Alan Moore had created an original variation of the Joker and came up with a unique way to explain why such a character could be unkillable. This, of course, is the villain Painted Doll from the sci-fi/supernatural series Promethea. The book came out in the early 2000s and was produced by JH Williams III and Mick Gray along with Moore.
Although the series’ titular character is magic-based, the story did feature a Fantastic Four parody called the Five Swell Guys. They were called science heroes instead of superheroes and their nemesis was a clown-looking serial killer named the Painted Doll. The character was obviously heavily inspired by the Joker and shared the Clown Prince of Crime’s tendency to come back from the dead. No matter how many times the Painted Doll was defeated and killed he always came back scarier than ever.
Eventually, it was revealed that the Painted Doll wasn’t just one person. It was actually a series of artificial creations hidden under a lake, and a new one was activated whenever the current one was destroyed. Even more shocking was that it was a member of the Five Swell Guys who was behind the entire plot. He did this to get revenge on the team’s leader. Eventually, all of the Painted Dolls turned on each other, driven by the thrill of killing something exactly like them. Interestingly though, the last remaining doll develops its own personality after Promethea intervenes. This Painted Doll later takes the place of its creator in the Five Swell Guys.
Alan Moore isn’t really suggesting that the Joker is a series of robots that keep coming back from the dead. (The closest DC Comics comes to that conclusion was the revelation that there were actually multiple Jokers at work.) Instead, the Painted Doll is merely a Joker-inspired character. Moore uses him as a satirical explanation for how the Joker can keep coming back regardless of how many times he’s been shot, stabbed, beaten, and blown up.
The in-continuity explanation for the Joker’s immortality is either chalked up to luck or Batman’s unwillingness to kill him, which is somewhat necessary as it forms Batman’s (aka the Caped Crusader) moral backbone. And Joker, being the psychopath he is, doesn’t necessarily care for his own life. Ironically, DC Comics does, though. The explanation for why Joker keeps coming back is simple: he’s a popular character and DC doesn’t want him to die. Moore obviously had fun with this notion in his own title, where he had the freedom to play around with the Joker archetype in a way he wouldn’t be able to with the actual character.
