3. Shona
The recent Last Christmas was one of the best Christmas Specials of the Moffat era, but while it might have been all about the Doctor meeting Santa Claus, many would like to see a rematch between the Doctor and a very different character from the episode. Namely, Shona, the gobby pseudo-scientist unlucky enough to be attacked by a Dream Crab. The scene in which she wakes from the dream world was the longest of all the characters and even hinted at a fuller life for Shona ('Forgive Dave' on her itinerary, for example). This could have simply been something to make this one off character slightly more three-dimensional or it might have been a sneaky hint that there's plenty more of Shona to come in the future. As refreshingly down-to-earth character, and one very different from Clara, many have been calling for her to be the next companion. In fact, here are
10 reasons why she should be. As Moffat has previous for introducing companions-to-be while the current companion is still around (Asylum of the Daleks, anyone?), this could well - nay, should - be the case with her, too. As always, only time will tell.