Thomas “The Train”Petersen

Thomas Petersen is an American professional mixed martial artist competing in the UFC heavyweight division. Known by the nickname “The Train,” he is listed by the UFC as an active fighter who trains at The Striking Institute and uses a boxing-oriented style. Petersen is listed at 6 feet 1 inch with a 74-inch reach.

Before entering the UFC, Petersen developed a wrestling background and became a 2017 NJCAA national champion at Iowa Central. He transitioned into professional MMA and later won a place on the UFC roster through Dana White’s Contender Series. His UFC debut took place on February 3, 2024, against Jamal Pogues.

Petersen has reached several notable career milestones, including winning the LFA heavyweight championship before moving to the UFC. In UFC competition, he earned a decision victory over Mohammed Usman and defeated Don’Tale Mayes by decision. On April 4, 2026, he defeated Guilherme Pat by majority decision. His most recent listed bout was a July 25, 2026, submission loss to Valter Walker by calf slicer.