2. Robert Downey Jr.
Having fallen into an existence based entirely around the consumption of excessive drinking and drugs (one that had begun to threaten his career as an actor), Hollywood looked just about ready to toss Robert Downey Jr. out on his ass, until - one day - he decided to get his act together and start afresh. Thank God: over the past decade, Downey Jr. has remerged as one of the most bankable stars in Hollywood, an actor pretty much beloved by all. In both Tony Stark and Sherlock Holmes, Downey Jr. has created rendered two very iconic characters at the helm of two very successful franchises. But both these protagonists - though troubled, flawed geniuses - are about as heroic as they come, which means that Downey Jr. is now best-associated with characters of that type - snarky, detached, ironic boffins. Now that he has those guys in the bag, though, how about a villain? Can you imagine how terrifying it would be to have somebody like Downey Jr. hamming it up as a psychopath? Very, I say. And considering that these characters are the epitome of good guy roles, it'd be interesting to see that transition play out at a point in Downey Jr.'s career where he's so insanely associated with playing heroes.