SgtMaj Sean J. Grantham

Brigade Senior Enlisted Leader
United States Marine Corps

Sergeant Major Sean J. Grantham attended recruit training at Marine Corps Recruit Depot San Diego in August 2001 and subsequently completed the Tactical Air Defense Controller Course at Marine Corps Air Ground Combat Center Twentynine Palms, California. He reported to Marine Air Control Squadron 1 (MACS-1), MCAS Yuma, Arizona in May 2002, where he was promoted through the rank of Sergeant and deployed three times in support of Operation Iraqi Freedom between 2003 and 2006. In January 2008, Staff Sergeant Grantham reported to Marine Air Command and Control Squadron Experimental (MACCS-X) for aviation command and control equipment test and development as the Air Defense Division Chief.

Sergeant Major Grantham received orders to recruiting duty. From 2011 to 2014, he served at Recruiting Station Orange as a production recruiter and Recruiting Sub-Station SNCOIC, earning promotion to Gunnery Sergeant. Gunnery Sergeant Grantham returned to MACS-1 (EW/C Detachment) at MCAS Miramar and deployed in support of Operation Inherent Resolve, Operation Enduring Freedom, and the Combined Defense of the Arabian Gulf in July 2014. Following deployment, he served as a Detachment Senior Enlisted Advisor and later reported to MACS-4 in Okinawa, Japan in 2016 to serve in the same capacity.

Promoted to First Sergeant in 2017, Sergeant Major Grantham served with 3d Maintenance Battalion, Camp Kinser, Okinawa, and later at Marine Combat Training Battalion, School of Infantry-West. He was promoted to Sergeant Major in June 2022 and assigned to VMGR-152 in Iwakuni Japan, followed by assignment to Marine Aviation Logistics Squadron 12 in January 2024.

In June 2025, Sergeant Major Grantham reported to the United States Naval Academy, where he served as the Marine Detachment Senior Enlisted Leader, worked closely with the Stockdale Center for Ethical Leadership, and served as a military instructor for ethics (NE203). In January 2026, Sergeant Major Grantham was appointed to serve as the United States Naval Academy Brigade Senior Enlisted Leader.

Sergeant Major Grantham’s personal awards include the Meritorious Service Medal with one gold star in lieu of second award, Navy and Marine Corps Commendation Medal with one gold star in lieu of second award, Navy and Marine Corps Achievement Medal with one gold star in lieu of second award, and the Army Achievement Medal.