Charles zi Britannia is the main antagonist of the series, though his role is minimal compared to that of his children. He is voiced by Norio Wakamoto (Japanese), and by Michael McConnohie (English).
Charles zi Britannia, 63 years old, is the 98th emperor of the Holy Britannian Empire and Lelouch Lamperouge's father. He has 108 consorts. He installs his children in important positions throughout the Empire to see their true abilities. which shows he has little care for their own lives since Clovis dies while being asigned as viceroy of Area 11.
A strong proponent of Social Darwinism, Charles views equality and justice as an evil that must be dispelled and encourages social battle to maintain evolution within society. As such, he publicly supports inequality and calls for competition and fighting, so as to create progress, even proclaiming the death of his son, Clovis La Britannia, as a demonstration of Britannia's unswerving commitment to progress. In the seventh episode of the second season, he reiterates his viewpoints by saying that the traditional morals of not murdering, not deceiving others, not stealing, and remaining faithful are lies used by the weak to defend themselves, and that survival of the fittest is the only truth, which he considers Britannia's duty to show the world. Despite openly supporting warfare, he views it as an ineffective tool compared to diplomacy and bargaining.
Charles' appearances in the first season are minimal. In a flashback, Lelouch questions why the Emperor did not try to protect his mother, Marianne Vi Britannia. Irritated and considering his son to be nothing without him, the Emperor sends both Lelouch and his sister, Nunnally, to Japan as political hostages.
He makes a number of short appearances throughout the season, displaying apparent knowledge of Lelouch's activities, particularly in relation to his Geass usage. He also claims to be speaking to Clovis after his death, though he may not have been speaking literally.
In another flashback in the second season, Lelouch is brought before the Emperor by Suzaku Kururugi. Suzaku requests a position within the Knights of the Round as a reward for capturing him, which the Emperor grants because he is impressed with Suzaku's willingness to sacrifice his friendship with Lelouch to begin his quest to change Britannia from within. He then uses his previously unknown Geass ability to rewrite Lelouch's memories and suppress his Geass power. He does the same to the students of Ashford Academy.
Because Suzaku is the only one of the Knight of Rounds who knows of Zero's identity and Geass, the Emperor trusts him enough to lead him to The Sword of Akasha, a temple above the clouds and skies designed as a weapon against the gods. C.C. suggests that V.V. is the one who granted Charles his Geass, though the specific nature of their alliance and contract is to destroy the gods. He is actually Charles's twin brother, whose aging has stopped at an early age due to his Code. General Bartley's earlier suspicions are partly correct, as the Emperor plans to use the Thought Elevators to unleash Ragnarök, which will destroy the collective human consciousness and reform them as a single consciousness.
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 Directorate, he takes on V.V.'s Code, exchanging his Geass for immortality. He now intends to unlease Ragnarok through all the Thought Elevators on the planet.
During the ceremony of the UFN and the preperations to liberate Japan from Britannia, Charles appears to Zero and the Black Knights declaring that the E.U. has finally collapsed and that the victor shall take control of the entire world, since the world is literally divided between the Holy Britannian Empire and the UFN. During the second battle of Tokyo, Charles is seen aboard his flagship approaching the coastline of Japan, much to the shock of Lelouch. Bartley's earlier suspicions are partly correct, as the Emperor plans to use the Thought Elevators (using the one in Kamine Island) in conjunction with the Sword of Akasha (damaged by Lelouch) to unleash Ragnarök. This is done with the Sword of Akasha, a weapon designed to kill "the gods", which in Code Geass is the collective unconsciousness for all of mankind. Lelouch sees this goal to be nothing more than stagnation that would doom mankind rather than save it, disrupts this plan by turning the the gods on his father, resulting in his and Marianne's destruction. Just before his death, Charles warns Lelouch that Schneizel's world will be the one that awaits him.
The Emperor of Britannia possesses the ability to freely alter an individual's memories at will; he may also seal the ability of another Geass user, as well as physical abilities such as eyesight. Geass sigils light up in both eyes when he uses it. The influence of this ability may be cancelled by C.C. This was given to him by V.V. During Lelouch's assault on the Geass Directorate, he takes on V.V.'s Code, exchanging his Geass for immortality. The Code mark is situated on his right palm.