The Social Network star beat the likes of Carey Mulligan and Scarlett Johansson to play young computer hacker Lisbeth Salander in the highly-anticipated Hollywood adaptation of Stieg Larsson's The Millennium Trilogy.
And while newcomer Mara was thrilled to be cast in the David Fincher film, she confesses she nearly snubbed the movie because of the huge fame which will come as part of the package.
She tells America's Vogue magazine, "That kind of fame is not something I ever wanted for myself. It just so happens that this huge, gigantic monster of a film came around that also happens to have the most incredible character that I ever could have dreamed up.
"But my fear with a movie like this is the kind of exposure you get from it. I think that can be death to an actor. The more people know about you, the less they can project who you are supposed to be. It's unfortunate that you really only get one shot at that. After this, I won't be able to be that girl again."