Tim Holt
Lt. Cmdr. John 'Twill' Twillinger
Acting
Audrey Dalton
Gail MacKenzie
Acting
Hans Conried
Dr. Jess Rogers
Acting
Barbara Darrow
Jody Simms
Acting
Max Showalter
Dr. Tad Johns
Acting
Harlan Warde
Lt. Robert 'Clem' Clemens
Acting
Gordon Jones
Sheriff Josh Peters
Acting
Mimi Gibson
Sandy MacKenzie
Acting
Marjorie Stapp
Connie Blake
Acting
Jody McCrea
Seaman Fred Johnson
Acting
Wallace Earl
Sally
Acting
Dennis McCarthy
George Blake (lab assistant)
Acting
Sarah Selby
Mrs. Simms
Acting
Milton Parsons
Lewis Clark Dobbs
Acting
Charles Tannen
Seaman Wyatt (Radioman)
Acting
Robert Benevides
Seaman Morty Beatty
Acting
John Carlyle
Monster Victim
Acting
John Close
Deputy Larry
Acting
William Forrest
Admiral Greenhouse
Acting
Gil Frye
Deputy Scotty
Acting
Joseph Hamilton
Other Lock Watchman
Acting
Charles Herbert
Boy with Morty's Cap
Acting
Byron Kane
Coroner Nate Brown
Acting
Ralph Littlefield
Gatekeeper
Acting
David McMahon
Patterson
Acting
Ralph Moody
Watchman at Lock 57
Acting
William Swan
Seaman Howard Sanders
Acting
Hal Taggart
Davis - Resort Owner
Acting
Mack Williams
Captain Masters
Acting
Dan Gachman
Deputy Brewer
Production
Michael Dugan
Clarke
Acting