James Purefoy

Thomas Marshall

Kate Mara

Lady Isabel

Jason Flemyng

Becket

Paul Giamatti

King John

Brian Cox

Albany

Derek Jacobi

Cornhill

Charles Dance

Stephen Langton, Archbishop of Canterbury

Aneurin Barnard

Guy

Jamie Foreman

Coteral

Mackenzie Crook

Marks

Rhys Parry Jones

Wulfstan

Vladimir Kulich

Tiberius

Annabelle Apsion

Maddy

Steffan Rhodri

Cooper

Bree Condon

Agnes

Guy Siner

Oaks

Kenneth Collard

Sapper Captain

Simon Nader

Hungarian Mercenaries (voice)

Dan Burman

Mercenary Scout (uncredited)