Gregory Peck

as David Stillwell

Diane Baker

as Shela

Walter Matthau

as Ted Caselle

Robert H. Harris

as Dr. Broden

Kevin McCarthy

as Sylvester Josephson

Leif Erickson

as The Major

Walter Abel

as Charles Stewart Calvin

George Kennedy

as Willard

Jack Weston

as Lester

Anne Seymour

as Frances Calvin

House Jameson

as Bo

Hari Rhodes

as Lt. Franken

Syl Lamont

as Benny

Eileen Baral

as Irene

Neil Fitzgerald

as Joe Turtle

Franklin Cover

as Group Leader

Don Anderson

Bill Baldwin

Al Beaudine

Roxane Berard

Robert Brubaker

Toni Covington

John Crowther

Robert Dahdah

Ann Doran

as Tenant in Apartment 3R (uncredited)

Jerry Dunphy

Douglas Evans

Harry Fleer

Rian Garrick

Gerald Gordon

Damian O'Flynn

as Bar Patron (uncredited)

John Pedrini

Barbara Perry

as Office worker (uncredited)

Murray Pollack

as Detective (uncredited)

Bill Quinn

as Eddie - Bartender (uncredited)

Allan Ray

Walter Reed

as Reporter (uncredited)

Victor Romito

George Simmons

Ann Staunton

Bert Stevens

Robert Swan

as Police Sergeant (uncredited)

Aline Towne

as Dr. Broden's Receptionist (uncredited)

Howard Wendell

Myron Healey

as Bar Patron Discussing Watermelon (voice) (uncredited)