Ncuti Gatwa
The Doctor

Millie Gibson
Ruby Sunday

Anita Dobson
Mrs Flood

Varada Sethu
Belinda Chandra / Mundy Flynn

Susan Twist
Susan Triad / Comms Officer Gina Scalzi (uncredited) / Hiker / Tea Lady / Penny ...

Michelle Greenidge
Carla Sunday

Angela Wynter
Cherry Sunday

Jemma Redgrave
Kate Lethbridge-Stewart

Alexander Devrient
Colonel Christofer Ibrahim

Nicholas Briggs
The Vlinx (voice) / Robots (voice) / Omega (voice)

Bonnie Langford
Melanie Bush

Yasmin Finney
Rose Noble

Aidan Cook
The Vlinx

Sienna-Robyn Mavanga-Phipps
Poppy

Ruth Madeley
Shirley Bingham

Jonathan Groff
Rogue / Rogue (archive footage) (uncredited)

Jonah Hauer-King
Conrad Clark

Archie Panjabi
The Rani

Lenny Rush
Morris Gibbons

Aneurin Barnard
Roger ap Gwilliam / Roger ap Gwilliam (archive footage)