Valentina Cortese as Maria Brentano / Brent / Lena Collins

Serge Reggiani as Louis Balan

Audrey Hepburn as Nora Brentano

Megs Jenkins as Penny

Irene Worth as Miss Jackson

Reginald Tate as Inspector Eliot

Charles Goldner as Anselmo

Angela Fouldes as Nora Brentano as a child

Simone Silva as Undetermined (Minor Role - Paris Sequence) (uncredited)

Norman Williams as Sergeant Newcome

Michael Shepley as Manager of the British Pavilion

Athene Seyler as Mrs. Reginald Kellick

Sydney Tafler as Syd Burnett

Geoffrey Hibbert as Steenie

John Ruddock as Daly

Michael Allan as Rodd

John Field as Fedor Luki

Hugo Schuster as General Galbern

Lionel Harris as Frack

Rollo Gamble as Bentley

John Penrose as Bill

John Chandos as John

Michael Ripper as Charlie

Louis Mansi as Member of Paris Committee

John Gabriel as Member of Paris Committee

Olga Landiak as Member of Paris Committee

Frederick Schiller as Galbern's Bodyguard

Phaedros Antonio as Galbern's Bodyguard

Gaston Richer as Queval

Derek Elphinstone as Plain Clothes Man

Edward Evans as Plain Clothes Man

Jack McNaughton as Postman

Ingeborg von Kusserow as Shoe Shop Girl

Bob Monkhouse as Hairdresser

Helen Ford as Scarf Woman

Ann Lancaster as Manicurist

Grace Draper as Floozie

Bertram Shuttleworth as Little Man

Pamela Harrington as Waitress

John Allen as The Valet

Bay White as Nursing Sister

Joe Linnane as Irish Police Inspector

Sam Kydd as Irish Police Sergeant