Keir Dullea
as Dr. David Bowman

Gary Lockwood
as Dr. Frank Poole

William Sylvester
as Dr. Heywood Floyd

Douglas Rain
as HAL 9000 (voice)

Daniel Richter
as Moonwatcher

Leonard Rossiter
as Dr. Andrei Smyslov

Margaret Tyzack
as Elena

Robert Beatty
as Dr. Ralph Halvorsen

Sean Sullivan
as Dr. Roy Michaels

Frank W. Miller
as Mission Controller (voice)

Bill Weston
as Astronaut

Ed Bishop
as Aries-1B Lunar Shuttle Captain

Glenn Beck
as Astronaut

Alan Gifford
as Poole's Father

Ann Gillis
as Poole's Mother

Edwina Carroll
as Aries-1B Stewardess

Penny Brahms
as Stewardess

Heather Downham
as Stewardess

Mike Lovell
as Astronaut

John Ashley
as Ape

Jimmy Bell
as Ape

David Charkham
as Ape

Keith Denny
as Ape

Jonathan Daw
as Ape

Péter Delmár
as Ape

Terry Duggan
as Ape Attacked by Leopard

David Fleetwood
as Ape

Danny Grover
as Ape

Brian Hawley
as Ape

David Hines
as Ape

Anthony Jackson
as Ape

John Jordan
as Ape

Scott MacKee
as Ape

Laurence Marchant
as Ape

Darryl Paes
as Ape

Joe Refalo
as Ape

Andy Wallace
as Ape

Bob Wilyman
as Ape

Richard Woods
as Ape Killed by Moon-Watcher

Maggie London
as Hostess in Elevator (uncredited)

Chela Matthison
as Receptionist (uncredited)

Judy Keirn
as Voice Print Identification Girl (uncredited)

Vivian Kubrick
as Floyd's Daughter (uncredited)

Kenneth Kendall
as BBC-12 Announcer (uncredited)

Kevin Scott
as Miller (uncredited)

Martin Amor
as Interviewer (uncredited)

S. Newton Anderson
as Young Man (uncredited)

Sheraton Blount
as (uncredited)

Ann Bormann
as (uncredited)

Julie Croft
as (uncredited)

Penny Francis
as (uncredited)

Marcella Markham
as (uncredited)

Irena Marr
as Russian Scientist (uncredited)

Krystyna Marr
as Russian Scientist (uncredited)

Kim Neil
as (uncredited)

Jane Pearl
as (uncredited)

Penny Pearl
as (uncredited)

Burnell Tucker
as TMA-1 Site Photographer (uncredited)

John Swindells
as TMA-1 Site Technician #1 (uncredited)

John Clifford
as TMA-1 Site Technician #2 (uncredited)

Stanley Kubrick
as (voice) (uncredited)

Harry Fielder
as Moonwalker (uncredited)