'Walking Dead' Star Steven Yeun Cast as Major Marvel Superhero

Actor Steven Yeun will be playing Sentry in Marvel's upcoming movie Thunderbolts, but fans aren't supposed to know that just yet. Thunderbolts was announced in June of 2022, and while Yeun was announced as part of the cast, his role was kept under wraps. Last week, however, writer Robert Kirkman mistakenly revealed the role during a livestream on YouTube.

Kirkman is the writer behind the Walking Dead comic books that helped put Yeun on the map, and the creator of Prime Video's Invincible where Yeun now plays Mark Grayson. It's safe to say the two are close, which is presumably how Kirkman had this information that he didn't realize was a secret. On Thursday, he was featured on a livestream with comic book artist David Finch where they were discussing Marvel comics. Kirkman dropped some details without realizing fans wouldn't have them.

"My good friend Steven Yeun is playing The Sentry in a movie," Kirkman said. "He called me, he went in for a costume fitting. I don't think this is a spoiler, or anything that will get anybody in trouble. I don't know, maybe, we'll see. I don't care, I don't work for Marvel. What are they going to do to me?"

The Thunderbolts are a team of superheroes – or antiheroes – that first appeared in Marvel Comics in 1997. In that story, the Avengers were all presumed dead after a previous adventure and the Thunderbolts arose to help fill the gap. However, readers learned from the start that they were villains in disguise, though they eventually took on a more ambiguous alignment.

Sentry is not actually a member of The Thunderbolts in the comics, but one of the other heroes they sometimes come into conflict with. First appearing in 2000, Sentry is a man named Bob Reynolds with the "power of one million exploding suns" thanks to a mysterious "special serum." At some point in the past, Sentry used his enormous power to wipe all memory of himself from the people of earth to protect them from a great threat.

It's not clear if the film adaptation will cover Sentry's origin story and his amnesia, or his most consequential run-ins with the Thunderbolts later on. Thunderbolts will be written by Lee Sung Jin and Eric Pearson and directed by Jake Schreier. Other stars include Sebastion Stan as Bucky Barnes, Hannah John-Kamen as Ghost, Olga Kurylenko as Taskmaster, Florence Pugh as the new Black Widow and David Harbour as Red Guardian.

It's also hard to say when fans will get to see Thunderbolts for themselves. It was originally planned as the second-to-last film in the MCU's "Phase Five," but was later reorganized into "Phase Six." It's current tentative release date is July 25, 2025. There are at least three movies to go before then, plus streaming and TV tie-ins. The Marvels is showing in theaters now.