I was thinking about the idea of a Doctor Who Prequel of The Doctor's early years on Gallifrey, and one actor immediately popped into mind: Colin Firth. For starters: Firth has been on a roll recently with an Oscar victory for his role in The King's Speech as well as equal acclaim in films such as A Single Man & Tinker Tailor Soldier Spy; he has become a national treasure for British Cinema, much like other actors on this list; and finally his Doctor could very much work as a mysterious incarnation with a cold and cynical look on the universe. I doubt Firth could pull off a more aloof comedic side of The Doctor very well, but when it comes to serious dramatic characters, he can create possibly a very dark incarnation of The Doctor that would leave a mark on the audience, unlike any of The Doctors have ever done.