A 'Game Of Thrones' actress is coming to 'Doctor Who'

Maisie Williams is a busy young woman.

She's one of Westeros' most fierce and fascinating characters on HBO's "Game Of Thrones," playing Arya Stark, which has its fifth season premiere on April 12th.

And now she's about to enter the TARDIS in BBC's decades-old show, "Doctor Who."

The show's official twitter account announced the casting today with a picture of Williams in front of the famous TARDIS console (that's The Doctor's famous space ship). According to the announcement, Williams will be a guest star in the show.

We're not sure yet how many episodes she'll be in or who's she playing yet. But the show's official website published a feature about her appearance with some quotes from both Williams and "Doctor Who" executive producer Steven Moffat.

Williams said of her casting, "I'm so excited to be working on Doctor Who 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."

Moffat chimed in, "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."

The show has received mixed reviews since actor Peter Capaldi took over the role of The Doctor at the start of last season. It's certainly gone in a much different direction than the show did with the popular Matt Smith playing the doctor for three seasons previous.

Williams will act alongside Jenna Coleman who announced she'll be reprising her role as The Doctor's all-important companion Clara Oswald again for season 9.

This news will almost certainly be a popular one for fans of both "Game Of Thrones," and "Doctor Who."