20 Marvel Stars React to Robert Downey Jr.'s Massive Doctor Doom Announcement

Robert Downey Jr.'s return to the MCU as Doctor Doom came as a shock not only to fans everywhere, but to the franchise's own stars as well.

Even after Avengers: Doomsday confirmed over 20 of the movie's major players among its cast, fans and MCU actors alike still can not get over RDJ's original San Diego Comic-Con announcement. 

As the next Avengers flick commences filming, with Doomsday set photos starting to trickle out, here's a look back at some of the biggest MCU stars' reactions to Downey's casting as Doom.

Every Marvel Actor's Reaction to Doom Casting (So Far)

Jeremy Renner (Hawkeye)

Speaking to Us Weekly, Jeremy Renner explained that he "had no idea" that Robert Downey Jr. would be returning to the MCU to play Doctor Doom, and that "this son of a bitch didn’t say anything to me, and we’re good friends:"

"I had no idea ... This son of a bitch didn’t say anything to me, and we’re good friends."

He added that after the announcement, he "started blowing up [Downey’s] phone" via an Avengers group chat, asking if Downey "hiding this from us?" Of course, he is looking forward to what his friend will do in this new role, telling Us Weekly, "That’s exciting news, man. I’m really, really excited about it:"

"I’m like, 'What’s going on? Are you hiding this from us?' I don’t know ... That’s exciting news, man. I’m really, really excited about it."

Mark Ruffalo (Hulk)

Mark Ruffalo shared his reaction to Downey's Doctor Doom announcement on X (formerly Twitter), writing in a quote post the day after the announcement: "Hey Brat, green suits you."

Don Cheadle (War Machine)

Don Cheadle told Collider that when he learned about Downey playing Doctor Doom, he "was like, 'What the f***?'" He said that he "can't even tease anything" regarding the MCU's future, as Marvel is constantly "rewriting" and "reworking."

Benedict Cumberbatch (Doctor Strange)

Benedict Cumberbatch shared a very similar reaction to Cheadle, telling Variety that his first instinct was to text Marvel Studios president Kevin Feige. The Doctor Strange star initially messaged "What the f***?" before clarifying that it was a good "Good what-the-f***. I mean, good what-the-f***."

Elizabeth Olsen (Wanda Maximoff)

In an interview with The Standard, Elizabeth Olsen said she found out after "lots of people were texting" her and she "had to go on the internet to find out:"

"Lots of people were texting me saying, 'I can’t believe this about Downey, did you know?' and I was like, 'I have no idea what you’re taking about' and had to go on the internet to find out."

Kathryn Hahn (Agatha Harkness)

At a live recording of the Happy Sad Confused Podcast in New York City — which The Direct attended — Kathryn Hahn told host Josh Horwitz that "no one tells anybody anything," and that "All of it [referring to Downey's announcement] is a complete, delightful surprise."

Jeff Goldblum (Grandmaster)

In another episode of the Happy Sad Confused Podcast, Jeff Goldblum learned about Downey's return from Horwitz, about a month after it was first announced. He said that he had "vaguely heard ... whispers" about it before the podcast recording, but did not have much to say on Downey himself, focusing isntead on the name Victor Von Doom:

"Excellent news. I think I’d vaguely heard, yes yes I’d heard whispers on my peripheral, yes, channels. Victor Von Doom? I like that name."

Brie Larson (Captain Marvel)

Brie Larson shared with The Playlist in an interview that she had no idea about Downey's return to the MCU as Doctor Doom. In fact, she said that she " was just with Kevin [Feige]" on "like that same day," and that he did say "we're doing a thing at Comic-Con," he did not elaborate:

"I want to be clear. I was just with Kevin [Feige]. It was like that same day ... And he was like, 'Oh yeah, we’re doing a thing at Comic-Con.' He did not say that at all! Not at all!"

David Harbour (Red Guardian), Wyatt Russell (US Agent), and Sebastian Stan (Bucky Barnes)

Three stars of the upcoming Thunderbolts* movie, David Harbour, Wyatt Russell, and Sebastian Stan briefly spoke with Entertainment Tonight at San Diego Comic-Con, just after Downey's announcement.

Harbour started by commenting that "these interviews are just going to be like us going 'Uhhhh," before calling the news a "bombshell that just got dropped."

Russell continued, saying "God is back." Stan did not really speak (he started a sentence but got cut off), though it does not seem that he knew anything the others did not ahead of time.

Florence Pugh (Yelena Belova)

Variety actually showed Florence Pugh the footage of Downey's announcement and saw her real-time reaction during an interview at San Diego Comic-Con right after the announcement happened.

She watched the video with her mouth agape, then said "I didn't see this," and that she "bet[s] it went insane in there."

Julia Louis-Dreyfus (Val) and Lewis Pullman (Sentry)

Rounding out the cast of Thunderbolts*, Julia Louis-Dreyfus and Lewis Pullman spoke with GamesRadar about Downey's news.

Dreyfus kept it simple, saying "That's cool," while Pullman had a bit more to add. He explained that he thinks Downey's return is "a beautiful thing" as the actor "was, in so many ways, the origin of this whole universe:"

"That's amazing. I mean, that's a beautiful thing because he was, in many ways, the origin of this whole universe. That's awesome. Love to hear that."

Joseph Quinn (Johnny Storm)

MCU newcomer Joseph Quinn spoke at MegaCon in Orlando ahead of his debut in The Fantastic Four: First Steps, telling the crowd, via Heroic Hollywood, that he believes that Downey's performance will be "brilliant:"

“I was there. All these masks come out and his mask came off. There were 3,000 people in the audience. The roof blew off. He’s incredible and what he does with this will be equally brilliant.”

Anthony Mackie (Captain America)

Anthony Mackie spoke about Downey's announcement with The Hollywood Reporter, and was immediately ready for a fight with his version of Doctor Doom.

Mackie said that he "better kill him first," and even called "first dibs to knock him off." He then added that he definitely will be fighting Doom, and that he is "not going lightly into this dark night:"

Mackie: "I better kill him first. I get first dibs to knock him off. That’s it."

THR: "Can we see that matchup? Captain America versus Doctor Doom?"

Mackie: "Hell yeah! He’s gonna pull a hamstring or something, I’m gonna take him down. I am not going lightly into this dark night."

Gwyneth Paltrow (Pepper Potts) and Lexi Rabe (Morgan Stark)

Some of Downey's MCU co-stars took to the comments on his Instagram post announcing his return as Doom. For instance, as shared through a screenshot on Film Updates, Gwyneth Paltrow commented, "I don't get it, are you a baddie now?" under Downey's post captioned "New mask, same task."

Lexi Rabe took a similar approach (as reported by ComicBook), but kept it more brief, simply commenting, "Dad?" on the same post.

Frank Grillo (Crossbones) and Zoe Saldana (Gamora)

Frank Grillo and Zoe Saldana were less verbose in their reactions, using emoji symbols instead. Grillo commented with eight fire emoji symbols, the word "amazing," and a starry-eyed emoji, while Saldana commented with seven applause emoji symbols.

BONUS: Julian McMahon (Doctor Doom)

Finally, one of the previous actors to take on the mantle of Doom commented on Robert Downey Jr. assuming the role. Julian McMahon, who played Victor Von Doom in 2005's Fantastic Four, praised the choice at SXSW, via Screenrant:

It's Robert, you know what I mean? What are you going to say? His body of work speaks for itself. He's a super talented guy. I love watching his work

McMahon concluded that Downey's casting as well as cinema's technical advancements over the past couple of years would lead to an "extraordinary" experience:

"If you've got Robert Downey Jr, who's one of the great creatives of the last however many years we've been watching him for, mixed with the elements of how we can make movies these days? I think it's going to be pretty extraordinary."

What About Who Downey Replaced — Kang?

Jonathan Majors is technically no longer in the MCU — in fact, his not being in the MCU is one of the events that led to Downey's announcement at Comic-Con, as Avengers: Doomsday is a replacement for Avengers: The Kang Dynasty.

Speaking with TMZ, Majors shared that he was "heartbroken" about the new direction the MCU is taking with this announcement.

He explained that he "think[s] it's fair" that Downey is seeing "patience and curiosity and love" despite his own troubled past (and said the same of the SnyderVerse's Ezra Miller), but that he "didn't really get that:"

"I think it’s fair that Mr. Downey is being and has been greeted with patience and curiosity and love, and that ... Miller has gotten the same treatment, and that they’re being allowed to work their art. I didn’t really get that, so..."

Later in the interview he said that if he could, we would want to play Kang again, which he has reiterated to the press since. However, this possibility will likely remain in hypotheticals, given how much has happened in the fallout of his firing from the MCU.

Avengers: Doomsday will release in theaters on May 1, 2026.