John Walker was originally the Thunderbolts villain, but "it didn't work the same"

Thunderbolts* originally had a very different antagonist. Wyatt Russell's John Walker, AKA US Agent, initially had the role Sentry took on in the final version of the movie, according to screenwriter Eric Pearson.

"There are a couple of versions where part of Valentina’s manipulation of them, for John Walker, she convinced him that his Super Soldier Serum was deteriorating and he needed updates," he told ComicBook, referring to Julia Louis-Dreyfus' scheming Contessa.

"He needed to have monthly shots. What she was actually doing was implanting a 'Hulk Bomb,' or I think she even called them 'A Bomb,' which is a very obscure character from the comics. But if she needed to create an event, she could set him off, so he would rage out into this big monster. It was fine, but it didn’t work the same."

Walker made his MCU debut in 2021's Disney Plus series The Falcon and the Winter Soldier. He's the government-appointed replacement for Captain America, but has to leave the post in disgrace after publicly killing a civilian.

“It was fun to make Walker detestable and then make him the person they had to save and have that be his big breakthrough of, 'Oh my god. What an asshole I’ve been,'" Pearson continued, but said he soon realized that "wasn't working" and revisited the comics before deciding to add Sentry into the story instead.

"I was like, 'What if it’s less vague than that and it’s more self-esteem and heroic ambition versus depression and self-loathing and isolation and loneliness?' That’s all our characters’ journeys lumped into one villain, one person, who can be their antagonist. It gave everything we wanted."

Of course, in the final cut, Lewis Pullman's Bob, AKA Sentry, takes center stage, and his alter-ego the Void replaces a Hulked-out US Agent. In the film's final act, the Thunderbolts (or the New Avengers, should we say?) – including Walker – have to team up to save themselves and get the real Bob back after the Void threatens New York City with his dark powers.

Thunderbolts* is out now. For more on the movie, check out our Thunderbolts* review, or get up to speed with our guide to the Thunderbolts* post-credits scenes.