Hollywood's Biggest Bad Boys
Robert Downey Jr.
The former drug and alcohol addict spent several years checking in and out of rehab in the '90s. Now sober, the Iron Man 2 star told Playboy in November 2010 that it feels like a "lifetime" since he succumbed to his addictions. "Looking back, I think, 'Oh my God, I could have been done,'" he said.