Sephiroth is your God! Kneel beofre him! He is THE MOST POWERFUL villian in the history of...well...villians. He originated from final fantasy VII. To answer intelligently: Sephiroth first debuted in Final Fantasy VII as the game's main antagonist. A former renowned hero gone insane over the origins of his birth, he goes on a vendetta against mankind. In Kingdom Hearts, Sephiroth is the physical embodiment Cloud's darkness.