Cullen Gillaspia joined the Aggie Football program in 2014 as a walk on. He was red-shirted that year. In 2015, Cullen saw limited action appearing against Ole Miss, Arizona State, and LSU. He registered his first career tackle against the Tigers to finish the 2015 season.
2016 was a completely different story for the walk-on, redshirt sophomore from Katy, Texas. At the conclusion of fall camp, Cullen Gillaspia was informed that he had been put on official scholarship by the team. On September 2nd, he was named the official “12th Man” for the season ahead. Cullen played all 12 games this season, finishing with 9 total tackles (6 solo, 3 assists) a forced fumble and a fumble recovery.