Fan Casting U.S. Agent in Marvel Studios' Avengers: Doomsday

John Walker, ex-Army Ranger, became Captain America but clashed with Sam Wilson and Bucky Barnes while chasing Flag Smashers. After taking the Super Soldier Serum and losing his partner Lemar Hoskins, Walker killed a foreign national, losing his title and rank. Recruited by Valentina Allegra de Fontaine as U.S. Agent, he later learned of her betrayal when she sent him and others to kill each other. Forming the Thunderbolts with Yelena Belova, Ghost, and Red Guardian, they saved Manhattan from Bob Reynolds’ Void. De Fontaine redubbed them New Avengers after saving Bob. Fourteen months later, they saw the Fantastic Four’s spaceship enter Earth’s orbit.