Thaddeus E. "Thunderbolt" Ross is the former Lieutenant General of the United States Army who had served as Secretary of State, originally nominated by Matthew Ellis. During his career, he was put in charge of the Bio-Tech Force Enhancement Project, with Ross' goal being to recreate the Super Soldier Serum. However, the experiment led to an accident which then transformed the scientist Bruce Banner into the Hulk. After their long chase, Banner got re-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, while Ross had been left humiliated.
Ross would leave the military and instead served as the United States Secretary of State. During this time, Ross had approved of the Sokovia Accords, which aimed to control the actions of enhanced individuals, primarily the Avengers. When Captain America publicly disowned the accords, before going on the run, along 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 would also lead a manhunt for Natasha Romanoff, although later deciding to forgive her after she took down the Red Room, and had ended General Dreykov's plans.
Ross' actions resulted in the divided Avengers failing 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.
