joker's origin is that the Joker's cunning brilliance, sharp reflexes, and knowledge of the criminal underworld couldn't have come from nowhere. If the Joker had been a regular guy before he turned into a murderous clown, it would seem more likely that he had some serious experience in Gotham's mob scene, and perhaps could have even been a major player behind the scenes.

The story Case Study, by Paul Dini and Alex Ross, suggests that the Joker might not even be crazy. Perhaps all of his madness is just an act performed by a perfectly sane, perfectly rational person, feigning insanity as a form of revenge against the city that ruined him.

Case Study details a medical report on the Joker, written by Harley Quinn before she was assigned to the Joker. The report suggests that the man who would be the Joker was a major player in Gotham's crime scene for many years, casually avoiding any charges or reputation through a combination of cleverness, wit, and ruthlessness. If this man was the Joker, even back then, he had a tendency to constantly use new names and new identities, always slipping under the radar as he overthrows major crime bosses and takes over their territory. The decision to become the Red Hood, here, was not of desperation, but for the thrill of it; this nameless crime boss had grown tired of being so powerful, and wanted to have reckless fun like in the old days.

9. He's an Immortal Demon

Joker Pale Man of Gotham DC Batman

How has the Joker lived so long, despite one near-death after another? How does he always survive those big falls, those exploding factories, those dips into the harbor, those burning buildings? What if he's... immortal?

One of the most out-there theories regarding the Joker's origins is that he may be older than Gotham City itself. The Endgame storyline proposes that throughout Gotham's history, countless inhabitants have fallen prey to a terrifying white demon called the Pale Man of Gotham City. It is theorized that the Pale Man was once a regular human who came into with a chemical compound named dionesium, one of the main ingredients in Ra's al Ghul's Lazarus Pits, which then rendered him immortal. Since his exposure to dionesium, the Pale Man has haunted Gotham for generations, like a mystical Jack the Ripper, always emerging during the city's most catastrophic events.

If the Joker is the Pale Man, then it means that he's been pretending to be a regular human being all along, merely for the sake of toying with Batman. However, the finale of Endgame suggests that the whole thing is a massive ploy on the part of the Joker, to mess with Batman's head. Talk about twisted games.

8. The Animated Series Origin

Epic Joker laugh from Batman Mask of the Phantasm

Without question, one of the most enduring and celebrated incarnations of the Joker is the one featured in Batman: The Animated Series. Mark Hamill's voice is so distinctive that it's been featured in multiple movies and video games even in the years since the DCAU ended, and the way that the Joker was written combines the best of every version. Hamill's Joker is one who can be hilarious one moment and sinister the next, equal parts charismatic and ruthless. He's also totally obsessed with his bat-eared adversary, at one point even shown shedding tears when he believes the Batman to have finally died.

The Animated Series never delved too deeply into the Joker's beginnings. However, the clues that the series does show regarding its Joker backstory are straight from the classic origin, with the character presented as having been a gangster (and possibly a hit man) who at one point fell into chemicals that bleached his skin.

One unique reference points occurs in Batman: Mask of the Phantasm. The beloved film tells an epic love story about Batman's beginnings, culminating in a present day three-point climax between Batman, Andrea Beaumont/The Phantasm, and the Joker. The film reveals via flashback then when the pre-Joker worked for the mob, he was personally involved in the murder of Carl Beaumont, Andrea's father, and the man who was almost Bruce's father-in-law. In one neat plot twist, it turns out that the pre-Joker and a pre-Batman Bruce Wayne actually crossed paths at one point, if only for a moment, neither of them realizing that they were encountering their greatest enemy for the first time.

7. He's Actually Batman's Brother, Thomas Jr.

Batman and the Joker Walking Arm in Arm

Then there's this doozy, which has actually gained a lot of traction in many online circles.

The theory is based around the idea that the Joker is secretly Thomas Wayne Jr., Bruce's long lost older brother. An enormous collection of evidence has been gathered throughout the years; references to the possibility of a "Thomas, Jr.," a firstborn son that died as an infant, usually from a brain injury, go way back through decades of Batman comics. The theory suggests that Thomas Jr. was stolen at an early age, presumed dead, and spent much of his early life suffering from locked-in syndrome as a result of his brain injury. He was either kidnapped or kept in a crooked hospital throughout all of his early life, explaining why he has no fingerprints on file. There are a number of villains who have tried to get to Batman by pretending to be his lost loved ones, and this theory implicates the Joker as the one pulling the strings, using these pawns to drop hints to his brother, hoping that Batman will one day uncover who he really is. One argument is that the Caped Crusader actually knows Joker's true identity, subconsciously, and that's why he's never allowed the Joker to die.

Some have even suggested that there are hints of this theory sprinkled into The Dark Knight, which is where Joker so lovingly speaks of the parallels between him and Batman. But hey, speaking of The Dark Knight...

6. The Dark Knight - How DID He Get Those Scars?

Heath Ledger and Maggie Gyllenhaal in The Dark Knight

Back when Heath Ledger was first cast as the Joker in Christopher Nolan's then- Batman Begins sequel, no one could have ever foreseen that he would become arguably the most iconic version of the villain to date. Ditching the perma-white skin and chemical bath for powdery makeup and a Glasgow smile, Ledger's Joker was a living embodiment of chaos, a philosophical serial killer who was every bit Batman's equal. And like the comic book character before him, this Joker came out of nowhere, but liked teasing his victims with false stories about his identity: "Wanna know how I got these scars?"

In the film, the Joker offers at least two explanations, both of which may be false. In one, he claims to have once had a wife, whose face was cut up by loan sharks; in order to show her that he didn't care about the scars, he says, he cut his own cheeks up. This story, of course, is a callback to The Killing Joke. At another point in the movie, though, the Joker claims that his scars are from the knife of his father, whom he claims was "a drinker... and a fiend." At the end, Joker is about to tell Batman a third, probably altogether different story, but the Dark Knight cuts him off.

One thing that does seem for sure is that the Joker probably did have issues with his father, since there's at least one other instance of him lashing out at another character who reminds him of his old man. One theory hypothesizes that Joker may have been a war veteran with PTSD, explaining his comfort with and access to all that military-grade weaponry. Other theories suggest he may be an escapee from Arkham Asylum, a former circus worker, or an incarnation of the devil.