Dennis G. Keller Jr (DJ) was raised in Gainesville, Florida. He attended Florida International University and graduated with a Liberal Arts degree.
He joined the Marine Corps in June 2008 and attended Officer Candidate School as part of the Platoon Leaders Class in Quantico, Va. After completing OCS, Major Keller reported to The Basic School in March 2010 as part of Charlie Company. After completion of TBS, Major Keller reported to Infantry Officers Course in September 2010 as part of Kilo Company.
In January 2011, Major Keller received orders to 2d Battalion, 9th Marines, Camp Lejeune, NC. He was assigned to Company F and served as a Platoon Commander until February 2012.
Major Keller then received orders to 1st Battalion, 9th Marines in March 2012 to serve as a Company Advisor for an Advisor Training Team. Major Keller then deployed from August 2012 to March 2013 in support of Operation Enduring Freedom.
Major Keller then received orders to Headquarters Company, 8th Marine Regiment in April 2013. He served as the Company Executive Officer until April 2014. Major Keller then served as the Company Commander from April 2014 to March 2015.
In March 2015, Major Keller received orders to Fleet Antiterrorism Security Team (FAST) Company C in Norfolk, Virginia. He served as a Platoon Commander and Company Executive Officer. As Platoon Commander, Major Keller deployed from February to September 2016 in support of FASTCENT operations. Following his return from deployment, Major Keller served as Company Executive Officer for FAST Company C from October 2016 to February 2018.
In March 2018, Major Keller received orders to 3d Battalion, 2d Marines, Camp Lejeune, North Carolina. He served as the Headquarters and Service Company Commander until May 2019. During his tenure, he conducted a deployment to Okinawa, Japan in support of Unit Deployment Program 18.2.
In June 2019, Major Keller received orders to Force Headquarters Group, Marine Forces Reserve where he served as the Global Force Management Officer in Charge (OIC) until May 2022. During his tenure, he oversaw the execution of over 75 deployments in support of all Geographic Combatant Commands.
In June 2022, Major Keller received orders to Canberra, Australia as part of the Personnel Exchange Program where he served as an Operations Research and Analysis Planner directly working with the Australian Defense Force until May 2025. During his time in Australia, Major Keller conducted countless experiments and wargames with coalition partners, the United States Army, and the Marine Corps Warfighting Lab.
In May 2025, Major Keller received order to Echo Company, 2d Battalion, 25th Marines where he is currently serving as the Inspector - Instructor.
Major Keller’s personal awards include Meritorious Service Medal (gold star in lieu of second award) and the Navy Marine Corps Commendation Medal (gold star in lieu of third award).