Mel Gibson as James Murray

Sean Penn as Dr. William Chester Minor

Natalie Dormer as Eliza Merrett

Eddie Marsan as Muncie

Jennifer Ehle as Ada Murray

Jeremy Irvine as Charles Hall

David O'Hara as Church

Anthony Andrews as Benjamin Jowett

Ioan Gruffudd as Henry Bradley

Stephen Dillane as Dr. Richard Brayne

Steve Coogan as Frederick James Furnivall

Laurence Fox as Philip Lyttelton Gell

Lars Brygmann as Max Mueller

Brendan Patricks as Winston Churchill

Adam Fergus as Alfred Minor

Brian Fortune as Head Board Member

Aidan McArdle as Defence Attorney Clarke

David Crowley as Parfit

Kieran O'Reilly as Minor's Father

Bryan Murray as Henry Liddell

Oengus MacNamara as Bailiff #1

Christopher Maleki as Joseph

Sean Duggan as Tom Coleman

Bryan Quinn as Sir Richard

Steve Gunn as Lambeth Man

Malcolm Freeman as Colonel

Joe McKinney as Attendant No.1

Olivia McKevitt as Clare Merrett

Shane Noone as George Merrett

Robert McCormack as Harold Murray

Ronan O'Connor as Gate Guard

John Morton as Scriptorium Assistant

Abigail Coburn as Elsie Murray

Paul Gough as Guard

Lucas Browne as Eastman Minor