2. Doctor Strange
With Loki still alive (and unpredictable) and the likes of Malekith the Accursed set to be introduced, the forces of good in the Marvel cinematic universe could really do with a powerful and competent sorcerer on their side in order to fight magic with magic if need be. That is where Doctor Strange might come in. Set to be the star of his own movie in Phase 3 (or beyond) of the Marvel cinematic universe, Stephen Strange is a human who masters the mystic arts to become this dimension's 'Sorcerer Supreme' - a title given only the very best magic users. Even if he only appears in a cameo, his help against the forces of Malekith would not be unwelcome and could serve as an ideal way to introduce a character who is set to become a massive part of the big screen Avengers team in their future endeavours.