Charles zi Britannia (シャルル・ジ・ブリタニア ,Sharuru ji Buritania?) at first only referred to as The Emperor of Britannia (ブリタニア皇帝 ,Buritania Kōtei?), born October 15, 1955 a.t.b.,[9] is Lelouch's father and the 98th Emperor of the Holy Britannian Empire.[10] A strong proponent of Social Darwinism, he views equality as an evil that must be dispelled, and to this end he encourages class conflict and military expansionism so as to maintain social evolution and progress. He has 108 different consorts.

Charles is willing to use his children to accomplish his goals, such as sending Lelouch and Nunnally to Japan as political hostages during the sakuradite conflict. He also installs his children in important positions throughout the Empire to test their abilities. Charles intends to invoke Ragnarök, remaking the world into a place without lies. This is done with the Sword of Akasha, a weapon designed to kill "God", which in Code Geass is the collective unconsciousness of all mankind. Lelouch sees Charles' ideal world to be nothing more than stagnation that would doom mankind rather than save it, and he uses his Geass to turn the collective unconsciousness on his father, resulting in his and Marianne's deaths. Just before his death, Charles warns Lelouch that Schneizel's world will be the one that awaits him.

The Emperor initially possesses a Geass power given to him by V.V. which allows him to suppress memories and create false ones through eye contact. It can also suppress the Geass power of the target, even if it is permanently active. During Lelouch's assault on the Geass Order, he takes on V.V.'s "Code," exchanging his Geass for immortality. The Code mark is situated on his right palm.

Source: Wikipedia