User blog comment:Professor Ambrius/Doctor Strange Movie Villain/@comment-25592856-20141031192839

Mordo, Dormammu, and Nightmare all make sense. It would be interesting if the movie was less of an "I'm fighting the one big baddy" scenario, and we really got to see Strange stretch his magical muscle - in which case, additional foes like Shuma-Gorath, Umar, Satannish, or Mephisto could be part of the landscape. Perhaps the Fear Lords. There are some options from his own canon, even before borrowing from others.

That said, you're right - Strange's villain bench isn't very deep.