12. ROONEY MARA

The daughter of one of the bosses behind the New York Giants franchise went from being an unknown, relatively indistinguishable actress to adopting the darker look of the role that will make her a superstar, Lisbeth Salander in the American remake of The Girl with the Dragon Tattoo. With her newfound persona, mysterious confidence,and undeniable talent, Mara has become one of the most desired casting choices in Hollywood. Kathryn Bigelow and Terrence Mallick are already recruiting her for their new films.