Dame Harriet Walter makes her Doctor Who debut in the festive special Revolution Of The Daleks.
The stage and screen star, who celebrated her 70th birthday in September, recently appeared in Killing Eve as the nefarious Dasha, a Russian hit man and former Olympic gymnastics champion.
The BBC also confirmed that the special episode will be broadcast on BBC One on New Years 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 of Arachnids In The UK disgusted the Doctor and her companions.
It was previously announced that John Barrowman will be returning for the episode as Captain Jack Harkness.
Aside from a very brief appearance on the episode Fugitive Of The Judoon in January of this year, Captain Jack was last seen on Doctor Who in the 2010 episode The End Of Time.
In Revolution Of The Daleks, Barrowman will reprise the role of the intrepid alien hunter as he helps Yaz, Ryan and Graham fight against the show’s most famous villains.
Meanwhile, Jodie Whittaker’s doctor still can’t help them in their fight, locked up in a maximum-security space prison far from Earth and her Tardis.
Chris Chibnall, executive producer, said, “We stuffed this year’s Doctor Who party special with an explosion of extraordinary acting talent.
“Where else could you get British acting kings, a world famous American movie star, an (inter) national treasure of stage and film and one of Britain’s hottest young actors – only in the guest cast!
‘Put that together with Jodie Whittaker, Bradley Walsh, Mandip Gill and Tosin Cole (and Daleks! Did I mention Daleks!) – and you get a cast that requires extermination. And things will explode. Promise.”