Rex Reason
Dr. Thomas Morgan
Jeff Morrow
Dr. William Barton
Leigh Snowden
Marcia Barton
Gregg Palmer
Jed Grant
Maurice Manson
Dr. Borg
James Rawley
Dr. Johnson
David McMahon
Capt. Stanley
Paul Fierro
Morteno
Lillian Molieri
Mrs. Morteno
Frank Chase
Steward
Larry Hudson
State Trooper
Ricou Browning
The Gill Man (in water)(uncredited)
Don Megowan
The Gill Man (on land)(uncredited)
George Sowards
Ranch Hand (uncredited)
