Gene Barry as Dr. Clayton Forrester

Ann Robinson as Sylvia Van Buren

Lewis Martin as Pastor Dr. Matthew Collins

Les Tremayne as Maj. Gen. Mann

Frank Kreig as Fiddler Hawkins (uncredited)

Vernon Rich as Col. Ralph Heffner

Sandro Giglio as Dr. Bilderbeck

Ann Codee as Dr. Duprey (uncredited)

Robert Cornthwaite as Dr. Pryor (as Bob Cornthwaite)

Cedric Hardwicke as Commentary (voice) (as Sir Cedric Hardwicke)

Houseley Stevenson Jr. as Gen. Mann's Aide (as Housely Stevenson Jr.)

William Phipps as Wash Perry (as Bill Phipps)

Jack Kruschen as Salvatore

Paul Birch as Alonzo Hogue (uncredited)

Paul Frees as Second Radio Reporter / Opening Announcer

Henry Brandon as Cop at Crash Site

Peter Adams as Pine Summit Fire Watcher (uncredited)

Eric Alden as Man (uncredited)

Hugh Allen as Brigadier General (uncredited)

Ruth Barnell as Mother (uncredited)

Edgar Barrier as Prof. McPherson (uncredited)

Russ Bender as Dr. Carmichael (uncredited)

Oscar Blank as Man in Church (uncredited)

Hazel Boyne as Screaming Woman (uncredited)

Chet Brandenburg as Man in Church (uncredited)

George Bruggeman as Soldier (uncredited)

Nora Bush as Woman in Church (uncredited)

Tony Butala as Boy in Final Church (uncredited)

Mushy Callahan as Burning Soldier at Pit (uncredited)

Dick Cherney as Looter (uncredited)

Edward Colmans as Spanish Priest (uncredited)

James Conaty as Man at Pacific Institute of Science and Technology (uncredited)

Russ Conway as Rev. Bethany (uncredited)

Martin Coulter as Marine Sergeant (uncredited)

Vittorio Cramer as First Radio Reporter (uncredited)

Pierre Cressoy as Frenchman (uncredited)

Oliver Cross as Scientist (uncredited)

Jane Crowley as Woman in Church (uncredited)

Jim Davies as Marine Commanding Officer (uncredited)

Helen Dickson as Woman in Church (uncredited)

Ralph Dumke as Buck Monahan (uncredited)

Jimmie Dundee as Civil Defense Official (uncredited)

Al Ferguson as Police Chief (uncredited)

Dick Fortune as Marine Captain (uncredited)

Alex Frazer as Dr. James (uncredited)

Frank Freeman Jr. as Bum #2 Listening to Radio (uncredited)

Slim Gaut as Radio Listener (uncredited)

Charles Gemora as Martian (uncredited)

Ned Glass as Well-Dressed Looter (uncredited)

Jack Gordon as Man in Church (uncredited)

Fred Graham as Looter (uncredited)

Joe Gray as Looter (uncredited)

Herman Hack as Worker Listening to Radio (uncredited)

Nancy Hale as Young Wife (uncredited)

Virginia Hall as Girl (uncredited)

Ted Hecht as KGEB Reporter (uncredited)

Douglas Henderson as Staff Sergeant (uncredited)

Gertrude Hoffmann as Elderly News Vendor (uncredited)

Tex Holden as Man in Church (uncredited)

Jimmie Horan as Party Guest (uncredited)

Patricia Iannone as Girl (uncredited)

Jerry James as Reporter (uncredited)

Michael Jeffers as Worker Listening to Radio (uncredited)

Dick Johnstone as Man in Church (uncredited)

Carolyn Jones as Blonde Party Guest (uncredited)

Don Kohler as Colonel (uncredited)

Ivan Lebedeff as Dr. Gratzman (uncredited)

Freeman Lusk as Secretary of Defense (uncredited)

Herbert Lytton as Chief of Staff (uncredited)

Wilbur Mack as Official (uncredited)

George Magrill as Traffic Cop (uncredited)

Mike Mahoney as Townsman (uncredited)

John Mansfield as Man (uncredited)

Joel Marston as Military Policeman in Jeep (uncredited)

Sydney Mason as Fire Chief, Crew #3 (uncredited)

John Maxwell as Doctor (uncredited)

Mathew McCue as Man in Church (uncredited)

David McMahon as Minister, First Church (uncredited)

William Meader as P.E. Official (uncredited)

Lee Miller as Reporter (uncredited)

Ralph Montgomery as Los Angeles Red Cross Official (uncredited)

Alvy Moore as Zippy (uncredited)

Bob Morgan as Injured Civil Defense Worker (uncredited)

Charles Morton as Worker Listening to Radio (uncredited)

George Nardelli as Military Officer (uncredited)

Stanley Orr as Marine Major (uncredited)

George Pal as Bum #1 Listening to Radio (uncredited)

Walter Richards as Reporter (uncredited)

Robert Rockwell as Forest Ranger at Crash Site (uncredited)

Walter Sande as Sheriff Bogany (uncredited)

James Seay as Air Force Bomber Pilot (uncredited)

Allen D. Sewall as Man in Church (uncredited)

Lucile Sewall as Woman in Church (uncredited)

Cora Shannon as Old Woman (uncredited)

David Sharpe as Looter (uncredited)

Teru Shimada as Japanese Diplomat (uncredited)

Reginald Lal Singh as Military Officer (uncredited)

Bobby Somers as Deputy at Crash Site (uncredited)

Bert Stevens as Man in Church (uncredited)

Charles Stewart as Marine Captain (uncredited)

Jack Stoney as Looter (uncredited)

Gus Taillon as Elderly Man (uncredited)

Morton C. Thompson as Reporter (uncredited)

Arthur Tovey as Party Guest (uncredited)

Dale Van Sickel as Looter (uncredited)

Dorothy Vernon as Elderly Woman at Square Dance (uncredited)

Anthony Warde as Military Police Driver (uncredited)

Bob Whitney as Military Officer (uncredited)

Chalky Williams as Worker Listening to Radio (uncredited)

Waldon Williams as Boy (uncredited)

Bud Wolfe as Rescuing Civil Defense Worker (uncredited)

Fred Zendar as Marine Lieutenant (uncredited)