20 Times Actors Bet Against Hollywood (And WON)

5. Robert Downey Jr - Iron Man

The Marvel Cinematic Universe is the biggest film franchise there's ever been and, like many others, it started off with the mother of all gambles. They began their series with Iron Man, based on a little-known Marvel superhero and starring Robert Downey Jr, an extremely risky casting on paper. 

While Downey Jr was an Oscar-nominated actor with some acclaimed roles under his belt, he'd had a rough few years due to his drug addiction, and many were reluctant to cast him in case he relapsed again. Furthermore, he wasn't a movie star and casting him as Tony Stark seemed ridiculous... except, once Iron Man came out, it was clear that what had seemed like an idiotic casting choice was actually absolute genius. 

Not only was Downey Jr outstanding, but he was the best fit imaginable. Getting an experienced dramatic actor was vital for conveying Stark's emotional journey throughout the movie and Downey Jr has shown in other projects, such as 2007's Zodiac, that he's a master at playing outwardly charismatic characters with turmoil raging beneath the surface. Downey Jr vividly realized Stark's transformation and gave the movie a huge heart. It is because of him that it works so well, and who knows? The MCU might not even have taken off without him. 

With this part, Downey Jr went from Hollywood pariah to one of the driving forces behind the world's biggest film IP - that is an uplifting journey to rival that of Tony Stark.