John Sidney "Slew" McCain Sr. (August 9, 1884 – September 6, 1945) was a United States Navy admiral. He held several command assignments during the Pacific campaign of World War II. His son was John S. McCain, Jr. and his grandson is John McCain.
McCain, Sr. was born on August 9, 1884 in Carroll County, Mississippi. He studied at the University of Mississippi and at the United States Military Academy at West Point. McCain, Sr. was married to Catherine Davey Vaulx from 1909 until his death in 1945. They had one child. McCain died on September 6, 1945 in Coronado, California from a heart attack, aged 61.