I like Sephiroth as a character but not much as a crazy villain. He only has two moments of villainous that really sticks out even years after playing the game. Burning down Cloud's home in his anger and killing Aerith, the latter of which he did while she was defenseless in the middle of a prayer from behind. When you first start hearing about him I thought they were building him up as the anti-hero. Someone who was willing to go to extreme measures to make sure Shinra didn't harm another soul in response to the experiments and such. Since I always saw Shinra as the true villain of the verse since they're responsible for pretty much everything. But I digress.