Collider reports that the actress who broke through in 'The Wolf of Wall Street' will play Harley Quinn, the Joker's girlfriend and henchwoman, in the forthcoming Warner and DC Comics feature.
Her supervillain companion might be played by Jared Leto, according to The Wrap.
Harley Quinn first appeared in 'Batman: The Animated Series' and went on to become one of the most popular secondary characters in the Dark Knight's universe.
Once a psychiatrist attempting to analyze the Joker at Arkham Asylum, she was manipulated by the supervillain into becoming his girlfriend and accomplice.
Just after Collider reported that Margot Robbie would play the female villain in 'Suicide Squad', The Wrap reported that Jared Leto might be circling the role of the Joker.
Ryan Gosling was previously eyed to play Batman's arch enemy before he refused to sign a contract with sequel options, often a sine qua non for major studio franchises.
Joaquin Phoenix turned down Marvel's invitation to play Dr. Strange on the silver screen for the same reason.
Among the other actors in the running to play the green-haired villain in 'Suicide Squad' are Tom Hardy and Will Smith.
A few weeks ago, rumors indicated that supermodel Cara Delevingne might also play a member of the supervillain team. No official casting details have been announced so far.
Based on the DC Comics of the same name, 'Suicide Squad' will center on a league of incarcerated supervillains who, in exchange for reduced sentences, undertake life-threatening missions for the US government.
To be directed by David Ayer, the film is due in theaters in 2016.