2. Idris
But she IS the TARDIS I hear you shout, shes in every episode! This is correct, of course, but The Doctors Wife saw the first appearance of Idris and I think it is a unique enough event to warrant praise alongside other one-off characters. The story of Neil Gaimans episode, 'The Doctors Wife, made it an instant classic but if Suranne Jones performance had not been so spectacular the character may have been seen as a missed opportunity. Twisting shifts in her mannerisms and her reactions towards Matt Smith's Doctor made the warmth and connection of their relationship instantaneous. Idris allowed the audience to look forward and look back at the same time. Although we will likely never see Idris in human form again, interactions with the TARDIS will never be the same now we know she likes to be called sexy!