In Halo: Reach, the player character who joins Noble Team has the call sign Noble Six.
Noble Six is a Spartan-III soldier assigned to Noble Team after the previous sixth member is killed. The character is intentionally customizable, so the player can select armor appearance and, in some versions, gender. Within the story, Noble Six is treated as an exceptionally capable but largely unknown operative.
The campaign follows Noble Team during the Covenant invasion of the human colony world Reach in 2552. Because the game is a prequel to Halo: Combat Evolved, its story leads toward the destruction of Reach and the escape of the UNSC Pillar of Autumn. Noble Six is not the same character as Master Chief, who is absent from most of the campaign.