Who needs dragons when you’ve can time travel?

Fantasy worlds are about to collide when “Game of Thrones” actress Maisie Williams guest stars on “Doctor Who.” BBC America announced Monday that Williams, best known for playing Arya Stark in “GoT,” will appear on the upcoming ninth season of the sci-fi series, which stars Peter Capaldi as the doctor.

“I’m so excited to be working on ‘Doctor Who’ as it’s such a big and important part of British Culture,” Williams said in a press release. “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.”

Little is known about Williams’ role besides the fact that she’ll challenge the doctor and “give him exactly the right sort of hell,” according to lead writer and executive producer Steven Moffat. Season 9 of the show will follow the doctor and Clara Oswald (Jenna Coleman) on two new adventures, “The Girl Who Died,” written by Jamie Mathieson and Moffat, and “The Woman Who Lived,” by Catherine Tregenna.

While “Doctor Who” doesn’t return until the fall, we can expect to see a whole new side of Williams’ Arya on “Game of Thrones” in Season 5. The actress has hinted at a “big ending” for the Stark girl this season, but don’t worry, she’s likely referring to book spoilers and her new makeover.

“Doctor Who” returns in the fall on BBC America.