(SPOILER)I actually feel a bit sorry for Sephiroth. He winds up being driven mad by his father, who has been totally crazy for a good few decades (and whom I really hate). Sephiroth thinks that he is the last remaining Cetra (besides Aeris), and that therefore he will rightfully inherit the world and destroy the pitiful creatures who stole it from his mother. The truth is that he was the child of Hojo and Lucrecia, with Jenova cells added to his genetic makeup. Even if he had been Jenova's son, he wouldn't have been the last (again, other than Aeris) of the Ancients, because Jenova was not an Ancient. This is quite clearly stated in the game (I can't give you the exact quote right now, but I will as soon as possible). Not only was Jenova not an Ancient, but he/she/it was an object of fear for the Ancients. Jenova, the calamity from the sky... I still wonder what would have happened if Sephiroth had learned the truth (say, from Professor Gast), instead of getting the twisted version of things that was the way Hojo saw the events. First he is deceived about his true family, then he stumbles upon Hojo's monster making project... What would have happened if he knew the truth? I think he could've been an awesome good guy. As it is, he became one of the most incredible RPG villains in existance. Sephiroth is always doing what he believes is right. Yes, he is insane to the point that he thinks that the right thing to do is to make himself a god, but it's still what he believes is right. He's not simply an insane villain. He's an insane villain who stands by his principles (however warped, twisted, insane, deluded, etc... they may be). I think this is a major point in his favor. Villains are all too often either insane to the point that they don't care what they're doing, or they are purposely being evil. Sephiroth is totally insane, but he does care about what he's doing. He's dishing out a heaping helping of Apocalyptic justice, and reclaiming his rightful place in the world as he's doing so. It's sad that he never learned who his real family was, or how he really came to be. He is a great character, in my humble opinion.
...Oh, yes, a couple things more. He dresses all in black, wears long white hair in such a way that it looks cool, and has a sword that can be used for pole-vaulting. Those (combined with my previous points) should be enough to firmly place him in the "RPG Villain Hall of Fame".
