Jonathan Groff is going from Knock at the Cabin to knockin' on the door of the TARDIS.

The Tony-nominated actor has been announced as the latest addition to the already-stacked cast for the upcoming 60th anniversary of Doctor Who. While Groff's character is currently being kept under wraps, the BBC said “he’s on his way to jump aboard the TARDIS in a mysterious and exciting guest role."

The BBC statement announcing his casting says Groff "hits another high note... in a key role," and after the recent reveal of Jinkx Monsoon's piano-themed costume, could a Doctor Who musical episode be in the works?

“I am so thrilled to jump into the extraordinary mind of Russell T Davies and watch the incredible Ncuti Gatwa soar in this iconic role," the Looking actor said about joining the sci-fi series.

Doctor Who showrunner, Russell T Davies added: “This is an incredible coup, and a great honour, to get such a huge star striding on to our set. So strap on your space boots, this is going to be a blast!” On his Instagram, Davies teased that Groff's appearance will be "coming your way" in 2024.

As Logo previously reported, David Tennant is stepping back inside the TARDIS to reprise his role as the fan-favorite Tenth Doctor, as is his companion Donna Noble, who will once again be played by Catherine Tate.

Tennant and Tate will return for three Doctor Who specials set to begin airing in November 2023 where they will face off against a mysterious new villain played by Neil Patrick Harris.

Sex Education star Ncuti Gatwa, who was previously announced as the next Doctor, is now known officially as the Fifteenth Doctor. Fans got a glimpse of him in a teaser trailer where we see him shout: "Someone tell me what the hell is going on here!" Our thoughts exactly.

It was also announced that Heartstopper actress Yasmin Finney would also be joining Doctor Who "playing the character of Rose" leaving fans to wonder if this would be the same Rose — played by Billie Piper — who was the Doctor's companion when the sci-fi series was revived in 2005.

"You’ll find out in 2023, but it’s an absolute joy to welcome Yasmin to the Doctor Who set," added Davies. "We all fell in love with her in Heartstopper, one of those shows which changes the world - and now Yasmin can change the Whoniverse!”

The 60th anniversary Doctor Who specials will air later this year.