Ahh, this entry is something else. Kefka! If you've ever heard that name before, then you know what game I'm talking about, and how insane this next post is. In Final Fantasy 6, this guy not only kills multiple people close to you, as well as other atrocities, but he manages to absorb the source of magic to an entire planet. By doing this, he is able to literally become a god, and literally destroy the planet. Killing most of the population, and turning it into something similar to a barren wasteland. My kudos go out to this guy, as he is one of the few villains that actually succeed in what they are trying to do. This maniacal, clown like god is one of my favorite antagonists in a game. His final boss fight is also an amazing tune, with a fitting name. "Dancing Mad"
http://www.youtube.com/watch?v=036i7mxg5BU