Lt. Cmdr. John 'Twill' Twillinger

Tim Holt

Acting

Gail MacKenzie

Audrey Dalton

Acting

Dr. Jess Rogers

Hans Conried

Acting

Jody Simms

Barbara Darrow

Acting

Dr. Tad Johns

Max Showalter

Acting

Lt. Robert 'Clem' Clemens

Harlan Warde

Acting

Sheriff Josh Peters

Gordon Jones

Acting

Sandy MacKenzie

Mimi Gibson

Acting

Connie Blake

Marjorie Stapp

Acting

Seaman Fred Johnson

Jody McCrea

Acting

Sally

Wallace Earl

Acting

George Blake (lab assistant)

Dennis McCarthy

Acting

Mrs. Simms

Sarah Selby

Acting

Lewis Clark Dobbs

Milton Parsons

Acting

Seaman Wyatt (Radioman)

Charles Tannen

Acting

Seaman Morty Beatty

Robert Benevides

Acting

Monster Victim

John Carlyle

Acting

Deputy Larry

John Close

Acting

Admiral Greenhouse

William Forrest

Acting

Deputy Scotty

Gil Frye

Acting

Other Lock Watchman

Joseph Hamilton

Acting

Boy with Morty's Cap

Charles Herbert

Acting

Coroner Nate Brown

Byron Kane

Acting

Gatekeeper

Ralph Littlefield

Acting

Patterson

David McMahon

Acting

Watchman at Lock 57

Ralph Moody

Acting

Seaman Howard Sanders

William Swan

Acting

Davis - Resort Owner

Hal Taggart

Acting

Captain Masters

Mack Williams

Acting

Deputy Brewer

Dan Gachman

Production

Clarke

Michael Dugan

Acting