Thunderbolts* star breaks silence on his return in 'Avengers: Doomsday'

David Harbour, who made his Marvel debut in 2021’s Black Widow, has finally opened about his return in the Avengers: Doomsday.

The 50-year-old actor is known to play Alexei Shostakov aka Red Guardian in the MCU movie. He last played the titular role in 2025 Thunderbolts* film, led by Florence Pugh.

While updating fans about his appearance in the upcoming MCU movie, Harbour revealed that he was “not convinced” when he started working on the project.

In conversation with Screen Rant at Rose City Comic Con, the Stranger Things actor stated, “I was not even convinced when we started, and this movie’s gonna be really good.”

During the conversation, the Golden Globe Nominee praised the efforts and talent of the Russo brother, directors of the new Avengers movie.

According to David, they “have a special sauce. I don’t even really understand, but they just know how to do these things.”

He further referenced their past Marvel work including Civil War and Infinity War, saying, “there’s something about the layers in which they put the comedy and the drama and the surprises and the scale and the epicness and all that stuff. It’s incredible.”

Harbour also unveiled that he has never been on a set like the Avengers: Doomsday in his life. “It’s just enormous.”

Led by Robert Downey Jr, the forthcoming action sci-fi is slated to release on December 18, 2026.