kuja
The main villain of Final Fantasy IX, Kuja is an androgynous sorcerer who reveals himself to be a cruel manipulator and an more extreme narcissist, and he is responsible for the majority of the game's events.
Major spoilers
He is responsible for manipulating Brahne to go to war; extracting Garnet's eidolons and attempting to extract Eiko's eidolons; creating the Black Mages to use as killer soldiers, and verbally tortures Vivi about it; causing the events that led to Alexandria's destruction (and inadvertently making Garnet lose her voice); betraying Garland; destroying the planet Terra; and then threatening to destroy Gaia when he discovers he doesn't have long to live. As a Genome given a soul by Garland, Kuja can be considered the older brother of Zidane and Mikoto.