Filming on Doctor Who season nine (season nine of the show's modern run, that is) is ongoing, with Steven Moffat back again as the head writer/show-runner. Peter Capaldi and Jenna Coleman are reprising their season eight roles as, respectively, the latest regeneration of the Time Lord known as The Doctor and his current human companion, Clara Oswald (who was introduced back during Matt Smith's run on the series).
Today, we have confirmation of a guest star for season nine: Maisie Williams, best known for playing young Arya Stark on HBO's ultra-popular fantasy series Game of Thrones. Filming is currently underway on the episodes "The Girl Who Died" and "The Woman Who Lived" - scripted by, respectively, Moffat and season eight writer Jamie Mathieson ("Mummy on the Orient Express" and "Flatline") and Catherine Tregenna: a Torchwood alum, as well as the first female Doctor Who writer under Moffat's watch as showrunner.
Williams, it seems, might well appear in both of the aforementioned episodes, given the timing of her announcement - which, combined with the related titles of the two "period adventures" (as they're identified in the BBC press release), indicates they will be covering a two-part narrative together. Moffat, in keeping with his traditional approach, played things close to the chest with his official statement about Williams joining the Doctor Who cast for season nine (see below):
“We’re thrilled to have Maisie Williams joining us on Doctor Who. It’s not possible to say too much about who or what she’s playing, but she is going to challenge the Doctor in very unexpected ways. This time he might just be out of his depth, and we know Maisie is going to give him exactly the right sort of hell.”
Not surprisingly, Williams also kept her statement about the news simple - saying she's excited to be working on a show that's "such a big and important part of British Culture," and noting that the episodes in question are shooting relatively close to her hometown: Bristol, England. You can check out an official screenshot of Williams on Doctor Who's current TARDIS set, below.
The over-arcing storyline for Doctor Who season nine remains something of a mystery, seeing as neither the final two season eight episodes nor the subsequent Christmas Special concluded by setting The Doctor and Clara off adventuring in a clear direction. That being said, season nine is confirmed to open with a pair of episodes that bring back Michelle Gomez as "Missy" - who, as we now know, is the latest regeneration of The Doctor's archenemy The Master. Thereafter, it should be clearer what lies ahead for the renegade Time Lord.
Doctor Who season eight was considered by many to be an improvement over season seven (Smith's final term playing The Doctor), but the finale "Death in Heaven" was quite polarizing - once again, prompting many fans to respond by arguing that it's time for Moffat to step down as show-runner (a position that he's held for four seasons now). We'll have to wait and see if their tune changes (or intensifies) over the course of season nine, but at least there will be some fun guest-starring appearances (such as Williams') to anticipate too.
Doctor Who season 9 will begin airing on BBC One in Autumn 2015.