Claim: Arkham Asylum's patients include the Joker, Two-Face, Poison Ivy, the Riddler, and Harley Quinn.
Evidence: Arkham 's high-profile patients are often from Batman 's rogues gallery , such as the Joker , Two-Face , Poison Ivy , the Riddler , Harley Quinn , Clayface , Mad Hatter , Killer Croc , Mr. Freeze , and Scarecrow.