Originally, Batman: Arkham Asylum was to be Mark Hamill's last performance as the Joker, as he wanted to leave on a 'high note'. However, after hearing that writer Paul Dini would return to write the sequel, and that Kevin Conroy would reprise his role as Batman, Hamill agreed to play the role one last time.

Spoiler:He would once more reprise the role for the hallucination scenes in Batman: Arkham Knight.
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