Robert Taylor

as Lt. Col Paul W. Tibbets

Eleanor Parker

as Lucey Tibbets

James Whitmore

as Maj. William M. Uanna

Larry Keating

as Maj. Gen. Vernon C. Brent

Larry Gates

as Capt. William Parsons

Marilyn Erskine

as Marge Bratton

Stephen Dunne

as Maj. Harry Bratton

Robert Burton

as Gen. Samuel E. Roberts

Hayden Rorke

as Dr. Ramsey

Lawrence Dobkin

as Dr. Van Dyke

Jack Raine

as Dr. Fiske

Jonathan Cott

as Capt. Dutch van Kirk

Jeff Richards

as Maj. Thomas Ferebee

John McKee

as Sgt. Wyatt E. Duzenbury

Dick Simmons

as Capt. Robert A. Lewis (Co-Pilot, Enola Gay)

Jim Backus

as Gen. Curtis E. LeMay

Bess Flowers

as Wife at Washington D.C. Airport

Lee MacGregor

as Gen. Robert's Aide

Robert Stevenson

as Military Officer (uncredited)