Gene Barry

Clayton Forrester

Ann Robinson

Sylvia Van Buren

Lewis Martin

Matthew Collins

Les Tremayne

General Mann

Frank Kreig

Fiddler Hawkins (uncredited)

Vernon Rich

Ralph Heffner

Sandro Giglio

Dr. Bilderbeck

Ann Codee

Dr. Duprey (uncredited)

Robert Cornthwaite

Dr. Pryor

Cedric Hardwicke

Commentary (voice)

Houseley Stevenson Jr.

General Mann's Aide

William Phipps

Wash Perry

Jack Kruschen

Salvatore

Paul Birch

Alonzo Hogue (uncredited)

Paul Frees

Second Radio Reporter / Opening Announcer

Henry Brandon

Cop at Crash Site

Peter Adams

Pine Summit Fire Watcher (uncredited)

Eric Alden

Man (uncredited)

Hugh Allen

Brigadier General (uncredited)

Ruth Barnell

Mother (uncredited)

Edgar Barrier

Prof. McPherson (uncredited)

Russ Bender

Dr. Carmichael (uncredited)

Oscar Blank

Man in Church (uncredited)

Hazel Boyne

Screaming Woman (uncredited)

Chet Brandenburg

Man in Church (uncredited)

George Bruggeman

Soldier (uncredited)

Nora Bush

Woman in Church (uncredited)

Tony Butala

Boy in Final Church (uncredited)

Mushy Callahan

Burning Soldier at Pit (uncredited)

Dick Cherney

Looter (uncredited)

Edward Colmans

Spanish Priest (uncredited)

James Conaty

Man at Pacific Institute of Science and Technology (uncredited)

Russ Conway

Rev. Bethany (uncredited)

Martin Coulter

Marine Sergeant (uncredited)

Vittorio Cramer

First Radio Reporter (uncredited)

Pierre Cressoy

Frenchman (uncredited)

Oliver Cross

Scientist (uncredited)

Jane Crowley

Woman in Church (uncredited)

Jim Davies

Marine Commanding Officer (uncredited)

Helen Dickson

Woman in Church (uncredited)