Sergeant major

In the UNSC Marine Corps, Sergeant Major is the ninth and highest enlisted rank, just above First Sergeant, and equal in grade to Master Gunnery Sergeant, although the two have different reponsibilities. Sergeant Major is both a rank and a military "billet". Marine Corps Sergeants Major serve as the senior enlisted Marine in the Corps' units of battalion, squadron or higher echelon, to assist the unit's commander and to handle matters of discipline and morale among the enlisted Marines.

known Sergeant Major's

 * Sergeant Avery Johnson