Ezra Joseph Warner III (July 4, 1910 – May 30, 1974) was a historian of the American Civil War. He was born in Lake Forest, Illinois and lived in La Jolla, California where he worked as an investment counselor. He was the son of Ezra J. Warner, Jr. and grandson of Ezra J Warner, who were wholesale grocery business executives in Chicago, Illinois. His father, Ezra J. Warner, Jr., was president & treasurer of wholesale grocery business Sprague, Warner & Company and vice president of the Chicago Orchestral Association. His mother was the former Marion Hall. He is buried in Lake Forest Cemetery in Lake Forest. His great uncle was Union General James M. Warner.