The Joker (Bianca Steeplechase)

Bianca Steeplechase was a ruthless gangster also known as the Joker. During the dynamic duo's final case, Bianca framed Bruce Wayne for the murder of Selina Kyle, and killed Robin with a fatal kiss (tongue was dabbed with poison). With Bruce on the run from the law, and Barbara in desperate need of a partner before she goes on the verge of a mental breakdown, they become a team, with Bruce donning the bat mantle. As for Bianca Steeplechase, she's dead. All there's left is Mrs. Gregory Wilson, the new wife of the mayor.