David Bradley as William Hartnell

Jessica Raine as Verity Lambert

Sacha Dhawan as Waris Hussein

Brian Cox as Sydney Newman

Lesley Manville as Heather Hartnell

Jeff Rawle as Mervyn Pinfield

Claudia Grant as Carole Ann Ford

Jemma Powell as Jacqueline Hill

Jamie Glover as William Russell

Reece Shearsmith as Patrick Troughton

Nicholas Briggs as Peter Hawkins

Carole Ann Ford as Joyce

Edmund C. Short as Peter Purves

Joseph Railton as Brian Hodgson

Andrew Woodall as Rex Tucker

Ian Hallard as Richard Martin

David Annen as Peter Brachacki

Sam Hoare as Douglas Camfield

Sarah Winter as Delia Derbyshire

Reece Pockney as Alan

Mark Eden as Donald Baverstock

William Russell as Harry

Toby Hadoke as Cyril

Cara Jenkins as Judith Carney

Anna-Lisa Drew as Maureen O'Brien (uncredited)

Sophie Holt as Jackie Lane (uncredited)

Robin Varley as Michael Craze (uncredited)

Ellie Spicer as Anneke Wills (uncredited)

Kit Connor as Charlie (uncredited)

Matt Smith as Self / The Doctor (11) (uncredited)

William Hartnell as The Doctor (1) (archive footage)