Fan Casting James Powell in Jon Favreau's John Carter of Mars

The man who was once John Carter's closest friend, Powell arrived on Mars a century before Carter and became the Desert Prophet Sab Than, convinced that only he can save the dying planet. Charming and idealistic at first—a man of action who genuinely believes he is helping—before revealing the cold, genocidal despot beneath. His betrayal is made all the more tragic because we understand his pain. He is the film's most complex character: a villain who could have been a hero.