Harley Quinn is a character created for the show Batman: The Animated Series. She first appears in the episode "Joker's Favor" and has frequently appeared ever since. She began as Joker's moll and then retconned to be his former psychiatrist at Arkham Asylum. Quinn eventually become a well known Gotham criminal in her own right, frequently working with Poison Ivy on crime sprees. (Under construction might make multiple characters cuz of Harleys design)