Master chief petty officer

Master Chief Petty Officer is an E-9 rank of the UNSC Navy, and is a non-commissioned officer. It is equal in rank to Master Gunnery Sergeant in the UNSC Marine Corps, Sergeant Major in the UNSC Army, and Chief Master Sergeant in the UNSC Air Force. Master Chief Petty Officer ranks just above Senior Chief Petty Officer and just below Command Master Chief Petty Officer. Note that John-117 was awarded Master Chief Petty Officer of the Navy at the end of Halo 3.