Tim Holt

Lt. Cmdr. John 'Twill' Twillinger

Audrey Dalton

Gail MacKenzie

Hans Conried

Dr. Jess Rogers

Barbara Darrow

Jody Simms

Max Showalter

Dr. Tad Johns

Harlan Warde

Lt. Robert 'Clem' Clemens

Gordon Jones

Sheriff Josh Peters

Mimi Gibson

Sandy MacKenzie

Marjorie Stapp

Connie Blake

Jody McCrea

Seaman Fred Johnson

Wallace Earl

Sally

Dennis McCarthy

George Blake (lab assistant)

Sarah Selby

Mrs. Simms

Milton Parsons

Lewis Clark Dobbs

Charles Tannen

Seaman Wyatt (Radioman)

Robert Benevides

Seaman Morty Beatty

John Carlyle

Monster Victim

John Close

Deputy Larry

William Forrest

Admiral Greenhouse

Gil Frye

Deputy Scotty