5. Toby Whithouse
Another veteran of the revived series, Whithouse has penned a total of four episodes, which vary wildly in quality and reception (on the high end of the spectrum is "School Reunion", and far down on the low end is "A Town Called Mercy"). "School Reunion" in particular proves his ability to be a good showrunner for Doctor Who, showing both an understanding of the new series (with how well the characters were portrayed) but also a passion for the classic series (as this was the episode that gave us Sarah Jane Smith and K-9 back). And of course, no one questions his skill at being a showrunner, given the success of his current show "Being Human" and his older series "No Angels".