John S. McCain Sr., American admiral (b. 1884)
John Sidney "Slew" McCain (August 9, 1884 – September 6, 1945) was a U.S. Navy admiral and the patriarch of the McCain military family. He held several command assignments during the Pacific campaign of World War II. McCain was a pioneer of aircraft carrier operations. Serving in the Pacific Ocean theater of World War II, in 1942 he commanded all land-based air operations in support of the Guadalcanal campaign, and in 1944–45 he aggressively led the Fast Carrier Task Force. His operations off the Philippines and Okinawa and air strikes against Formosa and the Japanese home islands caused tremendous destruction of Japanese naval and air forces in the closing period of the war. He died four days after the formal Japanese surrender ceremony.

Several of McCain's descendants also graduated from the United States Naval Academy. He and his son, John S. McCain Jr., were the first father–son pair to achieve four-star admiral rank in the U.S. Navy. His grandson, John S. McCain III, served as a Navy captain in the Vietnam War, and later served in Congress until his death in 2018. His great-grandsons, John S. McCain IV and James McCain, currently serve in the U.S. Navy and U.S. Marine Corps, respectively.