The playable super-soldier protagonist in Halo: Combat Evolved is Master Chief.
His full designation is Master Chief Petty Officer John-117, commonly shortened to Master Chief or simply the Chief. He is a SPARTAN-II supersoldier created through the United Nations Space Command’s enhancement and training program. In the original game, players follow him as he battles the Covenant and investigates the mysterious Halo installation.
Master Chief is not the same character as the Arbiter, a major Covenant figure introduced as a playable character in Halo 2. He is also distinct from Marcus Fenix, who leads the Gears of War series. The character’s anonymous presentation in the first game helped make him an iconic Xbox protagonist, while later Halo stories revealed more about his childhood, training and relationship with the artificial intelligence Cortana.
Halo: Combat Evolved launched with the original Xbox in 2001 and established Master Chief as one of Microsoft’s best-known game characters.