8. Matthew McConnaughey
Why? Well, based on his performance in Magic Mike, McConnaughey has the body for sex scenes, and he's certainly caught a lot of female eyes since he first appeared in Dazed and Confused. Mr Grey would certainly fit in with McConnaughey's recent career choices, as he seems intent on reinventing himself as a darker, more interesting figure than the go-to guy for rom-coms and taking his shirt off.
McConnaughey might not fit the suggested appearance of Christian Grey quite as closely as other suggestions here, and he is certainly a little on the old side, but he has that essence, and that physical energy that would make him an ideal candidate, if an outside one. He has also proved recently that taking off more than his shirt doesn't seem to be an issue, thanks to a near-nude showing in Magic Mike, which also channelled both the actor's innate charisma and his capacity to play difficult characters well.