John Grimes Walker (March 20, 1835 – September 16, 1907) was an admiral in the United States Navy who served during the Civil War. After the war, he served as Chief of the Bureau of Navigation, head of the Lighthouse Board, and commander-in-chief of the Squadron of Evolution and of the North Atlantic Squadron. In retirement, he led commissions to investigate the construction of a Central American canal connecting the Atlantic and Pacific Oceans.