Marvel Stars Share Shocked, Confused Reactions to Robert Downey Jr. MCU Return

As the Marvel Cinematic Universe celebrated achieving that new milestone for any franchise, thanks to the massive opening weekend underway for 'Deadpool & Wolverine,' Mackie was either genuinely shocked by the news, or playing it off.

With the way Marvel holds its secrecy sacrosanct, either is possible.

As an interviewer for The Hollywood Reporter told Mackie that RDJ was coming back to the MCU, he turned his head off-camera momentarily as if shocked, but then quickly replied with, "I better kill him first."

The new face of Captain America was referring to the fact that Downey is not returning as Iron Man (aka Tony Stark), but rather one Victor Von Doom. That's right, as part of a larger announcement about Dr. Doom making his MCU presence in a huge way, RDJ was revealed to be under the mask.

"I get first dibs to knock him off," Mackie continued of his one-time superhero ally (at least as far as the actor inside the suit is concerned).

When asked if fans could actually see that match-up, Mackie said, '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."

Downey's Iron Man costar Gwyneth Paltrow -- who always seems a bit confused about where she fits in the MCU -- shared her own reaction on the actor's Instagram post, commenting, "I don’t get it, are you a baddie now?"

Mark Ruffalo, aka Hulk, added, "Hey Brat, green suits you" -- while Hawkeye himself, Jeremy Renner, commented, "Bringing the DOOM 🔥!!!"

Other celebs in awe included Serena Williams -- who wrote, "I love any version of Tony/Robert/doom!" -- Hannah Waddingham, who added, "Now that is f--king cool! 👏" and Seth Green, who commented, "I am entertained."

Florence Pugh also reacted in real time backstage in San Diego:

Downey's reveal was the highlight of the night, based on the rapturous roar that erupted in Hall H when Downey revealed his face. It's not clear if he is meant to look like Tony Stark as part of some in-story continuity, or perhaps he'll just never take the mask off, as Doom (almost) never does in the source material.

RDJ's appearance was the culmination of a reveal that included the return of the Russo Brothers (Joe and Anthony) to the franchise, as well, to helm the next two Avengers films.

Already announced, the films now have directors, a villain, and names: Avengers: Doomsday and Avengers: Secret Wars. The first will introduce RDJ's Doctor Doom to the MCU proper, while the second ... well, that's for the future to tell.

Doctor Doom being the main villain appears to be a major shift for the MCU, which had been setting up Jonathan Majors' Kang as a major Avengers-level player. In fact, it was thought Avengers 5 would be The Kang Dynasty.

But the actor's off-screen legal troubles put a quick kibosh on those plans as Marvel Studios quickly severed ties with him, with The Kang Dynasty reverting to 5 until ... well, until RDJ's big reveal on Saturday night. "New mask, same task," Downey said after unmasking.

Doctor Doom, of course, is one of Marvel's most famous villains, and he's also famously tied to the First Family of Marvel Comics, the Fantastic Four. He and Reed Richards (Mr. Fantastic) were college roommates in the original comics and he has extensive connections to the family, both villainous and even friendly (and familial), on occasion.

Doom isn't the only classic Fantastic Four villain joining the MCU, either, as that epic drone show that kicked off Comic-Con confirmed the appearance of old school Galactus as the major cosmic-level villain the FF will have to deal with in their MCU debut. Footage revealed in Hall H also featured Galactus in all his helmeted glory looming over the Earth.

As for Doom, it was appropriate that his introduction into the MCU comes on the heels of theirs. In fact, it was confirmed that after starring in their own 1960s-set film, fully titled The Fantastic Four: First Steps,, the Fab Four will also be featuring in both of the upcoming Avengers films, as well. No word on how that would work, considering the nearly 60 year gap between the two eras, but it's a brave new era in the MCU, after all.

Dare well call it a Brave New World? That's the subtitle of Mackie's big-screen debut as the new lead for the Captain America franchise, after all. In that same interview, he talked about how the title refers to this new era.

"It shows a new generation of Marvel, a new foundation that we're starting on," he said of his film's title. "Sam Wilson is entering into a brave new forecast of the world that Marvel is becoming, that our situation, our universe is becoming."

"I think it's a great title for everything that's happening with the characters in the movie," he added. Also revealed was the identity of Giancarlo Esposito's villain for Mackie's Brave New World, with the Breaking Bad alum taking on the role of Sidewinder, the leader of the cult-like Serpent Society.

Captain America: Brave New World is part of the closing chapters of Phase 5 of the MCU. That film comes out February 14, 2025, followed by the final film of the era in Thunderbolts*. Yes, that asterisk is intentional and no it wasn't explained at Comic-Con.

The original Thunderbolts comic series featured one of the biggest secrets and twists in the history of comic books, which left fans on the edges of their seats awaiting the next chapter. Will the film simply mirror that twist, or do they have one of their own? Both films are expected to set the stage for Phase 6, or as Mackie put it, "the world that Marvel is becoming."

Phase 6 kicks off with The Fantastic Four: First Steps on July 25, 2025, much as Marvel Comics kicked off with The Fantastic Four all those decades ago. The new era also includes the upcoming Blade movie on November 7, 2025 (unless its delayed), and Avengers: Doomsday on May 1, 2026 and Avengers: Secret Wars on May 7, 2027.