Harley Quinn

FIRST APPEARANCE: Joker's Favor (Batman: The Animated Series Season 1, Episode 7; September 11, 1992)
FIRST COMICS APPEARANCE: The Batman Adventures #12 (October 1993)

Like almost everything about her, Harley Quinn’s origin story is constantly changing and evolving. The first time it was told, she was revealed as a brilliant psychologist employed by Arkham Asylum. Dr. Harleen Quinzel, by all accounts, was on the path to a bright and promising future. But her interest in criminal psychology had insidious roots. While she was studying, her professor, Dr. Odin Markus, manipulated Harleen into believing chaos is the only true constant in the world. Markus went so far as to orchestrate a scheme in which Harleen was made to puppeteer her own boyfriend, a man named Guy Kopski, into committing murder on her behalf.