Sir Lenny Henry and Stephen Fry are set for "major roles" in the first episode of the new series of Doctor Who.
They will appear alongside Jodie Whittaker as she returns as the Thirteenth Doctor, but it is not yet known if they will be friend or foe to the Time Lord and her friends.
It will be a debut stint for the pair in the sci-fi drama.
Doctor Who showrunner Chris Chibnall said that the series will return "with a bang - with two great British icons in major roles".
He added: "One of the great joys of Doctor Who is getting to work with actors from your wish list. Stephen and Lenny are two of my absolute favourite actors - and to be able to bring them into Doctor Who, in our one of our biggest ever stories to kick off the new series, is an absolute thrill."
Sir Lenny said it was "absolutely brilliant to be welcomed into the fantastical world of Doctor Who."
He added: "The nearest I have been to the Tardis was when I played the Caribbean Doctor in the Lenny Henry Show, so as a life-long (hiding behind the sofa type) Doctor Who fan this is a very special moment for me."
Fry said: "Short of being picked for a British space exploration programme and I readily concede that I'm past the age where I'd be considered (if I was ever the right age for such a posting) - then being in an episode of Doctor Who will certainly do as a very sweet second-place excitement."
Whittaker will return alongside co-stars Tosin Cole, Mandip Gill and Bradley Walsh in the new series, which will air next year.
