Dr. Thomas Morgan

Rex Reason

Acting

Dr. William Barton

Jeff Morrow

Acting

Marcia Barton

Leigh Snowden

Acting

Jed Grant

Gregg Palmer

Acting

Dr. Borg

Maurice Manson

Acting

Dr. Johnson

James Rawley

Acting

Capt. Stanley

David McMahon

Acting

Morteno

Paul Fierro

Acting

Mrs. Morteno

Lillian Molieri

Acting

Steward

Frank Chase

Acting

State Trooper

Larry Hudson

Acting

The Gill Man (in water)(uncredited)

Ricou Browning

Acting

The Gill Man (on land)(uncredited)

Don Megowan

Acting

Ranch Hand (uncredited)

George Sowards

Acting