Harley Quinn
An unhinged young psychiatrist that went mad when she tried to psychoanalyze the Joker. She became his girlfriend before she finally overcame his abuse and became a noted villain in her own right.
Where is she from?
Harley is an incredibly popular character from DC Comics Batman books. She's had several live-action appearances in different media, and we can explore some of them here:
Comic Appearances
GND 038 - Sarah tries on a Harley Quinn costume that Claire Bennet loaned her for the Halloween party, but Christine points out what a bad idea that is, frustrating a spying Jareth.