Before her descent into madness, Dr. Harleen Quinzel was a promising psychiatrist assigned to Arkham Asylum, Gotham's home for the criminally insane. But after meeting the Joker, the young doctor became obsessed with the crazed criminal's warped mind. Sensing opportunity, the Joker manipulated her, driving his therapist so mad that he was able to control her. Harleen fell in love with the villain, broke him out of Arkham and devoted her life to making him happy and spreading his bloody brand of mayhem.

Harley Quinn