15 Actors Who Were Almost Cast as Your Favorite Avengers

Like Hiddleston, Rockwell initially was considered for one of the marquee Avengers roles, but instead made his Marvel debut as a villain — in his case, as Iron Man 2's slimy Justin Hammer.

"At one point, Jon [Favreau] had called me about possibility screen-testing for the part of Tony Stark in Iron Man. And whatever happened, I think I was out of the running. Robert [Downey Jr.] just killed it, you know, and I never heard anything after that," Rockwell told The A.V. Club. "So in a way, I think Jon was basically saying, 'This [playing Hammer] is your chance to be Tony Stark. This will be your version of Tony Stark.' We gave him the glasses and kind of sleazed him up a little. But that's exactly right. It was a chance to do Tony Stark."