Robert Downey Jr.

‘Iron Man’ star Robert Downey Jr.'s substance abuse led to him serving a year in California Substance Abuse Treatment Facility and State Prison in the early 00s.

He was also fired from his role on TV show 'Ally McBeal'.

Even once he was sober, the actor's career didn’t pick up again until director Mel Gibson personally underwrote Downey’s liability insurance so that he could star in 2003’s 'The Singing Detective'.

Since then, the Marvel star has turned his life and career around and was even awarded an Oscar for blockbuster 'Oppenheimer'.