10. Skull Man – Mega Man 4
There are a lot of robot masters in the Mega Man series, but Skull Man is certainly one of the coolest looking. Not only does he have an awesome theme song and stage, but his ability to use giant skulls as a barrier only makes him more badass. Plus, the references to skeletons throughout his level really gives his world some flavor, to the point where one has to wonder who builds a stage out of bones? Even though he is not a terribly difficult boss to defeat, his overall design and fight is a great introduction for Mega Man 4.