This might cause the biggest nerdsplosion since they announced Mark Hamill was going to be guesting on The Flash; the BBC has announced this morning that Maisie Williams, who of course plays the endlessly badass Arya Stark on the equally amazing Game of Thrones, will be a guest star on the upcoming series of Doctor Who. Yep! Two great shows, one great actress.

Of her stint on the perennial sci-fi series, Williams said: “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.” So, she’s a big fan of convenience, that Maisie Williams, but when you spend most of your work life in Northern Ireland and Croatia, it’s probably nice to just be down the street from home.

Lead writer and executive producer Steven Moffat was his usually promotionally happy and cryptic self regarding Williams’ joining the program. “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.” Whatever in the world any of that means.

Doctor Who is in the middle of filming its ninth series, the second with Peter Capaldi as the Doctor and second-and-a-halfth with Jenna Coleman as Clara Oswald. Currently, the episodes being filmed are two period adventures – “The Girl Who Died” written by Jamie Mathieson and Steven Moffat, and “The Woman Who Lived” by Catherine Tregenna, both directed by Ed Bazalgette. I’m intrigued by all of these complimentary titles happening this year; you may remember that the two-part premiere have the titles “The Magician’s Apprentice” and “The Witch’s Familiar,” but both of those are written by Moffat.

As you no doubt know, Game of Thrones will be returning to HBO on Sunday, April 12th, where you can see Ms. Williams on a boat, mothereffers, don’t you ever forget.

How stoked are you for this casting? What’re some of your favorite geek-cast-crossovers? Let us know below!