Which villain supposedly dies in Batman: Arkham City?

The Joker supposedly dies in Batman: Arkham City. He is already suffering from a fatal illness caused by the unstable Titan formula, a dangerous substance derived from Bane’s Venom.

During the game, the Joker infects Batman with his diseased blood and also contaminates blood supplies in Gotham hospitals. Batman searches for a cure, eventually obtaining an antidote connected to Mr. Freeze and Ra’s al Ghul. However, the cure is destroyed during the final confrontation when the Joker attacks Batman, leaving Batman infected but alive.

The Joker then finally succumbs to the illness. Batman carries his body out of the Monarch Theater and places it on Commissioner Gordon’s car, creating one of the series’ most memorable endings. The apparent contradiction is that the Joker still appears in Batman: Arkham Knight. Those later appearances are hallucinations and manifestations caused by the Joker’s blood and Batman’s psychological struggle, not evidence that the original Joker survived Arkham City.