On screen
Cast
30 credited performers
John Agar
Prof. Clete Ferguson
Lori Nelson
Helen Dobson
John Bromfield
Joe Hayes
Nestor Paiva
Captain Lucas
Artwork unavailable
Grandon Rhodes
Jackson Foster
Dave Willock
Lou Gibson
Robert B. Williams
George Johnson
Charles Cane
Police Captain
Loretta Agar
Woman on Boat (uncredited)
Bill Baldwin
Patrol Boat Dispatcher (voice / uncredited)
Artwork unavailable
Jere Beery
Photographer (uncredited)
Ricou Browning
The Gill Man (in water) / Lab Technician (uncredited)
Diane DeLaire
Miss Abbott (uncredited)
Artwork unavailable
Mike Doyle
Cop (uncredited)
Clint Eastwood
Jennings (uncredited)
Jack Gargan
Skipper (uncredited)
Artwork unavailable
Charles Gibb
Cop (uncredited)
Brett Halsey
Pete (uncredited)
Don C. Harvey
Mac - Spotlight Party Leader (uncredited)
Artwork unavailable
Tom Hennesy
The Gill Man (on land) / Marineland Diver (uncredited)
Artwork unavailable
Don House
Diver (uncredited)
Robert F. Hoy
Charlie (uncredited)
Artwork unavailable
Ned Le Fevre
Newscaster (uncredited)
Artwork unavailable
Sydney Mason
Police Announcer (uncredited)
Artwork unavailable
Robert Nelson
Dr. McCuller (uncredited)
Artwork unavailable
Patricia Powers
Girl in Convertible
Artwork unavailable
Bert Stevens
Search Party Member (uncredited)
Artwork unavailable
Charles Victor
Policeman (uncredited)
Artwork unavailable
Robert Wehling
Joe (uncredited)
Artwork unavailable
James R. Wolfe
Man at Tank (uncredited)