Benedict Cumberbatch as Stephen Hawking

Peter Firth as Sir Fred Hoyle

Tom Ward as Roger Penrose

Lisa Dillon as Jane Wilde

John Sessions as Dennis Sciama

Phoebe Nicholls as Isobel Hawking

Michael Brandon as Arno Penzias

Tom Hodgkins as Robert Wilson

Alice Eve as Martha Guthrie

Adam Godley as Frank Hawking

Matthew Marsh as Dr. John Holloway

Anastasia Hille as Nurse Susan McClean

Christian Rubeck as Reporter

Bertie Carvel as George Ellis

Carolina Giammetta as Lidia Sciama

Sebastian Armesto as Robert Silkin

Rohan Siva as Jayant Narlikar

Deirdre Costello as Barmaid

Linda Spurrier as Train Passenger

Anthony Howell as Hamlet

Che Cartwright as Guildenstern

Leon Ockenden as Rosencrantz

James Warrior as Cab Driver

David McKail as Frink

Rory Copus as Edgar

Philip McGinley as Chris

Charlie Beall as Hugh

Mark Wells as Cyclist