The first photos of "Game of Thrones" star Maisie Williams in costume for her guest role on "Doctor Who" have leaked from the set of the British sci-fi series.

The images, captured by photographer Matthew Horwood during filming near Castell Coch in South Wales, suggest the 18-year-old actress is playing a stagecoach-robbing masked bandit in the upcoming episode.

Williams' guest role was announced in March by the BBC. “I’m so excited to be working on ‘Doctor Who’ as it’s such a big and important part of British culture,” she said at the time. “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.”

The actress can currently be seen as Arya Stark in the fifth season of HBO's "Game of Thrones." “Doctor Who” begins its new season this fall.

(via BuzzFeed)