Batman fans divided as Dark Knight's Joker origin seemingly revealed

Spoilers for Joker: Folie à Deux follow, read on at your own risk.

In 1988's classic, if controversial, graphic novel Batman: The Killing Joke, Joker admits if he has a past he'd much rather it be multiple choice.

This, for many, has proved such a huge part of Joker's appeal over the years. Both as a Batman villain and a character in his own right.

Where Joker comes from, who he is and what he wants - these are things we're never supposed to understand. This mystery was a key part of Heath Ledger's celebrated portrayal in The Dark Knight, of course.

You can understand, then, why so many Batman fans are getting pretty upset over the idea that Heath Ledger's Joker now has a definitive origin.

Joker: Folie à Deux, which came out last week, hasn't exactly been a hit with critics or fans. The musical elements have left many fans cold, but it's the ending which has proven to be most divisive. Again, spoilers to follow.

The long and short of it is that the Joker sequel ends with Arthur Fleck (Joaquin Phoenix) effectively renouncing the Joker persona and serving his time in Arkham.

Unfortunately, things take a dark turn when Arthur is stabbed to death by a fellow inmate. An inmate who can seen in the background as Arthur bleeds out carving a smile into his face with the same weapon he used to kill Arthur.

While it's still open to interpretation, a lot of fans have taken this ending to mean we're supposed to believe the inmate who killed Arthur is in fact Heath Ledger's Joker, and that the two Joker movies were his origin story all along.

Over on Reddit fans have rightfully pointed out there are multiple reasons these two universes can't be the same, but the mere implication that they ever could be has left fans reeling.

"I don't like the implication that the person who killed him is the Heath Ledger Joker," one fan wrote. "That is just dumb and kinda insulting."

Another argued: "Agreed , but I think the ending was attempting to portray the idea that anyone can be the joker, not necessarily 'the heath ledger joker'."