Rita Ora as Mia Grey
Singer and actress Rita Ora revealed via Twitter that she'll be playing Christian Grey's sister, Mia. "It's official! I've been cast in @FiftyShades of Grey as Christian's sister Mia. #FiftyShades," she posted.
In the novel Fifty Shades of Grey, Mia is depicted as an outgoing person who has a crush on Ethan Kavanagh, her brother Elliot's brother-in-law.