President Thaddeus E. "Thunderbolt" Ross is the former Lieutenant General of the United States Army who became the Secretary of State for President Matthew Ellis. During his career, he was put in charge of their military project called the Bio-Tech Force Enhancement Project, with Ross' main aim being to find ways to recreate the Super Soldier Serum. However, the experiment led to an accident which then transformed the scientist Bruce Banner into Hulk. After their long chase, Banner got captured, only for Ross' subordinate officer Emil Blonsky to use all their experiments to transform into the monstrous Abomination. In the face of these odds, Ross was forced to accept Hulk as an ally, allowing him to escape after the fight in New York City, as Ross had been left humiliated by such a disastrous defeat.
Six years after this incident, Ross left the Military and served as the United States Secretary of State. During this time, Ross approved of the Sokovia Accords, which aimed to control the actions of enhanced individuals, primarily the Avengers due to their past actions. As Captain America publicly disowned their accords before going on the run with the Winter Soldier, Ross instructed Iron Man to bring them into custody. Ross arrested many of the Avengers, although Captain America would later break them out following the arrest of Helmut Zemo. Ross led the manhunt for Natasha Romanoff, although later deciding to forgive her after she took down the Red Room and ended General Dreykov's plans for world domination.
Ross' actions with the Accords eventually proved deadly since the divided Avengers failed to stop Thanos from causing the Snap, killing trillions of people, including Ross. After he was resurrected in the Blip, Ross attended Tony Stark's funeral.
