Sephiroth

Sephiroth is the main antagonist of Final Fantasy VII and Final Fantasy VII Remake and one of the primary antagonists in its extended universe. In spin-off appearances, Sephiroth is depicted as Cloud Strife's archenemy and is seen as a symbol of Cloud's troubled past haunting him. Sephiroth is a former renowned SOLDIER who became twisted.
Before his fall from grace, Sephiroth was one of the most lauded success stories of the Shinra Electric Power Company's SOLDIER program. His successes in the field of battle during the conflicts surrounding Shinra's bid for global domination led to his status as a celebrity war hero and the poster boy for both the Shinra Military and the company's SOLDIER program. Learning of his true origins made him insane, causing him to be driven by a desire to destroy the world.
Sephiroth is briefly a party member during a flashback in the original Final Fantasy VII, and is both the penultimate and final boss.