The cast of Season 9 of “Doctor Who” is just getting bigger and bigger. BBC recently announced that yet another celebrity guest star will join Peter Capaldi in his second series outing as The Doctor on the hit science fiction show. 

According to the Guardian, former “League of Gentlemen” star Reece Shearsmith will join The Doctor and his trusty companion Clara Oswald (Jenna Coleman) in a mysterious guest role during an episode in Season 9. For those unfamiliar with Shearsmith, his connection to the “Doctor Who” canon is tangential at best, but it does exist. He played Patrick Troughton in the BBC docu-drama about the conception and early days of “Doctor Who,” titled: “An Adventure in Space and Time.” The short film was meant to compliment the series’ immensely popular 50th anniversary special. 

According to the BBC, Shearsmith will play a character written by co-producer and “Sherlock” star Mark Gatiss. Speaking to the outlet he said that the episode has been “brewing in the dark recesses” of his mind for a while and he’s very excited to bring in the actor to help tell the story. 

“I am absolutely thrilled to be filming ‘Doctor Who’ as Mark Gatiss has written a fantastic role for me in a very scary episode,” Shearsmith said in a statement. “It has been so exciting to be part of a very singular episode - which, I can say with authority will be unlike any previous episode of ‘Doctor Who.’ It’s a joy to play a part in the show - certainly a badge of honour.”  

While Shearsmith is an exciting addition to the cast of “Doctor Who” Season 9, he’s small potatoes compared to the guest star that everyone has been talking about. It was previously revealed that “Game of Thrones” star Maisie Williams will have a small, but substantial, guest role on the series starting in episode 5. Recently, showrunner Steven Moffat took a moment at the BBC TCA press tour to dispel rumors that Williams will play a role that was previously introduced on the show. Meanwhile, the series plans to bring back Michelle Gomez as Missy in the Season 9 premiere.

How will Missy’s return be explained? What is Shearsmith’s episode about? Who in the world is Maisie Williams playing? Fans will have to tune in when the show returns on Sept. 19 to find out the answers to all these burning questions.