This article contains spoilers for Batman/Catwoman #3 by Tom King and Clay Mann.
The Joker is destined to be killed by Catwoman, not by Batman. The Joker has always delighted in pushing Batman to the brink. No other villain has wrought such chaos in Gotham City, and the Joker's attacks have frequently proved very personal indeed for the Dark Knight. That was certainly the case in the Joker War, when the Clown Prince of Crime even managed to steal the Wayne fortune and use it to fund his own criminal enterprises.
But the Joker has always imagined his greatest triumph would be the moment when he truly broke the Batman – when he pushed Bruce Wayne so far he forgot his moral code and killed the Joker in a moment of fury. To the Joker, such a death would indicate he had been proved right; that he had demonstrated once and for all the only thing separating him and Batman was one bad day.
Tom King and Clay Mann's Batman/Catwoman #3 reveals the Joker will never win – because Catwoman is the one destined to kill him, not Batman. The comic is set in a future timeline in which Bruce and Selina Kyle have lived a long and happy life together, and their daughter has taken over the mantle of the Bat. Bruce has recently passed away, and his daughter is contacted by Commissioner Grayson – the future Nightwing – with news that a body has been found in a retirement community in Florida. His throat was slashed ear to ear, and upon examination, police officers realized he was wearing makeup to conceal bleached white skin. The Joker had finally been found – murdered shortly after Batman's death.
Of course, readers know more than Batwoman does. The previous issue saw the elderly Catwoman visit the Joker in his retirement community, confronting him and initially reminiscing about old times. It wasn't long before the Joker drew a gun, in a last desperate attempt to fight for his life. His efforts were doomed to fail because while he had diminished Selina had remained at peak physical health for her age. Catwoman slashed his throat, an act of revenge for all the Joker had cost her over the years – one that had only been delayed because of Bruce Wayne.
There is a tragedy to this tale, though. When he passed away, Batman knew his death could unleash a vengeful Catwoman upon the world, and he had Selina promise not to misbehave. It seems that is one promise she does not intend to keep – and it remains to be seen whether Batman's daughter will be the one to bring in her own mother. Perhaps the Joker will have the last laugh in a sense after all.