Jon Favreau says Robert Downey Jr. was in talks to play a different Marvel character before Iron Man

Robert Downey Jr. has been synonymous with Tony Stark ever since he debuted as the billionaire playboy and philanthropist in 2008's Iron Man. But in the grand tradition of Marvel's multiversal madness, Downey was in talks to play an entirely different Marvel character before being cast as Iron Man.

In a new retrospective celebrating the 15th anniversary of the film that kickstarted the Marvel Cinematic Universe, Jon Favreau — who both directed and starred in Iron Man as Happy Hogan — revealed that Downey was initially interested in playing the antagonist of 2005's Fantastic Four.

"I remember you had all met with [Downey] already for like Doctor Doom or something on another project," Favreau said during a conversation with Marvel's top boss Kevin Feige. "I think he had come through on maybe Fantastic Four, so everybody sort of knew who he was."

It was Nip/Tuck's Julian McMahon who ultimately played Victor Von Doom, while Downey went on to don his iconic suit of armor in nine films throughout the MCU. That's not to say Downey couldn't have appeared in Fantastic Four and returned in a different Marvel role down the line — after all, future Captain America Chris Evans appeared in the film as the Human Torch. However, Favreau and Feige both agree that not having Downey as Tony Stark would have rewritten the MCU as we know it.

"He was the puzzle piece that made it all work," Favreau explained. "I remember sitting down with the guy, and I was like, 'He's got that spark in him in his eye and he's ready.' That's when we were in your office, and we were pointing to his headshot, saying, 'We got to try to figure this out.'"

When they brought Downey in for a screen test, Favreau knew immediately that they'd found their Iron Man.

"Once it was him, that's when my life got a lot easier," Favreau said. "Because he understood. He understood the voice of the character. And then one by one, people were just signing on board because now it became something interesting."

Feige, who also recalled Downey's casting as a crucial moment for the movie that launched the MCU, told Favreau, "That tone that you and Robert discovered on that movie, I would say became the template in a way for much of what the MCU became."

He added: "I remember on later movies – we'll talk about them on the 15th anniversary of those – there were dark days. And I would say to Robert, 'We wouldn't be in this mess if it wasn't for you.' Meaning, we wouldn't have a studio if it wasn't for him."

You can watch the full Iron Man retrospective below.

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