Dame Harriet Walter will make her Doctor Who debut in the festive special, Revolution Of The Daleks.
The star of stage and screen, who celebrated her 70th birthday in September, was recently seen in Killing Eve as the nefarious Dasha, a Russian assassin and former Olympic gymnastics champion.
The BBC also confirmed the special episode will air on BBC One on New Year’s Day.
Dame Harriet will guest star alongside Nathan Stewart-Jarrett, who recently appeared in The Trial Of Christine Keeler.
Chris Noth also returns as the disgraced Jack Robertson, whose questionable actions in the 2018 episode Arachnids In The UK left the Doctor and her companions disgusted.
It was previously announced that John Barrowman will return for the episode as Captain Jack Harkness.
Aside from a very brief appearance during the episode Fugitive Of The Judoon in January this year, Captain Jack was last seen on Doctor Who in the 2010 episode The End Of Time.
Revolution Of The Daleks will see Barrowman reprise the role of the fearless alien hunter as he aids Yaz, Ryan and Graham in their battle against the show’s most famous villains.
Meanwhile, Jodie Whittaker’s Doctor remains unable to help them in their fight, trapped inside a high-security space prison far from Earth and her Tardis.
Chris Chibnall, executive producer, said: “We’ve crammed this year’s Doctor Who festive special with an explosion of extraordinary acting talent.
“Where else would you get British acting royalty, a globally renowned US screen star, an (inter)national treasure of stage and screen and one of Britain’s hottest young actors — just in the guest cast!
“Put those together with Jodie Whittaker, Bradley Walsh, Mandip Gill and Tosin Cole (and Daleks! Did I mention Daleks!) — and you get a cast to be exterminated for. And things will explode. Promise.”