1. Metallo
From my point of view, Metallo is the most likely choice for a Man of Steel sequel. It is not hard to imagine that the military, still not completely okay with a super-powered alien running amok on Earth, would be experimenting with ways to combat Superman if the need arose. In DC Comics' new 52 (also an inspiration for Man of Steel), John Corben is a military man. All it would take is a little Kryptonite (try not to cringe. This is really two movies away) and an experimental exoskeleton and BAM! Sure, this list is just me counting my eggs before they hatch. But I truly believe that Man of Steel will be the start of the definitive Superman franchise for our generation. So why not dream about what lies ahead?