9. Maisie Williams
The revived series has a pretty mixed record when it comes to young actors playing children. For every Remi Gooding (Rupert Pink) or Ellis George (Courtney Woods) whos really impressed audiences, theres been another along to drive them up the wall. Just ask any Whovian for their opinion of the kids in Nightmare in Silver and... well, you're probably best avoiding that topic of conversation altogether, actually, unless you enjoy listening to rants. Maisie Williams could change that. Shes been hugely impressive in Game of Thrones playing Arya Stark, a character several years her junior. She can do forceful, stubborn, naïve - all qualities that could help create a really interesting, well-developed guest character. The acclaim shes been gathering from Thrones could be another great reason for her coming over to Doctor Who, as she might bring a number of viewers with her, too. The fact that she can play a lot younger that herself also helps. It would add some interesting dynamics for a show that is, after all, meant to be for family viewing. Whoever she ends up playing, her interactions with Capaldi and Coleman could be really interesting and, perhaps more importantly, accessible for all.