10 Times The Joker Basically Defeated Himself

In the climax of Rocksteady's Batman: Arkham Asylum, the Joker injects himself with a drug called Titan, turning himself into a monstrous brute. Although he is inevitably defeated by Gotham's protector, the Joker is far from finished.

In the sequel, Batman: Arkham City, the Joker learns Titan has mutated his blood, infecting him with a fatal disease. Refusing to go down without a fight, the Joker injects Batman with his tainted blood, forcing the Dark Knight to find a cure, otherwise he'll die as well.

In the end, Batman tracks down an antidote and drinks a sample of it, returning his health to normal. Assuming Bats won't share the rest of the cure, the Joker leaps onto his back to grab the vial.

In the struggle, Batman accidentally drops the antidote, causing it to smash onto the ground, ending any chance the Joker had at saving his own life. Batman then tells his oldest rival that he was still going to help him, even after all the evil he had committed over the years, and just after he killed Talia right in front of him.

Acknowledging the irony of the situation, the Joker lets out one final cackle before dying.