Lieutenant Colonel Sean F. X. Barrett graduated from Harvard College in 2007 with an A.B. in economics and commissioned as a second lieutenant in the U.S. Marine Corps. After graduating from The Basic School and Signals Intelligence Officers Course, he checked into 2nd Radio Battalion. Sean deployed in support of Operation IRAQI FREEDOM, serving as the intelligence advisor to 1st Brigade, 1st Iraqi Army Division. He also deployed in support of Operation ENDURING FREEDOM as the Charlie Company Executive Officer and the Signals Intelligence Collections Manager for Regional Command Southwest.
In 2011, Sean was selected into the Junior Officer Strategic Intelligence Program. He earned a Master of Science in Strategic Intelligence from National Intelligence University in 2012 and served one-year tours in the Office of Intelligence and Analysis, U.S. Department of Treasury and International Operations Division, Federal Bureau of Investigation. Sean graduated from the MAGTF Intelligence Officers Course in 2014 and subsequently checked into 1st Marine Raider Battalion. He served as the MSOC B S2 and deployed in support of Operation ENDURING FREEDOM-Philippines as the J2/Joint Intelligence Support Element Officer in Charge. He then served as the 1st MRB S2 and deployed in support of Operation INHERENT RESOLVE as part of Special Operations Task Force-North, also assuming multiple responsibilities in operations section.
Sean was selected to attend the Naval Postgraduate School in 2017. He graduated with a Master of Science in Management with distinction and from the U.S. Naval War College JPME I program with highest distinction. Sean then served as the operations officer for the HQMC Directorate of Analytics & Performance Optimization and at Intelligence Division as the program manager for Marine Corps PED and Marine Corps Minotaur, the service representative for Project Maven, and the Van Riper Team Officer in Charge. In July 2021, Sean was awarded a PhD in War Studies from King’s College London, and he also checked into 1st Radio Battalion, where he served as the operations officer and then executive officer. In July 2023, he checked into I Marine Expeditionary Force G2, where he served consecutive assignments as the Operations Officer, Deputy, and acting AC/S. In June 2025, he executed orders to assume command of 3rd Radio Battalion.
Sean competes for the All-Marine running team and has qualified for the Conseil International du Sport Militaire Cross Country Championship multiple times. He placed third in the 2010 Marine Corps Marathon and fourth in 2019 and 2022. He was named the Marine Corps Male Athlete of the Year for 2010 and earned the Major General Michael E. Ennis Award for Literary Excellence in 2013. He has been published in several academic and professional journals. His personal decorations include the Bronze Star with gold star in lieu of second award, the Meritorious Service Medal with gold star in lieu of second award, the Navy Achievement Medal, and the Army Achievement Medal. He is married to Elizabeth Fleming, a practicing attorney. They have a daughter, Alice.