Robert Downey Jr. was not who Marvel Studios originally had in mind for 2008's Iron Man. Director Jon Favreau and casting director Sarah Halley Flynn knew he was the right choice, but they needed to find a way to pitch it to the studio. Both Favreau and Flynn where convinced that if the studio saw Downey Jr. as Tony Stark, they'd be just as excited as they were about him. So, Flynn came up with the idea of a screen test, which is now a part of the Avengers: Endgame Blu-ray special features.

The screen test was all Marvel Studios needed to see when it came time for choosing Robert Downey Jr. for the first Iron Man movie. "Robert had a whole career of great work behind him," says Jon Favreau. But, he was ready to "breakout" and "do something big," continues Favreau when talking where Downey Jr. was at that point in time. The director was convinced right from the start that Tony Stark had to be played by Downey Jr.

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Jon Favreau's excitement paired with Sarah Halley Flynn's determination to get Robert Downey Jr. a screen test are what caught the studio's attention. As seen in the brief clip of the screen test, Downey Jr. is already Tony Stark before he got the part. He has the swagger and confidence down perfectly in the clip. With that being said, the actor compares the feeling to a main sporting event, admitting it was a rush that made him either feel like he was going to prevail or pass out.

Since the release of Avengers: Endgame, which saw the end of the line for Tony Stark, RDJ has been distancing himself from the MCU and the part that started it all. The actor is not being ungrateful, it's just time to move on as he knows he cannot be Stark and Iron Man forever. Downey Jr. has always done a good job at separating himself from a part, but the MCU took up over a decade of his life, so it's going to be hard for some fans to not see him as the face of the ultra-successful MCU.

Marvel Studios is close to having Avengers: Endgame become the highest grossing movie of all time. It's still unclear if it will be able to dethrone James Cameron's Avatar, but it is slowly catching up. Robert Downey Jr. helped put the MCU on the map with the first Iron Man movie and things could have worked out a lot differently had the studio decided to go with another actor. It was a perfect storm for both parties involved, which has now spawned one of the biggest franchises in entertainment history. While we wait for the Endgame Blu-ray to hit the shelves, you can watch a clip from the Robert Downey Jr. Iron Man screentest below, thanks to the Fandango Twitter account.