Staff sergeant

Staff Sergeant is the sixth enlisted rank of the UNSC Marine Corps and seventh enlisted rank in the UNSC Army, and is a non-commissioned officer. It is equal to the rank of Petty Officer First Class in the UNSC Navy. The rank is symbolized by four gold chevrons.

They typically command teams of 9 - 11 Marines or Soldiers, although they may be selected to become "Platoon Sergeants", which aid Second Lieutenants. Strangely, Avery Johnson and Nolan Byrne were platoon leaders on Harvest, and were told to train marines for the militia.