A non-commissioned officer, usually abbreviated as NCO and occasionally called "noncom," is an enlisted member of the UNSC Defense Forces who has been given leadership authority by commissioned officers.

UNSC Navy NCO Ranks (From lowest to highest pay grades):

• Petty Officer Third Class
• Petty Officer Second Class
• Petty Officer First Class
• Chief Petty Officer
• Senior Chief Petty Officer
• Master Chief Petty Officer
• Command Master Chief Petty Officer
• Master Chief Petty Officer of the Navy

UNSC Marine Corps NCO Ranks (From lowest to highest pay grades):

• Corporal
• Sergeant
• Staff Sergeant
• Gunnery Sergeant
• Master Sergeant/First Sergeant
• Master Gunnery Sergeant/Sergeant Major
• Sergeant Major of the Marine Corps

UNSC Army NCO Ranks (From lowest to highest pay grades):

• Corporal
• Sergeant
• Staff Sergeant
• Sergeant First Class
• Master Sergeant/First Sergeant
• Sergeant Major
• Command Sergeant Major
• Sergeant Major of the Army