His real name is Lelouch vi Britannia. He is the eleventh prince of the empire of Britannia. His mother, Marianne vi Britannia was murdered when he was child. Then his younger sister Nunnally became blind and could not walk by herself. She needed a wheelchair. Therefore, he hated Britannia and decided to create the kind world where Nunnally can live safely. He obtained Geass from C.C. and leaded a group of terrorists he united as the Black Knights with his well-known identity as Zero towards his revenge against Britannia and to create a better world for Nunnally. He latter wields the Knightmare Gawain with C.C. and Shinkirō in R2.