U.S.-Canadian industrialist and philanthropist, founder of the Republic Steel Corporation (1930).

While a student, Eaton was persuaded by John D. Rockefeller to forego joining the ministry and become a businessman instead. Starting in business in 1907, he had built several electric power plants in western Canada within a few years, and he soon diversified into other utilities, banking, and steel in the United States. He was a relentless consolidator of the many companies that at one time or another came under his control. In 1930 he amalgamated several steel companies that he owned into Republic Steel Corporation, which was the third largest steel company in the United States. Eaton lost most of his fortune in the Great Depression but subsequently made a second one with his activities in the securities industry, banking, and railroads.

Eaton became prominent in the 1950s and '60s as an advocate of nuclear disarmament and improved U.S.-Soviet relations. In 1957 he was one of the inaugurators of the Pugwash Conferences (originally held at his lodge in Nova Scotia), at which leading scientists and scholars from various countries met to exchange views and promote international understanding. At Eaton's death his fortune was estimated at about $200,000,000.