Michelle Gomez will be joining Doctor Who as the Gatekeeper of the Nethersphere.
Gomez said: "Well of course Peter Capaldi is our next Doctor, which makes complete sense. I’m thrilled to join him."
Showrunner Steven Moffat added: "I’ve known Michelle for years, and I’m thrilled to welcome her to Doctor Who.
"She’s everything we need - brilliant, Scottish, and a tiny bit satanic."
"Sitting here, right now, just before the [series eight] finale shooting block, I’ve figured out the cliffhanger to the penultimate episode of the next series," he wrote.
"And it’s a whopper. Ohh, I don’t think you’ll see this coming!"