Game of Thrones star to guest in Doctor Who's ninth season

Game of Thrones' Masie Williams will guest star in an upcoming episode of Doctor Who, according to a BBC press release. Williams plays the youngest Stark daughter Arya Stark, who's spent most of her time in the series masquerading as a boy and plotting nearly impossible revenge on those who have wronged her, though the newest season of the show some of that may be changing.

"I'm so excited to be working on Doctor Who," said the 17-year-old Williams on her first day of filming, "as it's such a big and important part of British culture. I can't wait to meet the cast and crew and start filming, especially as we'll be shooting not too far from my home town."

Notoriously tight-lipped show runner Steven Moffat had only a few hints to drop about the nature of her character on Doctor Who:

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.

In January, Doctor Who began filming a ninth season that promises Peter Capaldi and Jenna Coleman traveling through all of time and space as the Doctor and his companion Clara Oswald, as well as Michelle Gomez as Missy, the latest incarnation of Doctor's timelord nemesis, the Master. When it premieres in the fall, it'll also be the first season of Doctor Who to feature a female writer on any of its episodes in seven years, with ‘The Woman Who Lived' being written by Catherine Tregenna.

The BBC's press release also confirmed the casting of Rufus Hound, Tom Stourton, Ariyon Bakare, Simon Lipkin, Ian Conningham, Murray McArthur, Barnaby Kay, John Voce and Struan Rodger as guest stars in the new season.

Find out more about Maisie and the new series of #DoctorWho at http://t.co/he9Anc81qb pic.twitter.com/OVD9dNnsU3

— Doctor Who Official (@bbcdoctorwho) March 30, 2015