5. Mark Gatiss
A lot of people think of Mark Gatiss as a showrunner and writer who occasionally puts himself in his own projects. Which is true, to be fair, but it does sort of ignore the fact that he is a legitimately good actor in his own right. Although he definitely has a certain type and verges on the side of camp, most of his work I think most actors would be proud of. He is perfect as Mycroft, Sherlock's bureaucratic older brother, and when you're sharing the screen with Benedict Cumberbatch and Martin Freeman, that's saying something. He manages to walk a very thin line between slightly smarmy and totally unlikeable, and he does it with style. Plus I have to admit, I will always have a soft spot in my heart for his absolutely ridiculous performance in Clone. He plays the homicidal general with a level of panache that I've never seen before. And you know what the best part is? Gatiss is going to reach even more viewers than ever, with his turn as Tycho Nestoris on the upcoming season of Game of Thrones, slated to air in March 2014. If nothing else, he has certainly mastered the art of attaching himself to promising projects.