Gregory Peck

Robert Thorn

Lee Remick

Katherine Thorn

David Warner

Keith Jennings

Billie Whitelaw

Mrs. Baylock

Harvey Stephens

Damien Thorn

Patrick Troughton

Father Brennan

Martin Benson

Father Spiletto

Robert Rietti

Monk

Tommy Duggan

Priest

John Stride

Psychiatrist

Holly Palance

Young Nanny

Anthony Nicholls

Dr. Becker

Roy Boyd

Reporter

Sheila Raynor

Mrs. Horton

Robert MacLeod

Horton

Bruce Boa

Thorn's Aide

Don Fellows

Thorn's Second Aide

Miki Iveria

First Nun

Betty McDowall

American Secretary

Nicholas Campbell

Marine

Ronald Leigh-Hunt

Gentleman at Rugby Match (uncredited)

Guglielmo Spoletini

Italian Taxi Driver (uncredited)

Freda Dowie

Nun (uncredited)

Michael Byrne

Monk (uncredited)

Leo McKern

Carl Bugenhagen (uncredited)

Michael Leader

Rugby Match Spectator (uncredited)