6. Harley Quinn
Who She Is: A frequent accomplice of the Joker, sometime ally of Poison Ivy, and sometimes alone, Harley Quinn is always surprisingly dangerous. She began as an intern at Arkham Asylum, but becomes fascinated by the Joker, and asks if she can analyze him. Instead, she eventually falls in love with him and becomes his sidekick.
Special Powers/Skills: She has an immunity to many toxins and forms of poison, thanks to her friendship with Poison Ivy. She also has very good agility and strength, as well as having been trained in numerous martial arts forms.
Who Should Portray Her: Emily Browning, seen in Lemony Snicket's A Series of Unfortunate Events, and more recently in Zack Snyder's Sucker Punch.