David Tennant 18 April 1971
If you look at this man's credentials on Wikipedia it makes you wonder how he ever gets any sleep! He does radio, he does television, he does films and he narrates films! One of the few of the Doctor Who's who went on to do more after Doctor Who than he did before. This shows the tenacity of the man, he recently played Richard II with the Royal Shakespeare Company and it would seem that is how he lives his life. As a king set to conquer and conquer and conquer! Right now he's conquering US television with an adaption of Broadchurch which he's already played differently in the United Kingdom. This alone indicates his tenacity!
There is strong indication as he goes through spring and summer that his thoughts are on something solid like a return to the Royal Shakespeare Company, and he seems to be on a roll as he goes through June, July and August. It would seem he is going to be doing something completely different from what we normally find him doing and to be honest there is opportunity for him to click in Hollywood, I don't know if this is on his long-term plan but it may well be and of course he will do very well, although I can't imagine him doing an American accent but that may be my limitation rather than his.
It is very strange that some of the most wonderful actors that we produce are also the most incredibly secretive people you could imagine, it really is not a case of what you see is what you get. What you see with David is what he wants you to see and underneath that he's a completely different person, a lot more humorous than his character would lead you to believe.