While many comics, movies, TV shows and films have covered Batman's origin story, not many projects have tried to explain the circumstances that birthed the Joker.
Of course, Todd Phillips' Oscar-nominated 2019 film Joker made the attempt, and many years before that The Batman: The Animated Series movie Batman: Mask of the Phantasm took a stab at it as well.
However, for most comic book readers, The Killing Joke graphic novel by Alan Moore and illustrator Brian Bolland is considered the definitive origin story for Gotham's Clown Prince of Crime.
Recently, there's been a new wrinkle in the Joker's origin, thanks to Geoff Johns' Batman: Three Jokers miniseries, which proposed that there wasn't one Joker running around Gotham but three.
That 2020 miniseries concluded with a ton of questions left unanswered but Chip Zdarsky is attempting to tie up loose ends in his current Batman run. The current arc is proposing that the 3 Jokers are simply distinct personalities- the Clown, the Demon and the Killer.
Furthermore, the story proposes that the Joker crafted these personalities with the help of Batman's mentor, Daniel Captio, the man who taught Bruce how to create alternate personas like the Batman of Zur-En-Arrh.
Recently, DC Studios co-chair James Gunn was asked to weigh in on what he considers to be the definitive origin story of the Joker. [via Threads]
He stated, "I consider whatever I’m reading “true” in the moment I’m reading it! As for canon, I’m not in charge of mainstream DC Comics continuity - just that of the DCU (which will intersect & sway away & intersect again etc with DC Comics). These characters are all myths & I really enjoy the variations on them - especially when the artists understand the core of what I believe makes a character great & understands their history while offering a new spin."
In a follow-up response to another fan who stated that fans focus too much on what's canon, James stated [also via Threads], "So true. At least half of the top ten greatest DC stories aren’t canon."
Aside from Todd Phillips' Joker: Folie à Deux, which will hit theaters on October 4, 2024, there's no word on where or when the Joker will turn up next. Matt Reeves cast Barry Keoghan as Batman's #1 archrival in The Batman and it's thought that he'll play an expanded role in the sequel, which is slated for release on October 3, 2025.
With Damian Wayne set to take center stage in The Brave and the Bold, it's heavily speculated (but unconfirmed) that his grandfather Ra's al Ghul, mother Talia and the League of Assassins will serve as the DCU Batman's first/primary antagonist.