2. Benedict Cumberbatch - Avengers: Age Of Ultron
It's already confirmed that Tom Hiddleston and Idris Elba will be making some sort of cameo in Avengers: Age Of Ultron, but they are already established characters and they'll probably only appear in one of the visions that Scarlet Witch causes Thor to have. Therefore, it would be cool to have a cameo from a character who has previously not been introduced in order to continue the trend of expansion in the Marvel Cinematic Universe and, in this particular case, ease fans into the idea of actual magic being introduced into the franchise. Benedict Cumberbatch should, therefore, make his first appearance as Doctor Strange. Whether it's in the main body of the movie or a mid/post-credits scene, it would certainly make sense to introduce magic as a concept prior to his solo debut. Various hints in the trailer point towards the character (surgical equipment, a large mansion-like refuge atop a mountain etc) and Cumberbatch was cast just prior to some additional filming taking place on this movie, so it could happen. And obviously there'll be a Stan Lee cameo in this one too.