Master chief petty officer

Master Chief Petty Officer is the ninth enlisted rank of the UNSC Navy, and is a Non-Commissioned Officer (NCO). It is equal in rank to Master Gunnery Sergeant and Sergeant Major in the UNSC Marine Corps. Master Chief Petty Officer ranks just above Senior Chief Petty Officer.

In informal settings, Master Chief Petty Officers are typically called "Master Chief" or "Chief."