Prof. Clete Ferguson
John Agar
Helen Dobson
Lori Nelson
Photographer (uncredited)
Jere Beery
The Gill Man (in water) / Lab Technician (uncredited)
Ricou Browning
Miss Abbott (uncredited)
Diane DeLaire
Cop (uncredited)
Mike Doyle
Jennings (uncredited)
Clint Eastwood
Skipper (uncredited)
Jack Gargan
Charles Gibb
Pete (uncredited)
Brett Halsey
Mac - Spotlight Party Leader (uncredited)
Don C. Harvey
The Gill Man (on land) / Marineland Diver (uncredited)
Tom Hennesy
Joe Hayes
John Bromfield
Diver (uncredited)
Don House
Charlie (uncredited)
Robert F. Hoy
Newscaster (uncredited)
Ned Le Fevre
Police Announcer (uncredited)
Sydney Mason
Dr. McCuller (uncredited)
Robert Nelson
Girl in Convertible
Patricia Powers
Search Party Member (uncredited)
Bert Stevens
Policeman (uncredited)
Charles Victor
Joe (uncredited)
Robert Wehling
Man at Tank (uncredited)
James R. Wolfe
Captain Lucas
Nestor Paiva
Jackson Foster
Grandon Rhodes
Lou Gibson
Dave Willock
George Johnson
Robert B. Williams
Police Captain
Charles Cane
Woman on Boat (uncredited)
Loretta Agar
Patrol Boat Dispatcher (voice / uncredited)
Bill Baldwin
Music
Henry Mancini
Frank Skinner
Makeup Artist
Bud Westmore
Original Music Composer
William Lava
Director
Jack Arnold
Screenplay
Martin Berkeley
Story
William Alland
Director of Photography
Scotty Welbourne
Creature Design
Jack Kevan
Producer
Herman Stein
Editor
Paul Weatherwax
Art Direction
Alexander Golitzen
Alfred Sweeney
Set Decoration
Russell A. Gausman
Julia Heron
Sound
Jack A. Bolger, Jr.
Leslie I. Carey
Sound Editor
Ben Hendricks
Albert E. Kennedy
Costume Designer
Jay A. Morley Jr.
Hairstylist
Joan St. Oegger
Unit Production Manager
Edward Dodds
Assistant Director
Fred Frank
Stunts
Bob Hoy
Ginger Stanley
Music Supervisor
Joseph Gershenson
Milton Rosen
Musician
Ethmer Roten
Hans J. Salter