Harley Quinn's middle name is Frances, as her real name is Harleen Frances Quinzel.
Harley Quinn first appeared on Batman: The Animated Series in the episode, "The Jokers Favor". She was created by Paul Dini and Bruce Timm and inspired by Arleen Sorkin and one of her characters Harlequin. Harleen Quinzel was a former Pyschiatrist at Arkham Asylum.
Her patient was the Joker and he told her all his "secrets" and eventually she fell in love with the Clown Prince of Crime. Harleen Quinzel adopted the name Harley Quinn and broke the Joker out of the Asylum and became his assistant.
Through all of her comedic and endearingly psychotic moments, Harley Quinn’s story is tragic and — although extremely heightened — relatable for many people. Here's everything you need to know about Harley Quinn, from Breakout Batman Villain to ‘Súicide Squad’ shared by Screenrush.com.