Gotham Season 3: Who Is Dr. Quinzel?

Erin Richards as Barbara Kean
Possibly Harley Quinn

Harleen Francis Quinzel happnes to be a supervillain in the DC Universe and usually appears as a foe of Batman. Throughout her appearance in the comics she was associated with several villainous organizations. She is also a member of the Suicide Squad formed by Amanda Waller, head of A.R.G.U.S..

Harley initially appeared as a sidekick to the Joker, but later on in the comics came to be known as his accomplice and lover.

Harleen Quinzel, M.D. is an Arkham Asylum psychiatrist who falls for the Joker and becomes his accomplice and sidekick.

Her fascination with the Joker starts while working in the Asylum so she volunteers to help treat him. Falling helplessly in love with him during their sessions, she helps him escape the asylum more than once. The sight of him badly injured when Batman returns him to the Asylum drives the young psychiatrist insane leading her to quit her job and adopt a jester costume becoming Harley Quinn, the Joker's sidekick. She then befriends Poison Ivy who injects her with an antitoxin increasing her agility, strength and immunity to toxins.

Worth noting here that one of the executive producers of FOX's TV series Gotham has hinted that Harley Quinn might already exist within the series and that the viewers might just not know she is who she really is yet. Suspicions go to the only character who could possibly still get a clear villainous persona, Barbara Kean (Erin Richards).

Leslie Thompkins (Morena Baccarin) can also be used on the series in the same capacity especially given the fact she is a psychiatrist. However, that will require a complete deviation from who she is in the comics.

Gotham returns to FOX this fall with all new episodes for its third season.