Sephirothセフィロス is the main antagonist in Final Fantasy VII.
Sephiroth has been created by Jenova cells and mako energy. He wields a Masamune, which only he can wield.
He was part of an elite army in Shinra called SOLDIER. Once he found out the terrible experiments that created him through notes at Nibelheinm he went insane and almost destroyed the planet. Using Aerith's life she used holy with the power of the life stream, she stopped meteor but Aerith dies after the use of the spell.
In final fantasy 7 advent children, Sephiroth comes back in the body of Kadaj by sacrificing Jenova's head. Cloud defeats him with the Fusion swords and spirits of his friends Zack and Aerith. He warns Cloud that he will never be a memory.