Jesse Eisenberg
Simon James / James Simon
Mia Wasikowska
Hannah
Wallace Shawn
Mr. Papadopoulos
Yasmin Paige
Melanie
Noah Taylor
Harris
James Fox
The Colonel
Cathy Moriarty
Kiki
Phyllis Somerville
Simon's Mother
Gabrielle Downey
Strange Woman
Jon Korkes
Detective
Craig Roberts
Young Detective
Kobna Holdbrook-Smith
Guard / Doctor
Susan Blommaert
Liz
Bruce Byron
Skinhead
J. Mascis
Janitor
Tony Rohr
Rudolph
Karima Riachy
Secretary
Tim Key
Care Worker
Andrew Gruen
Man on Train
Kim Noble
Box Man / Guard 1
Morrison Thomas
Coughing Man
Sally Hawkins
Receptionist at Ball
Lloyd Woolf
Investigator
Lydia Fox
Well-Dressed Woman at Ball / Test Invigilator
Stuart Silver
Waiter / 'The Replicator' - Guard 2
Chris Morris
Workers' Services Executive
Chris O'Dowd
Nurse
Donal Cox
Priest
Kierston Wareing
James' Funeral Date
Paddy Considine
'The Replicator' - Jack
Dirk Van Der Gert
'The Replicator' - Head Judge
Liam Bewley
'The Replicator' - Wise Judge
Gemma Chan
'The Replicator' - Glamourous Judge
Nathalie Cox
'The Replicator' - Jack's Wife
Daniel Chapple
Executive Worker (uncredited)
Martin Crossingham
Paramedic (uncredited)
Danny
Singer (uncredited)
Catherine Delaloye
Air Hostess (uncredited)
Lukas DiSparrow
Resident (uncredited)
Joanna Finata
Bar Girl (uncredited)
Jeanie Gold
Waitress (uncredited)
Steve Saunders
Moaning Man on Trolley (uncredited)
Rade Šerbedžija
Frightening Old Man (uncredited)
Natalia Warner
The Girl (uncredited)