8. The Master
Of course, The Master will return one day; it is just unknown when. The 50th Anniversary Special, perhaps? Maybe. But when he does return, it is indeed a bold story direction, because the show is at risk of reusing old plots like, Oh its the Master, whats he wanna do? Oh, world domination, you say? Didnt expect that. Okay, yes, maybe thats not so bad; The Master is a fan favourite, nearly appearing in every one of the Third Doctor's earth-bound adventures. I would love to see him come back; I do think John Simm is a brilliant Master, but a regeneration with the Moffat era would be welcomed. Simms' Master was indeed a joker, so a more serious, cunning, evil Master would be a great contrast.