the main boss character in Final Fantasy 7
Sephiroth is one of the central antagonists in the Compilation of Final Fantasy VII. One of the most popular villains in the series next to neighboring villain, Kefka Palazzo of Final Fantasy VI, Sephiroth has appeared in every installation of the Compilation in some form or another. Sephiroth is the son of Lucrecia Crescent and the late Professor Hojo, part of the grand experiment known as Project S to create the ultimate super soldier by using the salvaged cells of the alien Jenova. Wielding a ridiculously long sword known as the Masamune combined with his master swordsmanship, Sephiroth reaps his enemies with impunity. Before his villainous days, Sephiroth was once revered as a hero, the top of the elite ShinRa troop known as SOLDIER. Despite his aloof attitude, he was not without friends, the son of Gillian Hewley, Angeal Hewley and the original wielder of the Buster Sword. The other was Genesis Rhapsodos. He later on finds a friend in Zack Fair. His fall to insanity was due to Genesis telling him about the truth by his existence, albeit a slightly distorted one. Due to incomplete information, Jenova was thought to be one of the Ancients that inhabited the planet, and eventually calls the half dead alien his 'mother', a monster. Setting aflame the town of Nibelheim, Sephiroth had upset quite a few pivotal characters out for him, most notably of all, his counterpart-to-be-, Cloud Strife, whom idolized him. He had run Sephiroth through with Zack's Buster Sword and even managed to 'kill' him, avenging the death of his mother as well as saving Zack and Tifa.
Since his fusion with Jenova and incubation in the Northern Crater, Sephiroth began to grow in power. Through the power of the Jenova cells infused in Cloud, Sephiroth would begin to torment and brainwash Cloud into doing his bidding. Ever since the aftermath of FFVII, Sephiroth has remained as a lingering shadow within Cloud, a repeating phantasm constantly promising despair and suffering to the man who killed him twice.