Comedian John Bishop is to join Jodie Whittaker for the 13th series of Doctor Who, the BBC has revealed.
The 54-year-old, who recently tested positive for coronavirus, said boarding the Tardis was a "dream come true".
He will play a character called Dan, who "becomes embroiled in the Doctor's adventures" and faces "evil alien races beyond his wildest nightmares".
Bishop fills the gap left by Bradley Walsh and Tosin Cole, who bowed out in a special New Year's Day episode.
He began filming his role last November, but the BBC kept the signing under wraps until the broadcast of Revolution Of The Daleks on Friday night.
'Worst illness I've ever had'
Bishop, who grew up on a Merseyside council estate, had a brief career as a professional footballer before turning his hand to comedy.
He has previously acted in the Channel 4 drama Skins and the Ken Loach film Route Irish.
Earlier this week, the comedian revealed that he and his wife had tested positive for Coronavirus over Christmas, saying he had been "flattened" by "the worst illness I have ever had".
Writing on Instagram, he described his symptoms as including "incredible headaches, muscle and joint point, no appetite, nausea, dizziness [and] chronic fatigue like I didn't know existed".
He updated fans on New Year's Eve, saying he and his wife were "getting a little stronger" every day, and promising he would return to work in January.
It is not thought his illness will disrupt production on Doctor Who. The show is on a scheduled break for Christmas and not due to resume filming until later this month.
The 13th series of the rebooted sci-fi stalwart will see Whittaker return as the extra terrestrial Time Lord, alongside Mandip Gill, who returns as Yaz.
In a statement, Bishop said: "If I could tell my younger self that one day I would be asked to step on board the Tardis, I would never have believed it.
"It's an absolute dream come true to be joining Doctor Who and I couldn't wish for better company than Jodie and Mandip."
Programme boss Chris Chibnall added: "It's time for the next chapter of Doctor Who, and it starts with a man called Dan. Oh, we've had to keep this one secret for a long, long time.
"Our conversations started with John even before the pandemic hit.
"The character of Dan was built for him, and it's a joy to have him aboard the Tardis."
Doctor Who will return to BBC One later this year.