The Joker is the main antagonist of Batman: Arkham Asylum.
At the beginning of the game, Batman captures the Joker and escorts him to Arkham Asylum, but the arrest is part of the villain’s plan. The Joker escapes, takes control of the facility with help from Harley Quinn and corrupt staff, and releases dangerous inmates across Arkham Island.
His larger scheme involves the Titan formula, an experimental substance derived from Bane’s Venom. The Joker intends to create enhanced soldiers and ultimately uses the formula on himself, leading to the game’s climactic confrontation with Batman. His plot drives the main story even though Batman battles several other villains along the way.
Scarecrow is responsible for some of the game’s most memorable fear-toxin sequences, while Riddler provides collectible puzzles and challenges. Two-Face does not serve as the central villain in this installment. The Joker was voiced by Mark Hamill, with Kevin Conroy returning as Batman, a pairing strongly associated with the earlier animated Batman series.