Sienna Miller as The Baroness

Sienna Miller as The Baroness - G.I. Joe: The Rise of CobraSienna Miller as The Baroness: A spy and sister of Cobra Commander. Years before the film, The Baroness was going to marry Duke, but he left her at the altar, due to his guilt over the apparent death of her brother Rex Lewis.The Movie: G.I. Joe: The Rise of Cobra is a 2009 American live-action film adaptation of the G.I. Joe toy franchise