Robert Downey Jr. is returning to the Marvel Cinematic Universe, but the move may already be doomed.

The 59-year-old actor was revealed as Doctor Doom, the latest villain in the “Avengers” franchise, at San Diego Comic-Con on Saturday — just five years after his previous Marvel role as Iron Man was spectacularly martyred in “Avengers: Endgame.”

“New mask, same task,” Downey Jr. declared to the Comic-Con audience.

Many Marvel fans had expected the Oscar winner to return to the franchise as Tony Stark or some variant of the Iron Man character, and were reasonably shocked by the bizarre casting choice.

Fans of the Fantastic Four comics have long waited to see Doctor Doom return to the big screen, and many were disappointed by what they saw as a casting gimmick, mocking Marvel’s decision on social media.

“When Dr. Doom reveals his face and looks like Tony Stark,” one fan snarked, using a popular gif of Miley Cyrus taking off her wig in “Hannah Montana.”

Some fans joked the only reasonable excuse to recast Downey Jr. is that MCU President Kevin Feige simply forgot the 59-year-old’s “Oppenheimer” co-star Cillian Murphy’s name. Murphy had long been a fan favorite for the supervillain online, with many claiming the Scottish actor was made for the role.

“Robert Downey Jr. as Dr. Doom could be the laziest movie casting ever.. it feels not right..” a Marvel fan commented on X.

Another fan criticized fellow Marvel moviegoers who believed the casting choice was “so stupid, it’s brilliant,” reiterating that, no, it’s “just dumb.”

Others blasted the comics giant as money-hungry and only interested in playing off fans’ nostalgia for the early revival of the MCU in the late 2000s.

“I don’t even have words but the way the MCU has completely reduced itself to cash-grabs and nostalgia with no sense of creativity has to be studied,” one fan wrote on X.

“If you’re going to pay a bunch of money to get back Robert Downey Jr., I don’t get having him play Dr. Doom. Just have him play Iron Man again. I can even write for you how that’s possible,” another said, referencing a common Marvel trope to miraculously bring back dead character.

The fan added that the decision to bring back the actor and the Russo Brothers — who directed both “Avengers: Infinity War” and “Endgame” — seemed like a “‘break glass in case of emergency’ thing.”

Fans felt that Marvel’s decision to recast Downey Jr. was bizarre

“I get it’s multiversity and blah blah blah, but Iron Man being Doctor Doom means absolutely nothing to the MCU as we know it and does nothing for the character Doctor Doom. It’s just to sell tickets. It’s boring, disrespectful to my fave, and doesn’t make sense. Next,” a different fan added.

While some fans pointed out that Tony Stark is a version of Doctor Doom on the comics’ Earth-11029, Marvel squashed that theory by confirming the character is the original comic-accurate version, named Victor Von Doom.

The MCU has struggled to find new protagonists after the exit of Downey Jr. and Chris Evans, who played Captain America. The franchise has seen a plethora of box office flops since 2019 including “Madame Web,” “The Marvels” and “Shang-Chi and the Legend of the Ten Rings.”

Others made joke predictions of a future X-Men cast that exclusively included former Avengers.

Even Downey Jr’s “Iron Man” co-star Gwyneth Paltrow expressed her confusion on Instagram writing, “I don’t get it, are you a baddie now?”

Feige said the Russo Brothers and Downey Jr’s Doctor Doom will be featured in May 2026’s “Avengers: Doomsday” and May 2027’s “Avengers: Secret Wars.”