6. Armie Hammer
Why? He's young, he's handsome and he's a real physical presence in the Golden Age tradition of leading men, and would bring something to the role of that sort of era, which would be an interesting way to add depth to the character. Grey needs to be immediately charming, disarming and have good presence, and Armie's look, as well as his ability to play slightly alouf characters would make him a good match to that side of the role. The reservations surrounding Hammer would be that he might appear a little too vanilla for the role, but then critics had similar reservations concerning Heath Ledger ahead of his astonishing performance as the Joker in the Dark Knight, and Hammer could be a surprise. He certainly has a good look for Christian Grey, especially in terms of his business man "day face", and the sort of physical presence that just might translate into that necessary animal attraction and sexual power.