Sal Mineo
Cadet Col. Sylvester Dusik
Charlton Heston
Maj. Bernard R. 'Barney' Benson
Joey D. Vieira
Cadet Cpl. Scawalski (as Donald Keeler)
William Demarest
John
Julie Adams
Dr. Kay Lambert
Don Haggerty
Harold Hibler
David Janssen
Young Lieutenant
Milburn Stone
Maj. Gen. Wilton J. Ramsey
Nana Bryant
Mother Redempta
Richard H. Cutting
Monsignor Collins
Mary Field
Sister Mary Theresa
Tim Hovey
Cadet Thomas 'Tiger' Flaherty
Tim Considine
Cadet Lt. Gerald Hibler
Sue George
Nancy (uncredited)