9. Paterson Joseph
Continuing on the practical train, Joseph tested well for the role of the Doctor alongside Matt Smith a few years back. Take that knowledge along with author Neil Gaiman stating that they did, in fact, approach a black actor to play the role this time around but he declined, and you've got another potential candidate for the role of his nemesis. Is it likely an actor they potentially approached to play the Doctor himself, which he turned down, would then turn around and play the character's villain? Unlikely. But the interwebs sure does love to speculate. And the show has, aside from Mickey Smith, Martha Jones, and the recently cast Sam Anderson as Danny Pink in series 8, for the most part, lacked color. I think it's high time they broke that trend and started embracing some change. Joseph has had a long career and it's safe to assume that anyone who tests well to play the Doctor might not have such a hard time turning that character on its head in order to play its antithesis. He's even recently said he's a little glad he wasn't cast in the titular role as it would mean the inevitable fame and the inability to walk down a street without being recognized. Now he doesn't have to deal with that and is allowed to live in anonymity. However, even though he may have turned down the role of the hero in order to avoid the fame, playing the role of the Master wouldn't be too thin of a theory since it means a significant part on a significant show without the droves of public recognizing you. Maybe it was all part of his plan?