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
Story
William Alland
Director of Photography
Scotty Welbourne
Creature Design
Jack Kevan
Screenplay
Martin Berkeley
Set Decoration
Russell A. Gausman
Editor
Paul Weatherwax
Art Direction
Alexander Golitzen
Julia Heron
Alfred Sweeney
Producer
Herman Stein
Sound Editor
Albert E. Kennedy
Sound
Jack A. Bolger, Jr.
Leslie I. Carey
Ben Hendricks
Costume Designer
Jay A. Morley Jr.
Stunts
Assistant Director
Fred Frank
Music Supervisor
Joseph Gershenson
Musician
Ethmer Roten
Hans J. Salter
Hairstylist
Joan St. Oegger
Ginger Stanley
Milton Rosen
Unit Production Manager
Edward Dodds
Bob Hoy