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)

Rade Šerbedžija

Frightening Old Man (uncredited)