A native of Macas, Ecuador, Sergeant Major Gavilanes immigrated to the United States and graduated from Danbury High School in Connecticut in 1998. He enlisted in the Marine Corps on January 29, 1999, and completed recruit training at Marine Corps Recruit Depot Parris Island, South Carolina, in May. Following Marine Combat Training at Camp Geiger, North Carolina, he graduated from the Cannon Crewman Course at Fort Sill, Oklahoma, in July 1999.
From 1999-2003, Sergeant Major Gavilanes served as an artilleryman with Kilo Battery, 3d Battalion, 10th Marines. From 2003-2006, he served as a drill instructor, academics instructor, and testing non-commissioned officer in charge aboard Marine Corps Recruit Depot Parris Island. From 2006-2009, he served as a section chief, platoon sergeant, and battery gunnery sergeant with Kilo Battery, 3d Battalion, 10th Marines. From 2009-2012, he served as the psychological operations senior non-commissioned officer in charge at the Marine Corps Information Operations Center aboard Quantico, Virginia. Froom 2012-15, Sergeant Major Gavilanes served as a platoon sergeant, battery gunnery sergeant, and company first sergeant with 1st Battalion, 10th Marines. From 2015-2017, he served as the assistant Marine officer instructor for the Navy Reserve Officer Training Corps at Yale University, participating in Officer Candidates School’s summer augmentation program as an instructor. From 2017-2018, he served as a company first sergeant with 1st Battalion, 8th Marines. From 2020-2022, he served as a company first sergeant with 2nd Transportation Support Battalion. In February 2022, Sergeant Major Gavilanes was promoted to his current rank and reported Recruiting Station Springfield, Massachusetts, for duty as the recruiting station sergeant major. In March 2025, he reported to 25th Marine Regiment at Fort Devens, Massachusetts, where he currently serves as the regimental inspector-instructor command senior enlisted leader.
His contingency and combat experience includes Operations SWIFT FREEDOM, ENDURING FREEDOM (two deployments), and IRAQI FREEDOM. His additional deployments include sea duty in the Mediterranean with the 26th Marine Expeditionary Unit; Special Purpose Marine Air-Ground Task Force Crisis Response Africa; Okinawa, Japan, with the Unit Deployment Program; and EXERCISE UNITAS.
Sergeant Major Gavilanes' personal decorations include the Meritorious Service Medal, Joint Commendation Medal, Navy and Marine Corps Commendation Medal (with three gold stars), Navy and Marine Corps Achievement Medal (with gold star), and the Combat Action Ribbon.