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