Master Chief is the main character in the Halo series. He wears a helmet in the game that has never been taken of of his head in any of the games, and he also is a Spartan in the Halo series. His real name is John. In Halo, you control Master Chief. He is usally on the cover of the Halo games. He is the protagonist and main playable character in Halo: Combat Evolved, Halo 2, Halo 3 and the upcoming new trilogy. In the games, John is only ever referred to by name once, by Cortana, in the ending cutscene of Halo 3 before the credits. He is referred to universally by humans simply as the "Master Chief", "Chief" for short and "Sierra-117". Overall he is one of the most recognized characters in gaming history.