7. James Nesbitt
The Hobbit star might have spent most of his career playing nice guys - particularly in seminal British romantic comedy-drama Cold Feet - but he has offered one role that offers a tantalising look at what he could bring to Who as The Valeyard. Back in 2007, Nesbitt played the twin leads in Jekyll, another modern take on the Dr Jekyll and Mr Hyde story, which in fairness should have been called Hyde, considering how strongly Nesbitt played the darker side of the character's coin. Dripping with disarming, dark charisma, Nesbitt's Hyde was a remarkably clever creation, ignoring the usually more monstrous elements of the characterisation to create a more subtle grotesque portrait whose hallmarks would transfer perfectly into Who. As with the greatest of the grand school of villainy, Nesbitt oozes on-screen charm - which is probably why he was chosen to play Bofur for Peter Jackson - and that would feed well into the fandom's expectations of what a Doctor Who casting should be based upon (which this Valeyard casting would ostensibly be.) Nesbitt would also fit the profile of actors who have played key villains in the past - especially Simon Pegg (the Editor) and John Simm (the Master) who both came from predominantly comic backgrounds with flashes of dramatic brilliance.