Harley Quinn (Arkham Series)

Harleen Quinzel, former psychiatrist and 'girlfriend' of the Joker. A trained gymnast and deadly with a hammer, Harley (as she now calls herself) is a menace to Gotham with or without her, "Mistah J." During the events of Arkham Asylum and City she was at his side partaking in the mayhem as always, but was dealt a terrible blow when complications from Joker's Titan sickness led to his death.