9. James Corden
James Corden has a leg up on some of the other candidates on this list because he's already appeared in a couple of episodes as sort-of-companion Craig. He was nearly turned into a Cyberman in one of them, though, which puts him in good stead to take on the other adversaries that time and space would have on offer. True, he's currently in domestic bliss with his long time crush Sophie and their baby Alfie (whom the Eleventh Doctor insists really wants to be known as 'Stormageddon'), but that doesn't write him off completely. After all, if Clara can balance a full time regular life, working as an English teacher at Coal Hill School and being romantically entangled with Danny Pink, with her TARDIS adventures, why couldn't Craig? Alfie could even accompany then every now and again,
something many fans would like to see. Besides, the Doctor would also get him back to his family in time for tea. Well, he'd at least try to, anyway. What's more, Corden's duties as the new the host of The Late Late Show - recently vacated, coincidentally, by the aforementioned Craig Ferguson - don't entirely rule him out as the new companion, either. He could simply pop in for a couple of episodes as an interim traveller with the Doctor. It would almost be worth it just to see his puzzled reaction to the Twelfth Doctor, who is about as far from Matt Smith as you can get.