The Joker is such a reliably entertaining villain for Batman that he's rarely killed: he normally lives on to fight again another day, though in Rocksteady's Batman: Arkham City, the Clown Prince of Crime's luck finally ran out. It turns out that the Titan formula Jokes overdosed on in Arkham Asylum is slowly killing him, and right at the end of the game, Batman considers using the antidote on him, but before he can decide, The Joker attacks him, causing the vial to smash, ruining any chance of him surviving the formula's effects. The game concludes with The Joker dying, and Batman carrying him out of Arkham City, much to the shock of his cronies outside. Commissioner Gordon quizzes Batman about the incident, but he simply dumps Jokes' body on a cop car and leaves. It's a turning point for the Arkham video game series: given how crucial a component The Joker is, for him to be unable to appear in the upcoming Arkham Knight is a pretty brave move on the part of Rocksteady. Can they make Scarecrow as viable a threat as the Caped Crusader's most iconic ally? We'll have to wait and see...