John Sidney McCain, Sr. (9 August 1884 - 6 September 1945) was an Admiral in the United States Navy, notable as a commander of the Fast Carrier Task Force in World War II. His son John S. McCain, Jr. was also an admiral (the only father-son pair of full admirals in US history), and his grandson John McCain III a senator from Arizona.

McCain was born in Teoc, Mississippi , and graduated from the Naval Academy in 1906 after attending a few years at the University of Mississippi. His first assignments were on ships of the Asiatic Squadron. During the American occupation of Veracruz in the Mexican revolution he served in San Diego, and remained on the ship during 1918 while she performed Atlantic escort duty.

In the years between the world wars, McCain served in many ships, including Maryland, New Mexico, and Nitro . His first command was the Sirius . In 1936, at the age of 51, he was designated a Naval Aviator, and from 1937 to 1939 he commanded the aircraft carrier Ranger, contributing much to the development of carrier tactics for the war to come. For the first year of World War II he served as Commander of Air Forces for Western Sea Frontier and the South Pacific Force. In October 1942 McCain became Chief of the Bureau of Aeronautics and in August 1943 rose to the rank of Vice Admiral as Deputy Chief of Naval Operations (Air).

In 1944 he returned to the Pacific Theater, succeeding Marc Mitscher as commander of the Fast Carrier Task Force, which for over a year operated almost continuously in support of the great amphibious operations. McCain's exceedingly skillful tactics protecting Canberra (CA-70) and Houston (CA-81) in October 1944 earned him the Navy Cross, and the daring forays of his mobile force had much to do with the eventual victory.

Vice Admiral McCain died in September 1945, just after arriving back in the United States, and was posthumously appointed Admiral effective that date. He was buried in Arlington National Cemetery. For his outstanding performance as an air planner and carrier task force commander he was awarded the Distinguished Service Medal with two Gold Stars; Secretary James Forrestal commented: "He was a fighting man all the way through."