Thomas Wagner was from Trost District. A member of the 104th Trainees Squad, he first met Eren Yeager while questioning him about the Colossal Titan. Later, he operated the training gear for the Three Dimensional Maneuver Gear during Eren's second attempt at his aptitude test. At Keith Shadis' orders, Thomas exchanged gear with Eren and it was discovered that Eren's gear was defective. After graduating, Thomas planned to join the Scouting Legion. After the second attack of the Colossal Titan, he was assigned to the middle guard along with Eren Yeager and Armin Arlert. Initially tasked with working under the training corps, they eventually were incorporated into the front guard due to the number of titans. Catching the group unaware, a titan lunged at the rooftop they were standing on. The group scattered but unfortunately, Thomas wasn't fast enough. He was caught and swallowed whole, while his teammate, Eren, looked on in terror.