Sergeant Major Castillo was born and raised in Bayamon, Puerto Rico. He enlisted in the Marine Corps on December 2001 from Spokane Valley, Washington and attended recruit training at Marine Corps Recruit Depot San Diego, California in September 2002. He was assigned to Hotel Company, 2nd Recruit Training Battalion.
After completion of recruit training and Marine combat training in Camp Pendleton California, Private First Class Castillo reported to the Basic Field Wireman's Course at Marine Corps Communications Electronics School, Twentynine Palms, California. Private First Class Castillo was assigned to Charlie Battery 1st Battalion 11th Marines, Camp Pendleton California where he was promoted to Lance Corporal. From September 2003 to March 2004 he deployed with the 13th Marine Expeditionary Unit (SOC) to Al-Faw Iraq during Operation Sweeny in support of Operation Iraqi Freedom.
April 2004 he was promoted to Corporal. From September 2004 to April 2005, Corporal Castillo deployed with Regimental Combat Team 1 Communications Platoon in support of Operation Iraqi Freedom. During his deployment, he was attached to 1st Battalion 503rd Regiment (U.S. Army) as an Enhance Position Location System (EPLRS) operator in support of security operations in Fallujah and Ramadi Iraq. Upon return from deployment he was promoted to Sergeant. In March 2006 Sergeant Castillo reported to Marine Corps Security Forces Battalion in Chesapeake Virginia for Security Forces School. In April 2006 he reported to Marine Corps Security Force Naval Base Kitsap Bangor where he served as a Section Leader and Sergeant of the Guard for Marine Corps Security Force Company Bangor, Fourth Platoon. During his tour, Sergeant Castillo was selected as the Battalion and Regimental Non-Commissioned Officer of the year for calendar year 2008.
In March 2009 Sergeant Castillo reported to H&S Company, 1st Battalion 3d Marines aboard MCB Kaneohe Bay Hawaii. On 2 April 2009 he was meritoriously promoted to the rank of Staff Sergeant and transferred to H.Q. Company 3d Marine Regiment Communications Platoon. He served as Communications Platoon Sergeant and Switching Section Supervisor during Rim of the Pacific (RIMPAC) exercise and winter Mountain Warrior Training in Bridgeport California. In October 2011 Staff Sergeant Castillo transferred to H&S Company 2nd Battalion 3d Marines where he served as a Switching Chief and Communications Platoon Sergeant. From May through November 2012 he deployed to Camp Schwab, Okinawa Japan as part of a Unit Deployment Program. In September 2012, Staff Sergeant Castillo was attached to III Marine Expeditionary Force Special Operations Training Group (III MEF SOTG) in support of 31st Marine Expeditionary Unit Certification Exercise (CERTEX) in Tinian, Peleliu and Guam islands.
In March 2013 Staff Sergeant Castillo reported to Bravo Company, 9th Communications Battalion aboard MCB Camp Pendleton, California where he served as Switching Section SNCOIC. From November 2013 to October 2014 he deployed to Tactical Base Dwyer in Helmand Province, Afghanistan in support of Operation Enduring Freedom 13-2, 14-1 and 14-2, where he served as the Systems Control Watch Officer and Communications Chief for Tactical Base Dwyer. Upon return from deployment he received orders to Recruiting Duty. In May 2015 Staff Sergeant Castillo reported to Recruiting Station Seattle to serve as a Canvassing Recruiter for Permanent Contact Station Spokane Valley, Washington. He was promoted to Gunnery Sergeant in August 2015 and was selected to serve as a Station SNCOIC for Recruiting Sub-Station Hayden, Idaho in March 2016. While on Recruiting duty, his Recruiting Sub-Station earned Recruiting Sub-Station of the year twice at the Recruiting Station level and Recruiting Sub-Station of the year for the 12th Marine Corps District.
In June 2018 he reported to Marine Wing Communications Squadron 38 aboard MCAS Miramar, California where he served as Platoon Commander for Networking and Systems platoons in Bravo Detachment. In March 2019 he was promoted to First Sergeant and assigned to Alpha Detachment where he served as Detachment First Sergeant. In January 2021 First Sergeant Castillo reported to Marine Corps Security Force Battalion Bangor aboard Naval Base Kitsap Bangor in Washington State where he served as Company First Sergeant for Bravo Company and Headquarters and Service Company. In January 2023 First Sergeant Castillo was promoted to Sergeant Major and assigned to Recruiting Station Seattle to serve as the Recruiting Station Sergeant Major.
His personal awards include the Navy and Marine Corps Commendation Medal w/ 2 gold stars, and the Navy and Marine Corps Achievement Medal w/ gold star. Sergeant Major Castillo holds a Bachelor’s degree in General Studies with a concentration in Psychology from Southern New Hampshire University.