David Harbour On Working with RDJ For 'Avengers: Doomsday': "Powerhouse"

David Harbour attended the 2026 Emmy Awards and spoke to the press about working with Robert Downey Jr. in Avengers: Dooomsday. The actor, who plays Red Guardian, showered his co-star with praise.

“That guy is a creative powerhouse, so unpredictable… It’s just a joy, he told Variety. “The movies are such a joy to work on, like ‘Thunderbolts*,’ ‘Black Widow.’ So to have us all come together, you have these very surreal moments where I’ve watched these movies for 10 years, and I’ve cheered in the audience when Captain America gets the hammer or whatever, and so to be on set when things like that are happening is just surreal and amazing. I’m a fan and an actor.”

Everything you need to know about Avengers: Doomsday

The villain of the fifth Avengers movie will be Doctor Doom, played by Robert Downey Jr., the actor who portrayed the legendary Iron Man in the MCU's Infinity Saga and now takes on the role of the antagonist. Avengers: Doomsday will be directed by brothers Anthony and Joe Russo (Endgame), with a script by Michael Waldron (Loki) and Stephen McFreely (Endgame).

Marvel has already confirmed the main cast members for the new film, in one of the biggest MCU star reunions ever assembled. Returning from previous Avengers films are: Chris Evans as Steve Rogers, Chris Hemsworth as Thor, Anthony Mackie as Captain America, Sebastian Stan as the Winter Soldier, Paul Rudd as Ant-Man, Winston Duke as M'Baku, and Letitia Wright as Shuri/Black Panther.

Among characters introduced after Avengers: Endgame — in phases 4 and 5 of the MCU — we have Simu Liu as Shang-Chi, Danny Ramirez as Falcon, the entire new Fantastic Four (Pedro Pascal as Mister Fantastic, Vanessa Kirby as Invisible Woman, Joseph Quinn as Human Torch, and Ebon Moss-Bachrach as the Thing), almost the entire cast of Thunderbolts* (Florence Pugh as Yelena, Wyatt Russell as U.S. Agent, David Harbour as Red Guardian, Hanah John-Kamen as Ghost, and Lewis Pullman as Bob, the Sentry), and Tenoch Huerta as Namor.

The film also features the return of the classic X-Men from the old Fox movies, including Patrick Stewart as Professor X, Ian McKellen as Magneto, James Marsden as Cyclops, Alan Cumming as Nightcrawler, Kelsey Grammer as Beast, Rebecca Romijn as Mystique, and, introduced in Deadpool & Wolverine, Channing Tatum as Gambit.

Avengers: Doomsday opens on December 18, 2026.