I think he had come through on maybeFantastic Four, so everybody sort of knew who he was.

Favreau and Feige sat down for aretrospective lookat the film that started the MCU 15 years ago.

For Favreau, casting Downey inIron Manwas the component that was missing that made the film work.

Robert Downey Jr. played Iron Man in the MCU

Robert Downey Jr. played Iron Man in the MCUJay Maidment / Walt Disney Studios Motion Pictures / Courtesy Everett Collection

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He was the puzzle piece that made it all work, Favreau said.

Favreau continued, Once it was him, thats when my life got a lot easier because he understood.

He understood the voice of the character.

WGA West building in Hollywood

And then one by one, people were just signing on board because now it became something interesting.

I remember on later movies well talk about them on the 15th anniversary of those there were dark days.

And I would say to Robert, We wouldnt be in this mess if it wasnt for you.

Meaning, we wouldnt have a studio if it wasnt for him, Feige added.

Watch the full conversation between Favreau and Feige in the video below.