10. Craig Ferguson
There are many reasons as to why Craig Ferguson would be a perfect fit for Doctor Who. As mentioned in the introduction, he's Scottish, so that shared nationality would be something that he and the Twelfth Doctor would already have in common (although the show might have to start featuring subtitles for the American audiences...). As well as that, though, he's a talented actor and comedian with an impressive history in television and an added bonus is that Doctor Who has featured heavily on the late night talk show he's hosted for many years. That's probably the most important reason he'd make a wonderful addition to the TARDIS. Ferguson is a huge, huge, huge fan of the show and no one has done more than him to introduce new fans to the Doctor's adventures. He has talked extensively on his Late Late Show about the show, interviewed many of its notable figures, including the current Doctor and companion, and has been a huge booster for the series' ratings in the US in general. For him, becoming a series regular would be a dream come true.