Since the events of Suicide Squad, Harley Quinn has left the Joker. When Roman Sionis, a narcissistic crime lord known as Black Mask, places a hit on a young girl named Cassandra Cain, Gotham City turns upside down looking for her. Harley joins forces with Black Canary, Helena Bertinelli, and Renee Montoya to protect the girl and to take Sionis down.
Margot Robbie as Harleen Quinzel / Harley Quinn:
A former crazed criminal turned vigilante who is part of the Suicide Squad and a former psychiatrist. Screenwriter Christina Hodson sought to reinvent Harley, wanting to expand on the character following her departure from the Joker. Hodson called Harley the character she enjoyed developing most due to her unpredictable personality.
Mary Elizabeth Winstead as Helena Bertinelli / Huntress:
A vigilante and the daughter of mafia syndicate gangster Franco Bertinelli.
Jurnee Smollett-Bell as Dinah Lance / Black Canary
Rosie Perez as Renee Montoya
Chris Messina as Victor Zsasz:
A deranged serial killer who carves a tally mark on his skin for each victim he claims.
Ella Jay Basco as Cassandra Cain:
A young girl who is threatened by Black Mask.
Ewan McGregor as Roman Sionis / Black Mask: