Richard Basehart

Adm. Harriman Nelson

David Hedison

Captain Crane

Terry Becker

Chief Sharkey

Richard Bull

Doctor

Del Monroe

Kowalski

Robert Dowdell

Lt. Comdr. Chip Morton

Paul Trinka

Patterson (uncredited)

Marco López

Crewman (uncredited)

Linda Cristal

Acteur

Nick Adams

Acteur

Charles McGraw

Acteur

Leslie Nielsen

Acteur

Victor Buono

Tabor Ulrich

John Cassavetes

Acteur

Yvonne Craig

Acteur

Adam Williams

Chief

Al Ruscio

Acteur

Les Tremayne

Acteur

Danica D'Hondt

Lola Hale

Diane Webber

Mermaid

Douglas Bank

Witt

Judy Lang

Angie

Barbara Bouchet

Tippy Penfield

Regis Toomey

George Penfield

Cyril Delevanti

Noah Grafton

Charles Dierkop

Left-Handed Man

Michael Barrier

Cabrillo

Ted de Corsia

Foreign General

Herbert Lytton

First Admiral

Brooke Bundy

Gundi

Michael Ansara

Capt. Tomas Ruiz

Nicholas Colasanto

Reporter (uncredited)

Lloyd Bochner

Martin Davis

Edgar Bergen

Kenner

Arch Whiting

Sparks (uncredited)

Walter Brooke

Dan Case

Eric Feldary

Deiner

Dayton Lummis

Reinhardt

Roger C. Carmel

Admiral Halder

John Gallaudet

Admiral Johnson

Alfred Shelly

Murphy

David Sheiner

Chandler

Mark Slade

Malone

Frank Ferguson

Air Force General

Damian O'Flynn

Dr. Thompson

Don Knight

Sven Larsen

Henry Kulky

Curley Jones

Arthur Franz

Archer

Alvy Moore

Hoff

Harold J. Stone

Admiral Jiggs Starke

John Banner

Russian Chairman

Edward Platt

Morgan

Nancy Kovack

Monique

Susan Flannery

Stenographer (uncredited)

Patrick Wayne

Fraser

Nick Dimitri

Alien #2 (uncredited)

Carroll O'Connor

Old John

Peter Adams

Johnson

Richard Carlson

Mattson

Anna-Lisa

Sigrid

Steven Geray

Dalgren

Frank Richards

Hassler

James Doohan

Presidential Assistant

Stan Jones

Anderson

Torben Meyer

Proprietor

Greger Vigen

The Boy

Erik Holland

Gartern

Kort Falkenberg

The Father

Gordon Gilbert

O'Brien

Everett Sloane

Gronski

Paul Carr

Clark

Ford Rainey

U.S. President

Robert Carson

S.A.C. General

James Darren

Omir

Seymour Cassel

Jensen

Paul Fix

Sam Burke

Hurd Hatfield

Leopold Zeraff

John Alderson

Round-Face

Peter Brocco

Xanthos

Peter Mamakos

Nicolas

Audrey Dalton

Lydia Parrish

Berry Kroeger

Chairman

Buck Kartalian

Crew Member (uncredited)

Charles Aidman

Dr. Hollis

Chuck Courtney

Crew Member (uncredited)

David Lewis

Dr. Kranz

Eddie Albert

Dr. Fred Wilson

Françoise Ruggieri

Brenda

George Takei

Cheng

Henry Jones

Dr. Sprague

Jacques Aubuchon

Abdul Azziz

John Hoyt

General Beeker

Joseph Ruskin

Inspector Falazir

Joseph Walsh

Atlas

Kevin Hagen

Komal

Malachi Throne

General Gamal

Malcolm Atterbury

Commander Jamison

Michael Constantine

Dr. Brand

Peter Mark Richman

Gantt

Robert F. Simon

President

Ron Stein

Crew Member (uncredited)

Ted Jordan

Astronaut #2 (uncredited)

Troy Melton

Alien (uncredited)

Tyler McVey

Gen. Blake (uncredited)

Vincent Price

Professor Multiple

Viveca Lindfors

Laura

Walter Reed

Scientist (uncredited)

Wayne Heffley

Seaview Doctor (uncredited)

Werner Klemperer

Dr. Gamma (uncredited)