Ernest Joseph King (23 November 1878 – 25 June 1956) was an American naval officer who served as Commander in Chief, United States Fleet (COMINCH) and Chief of Naval Operations (CNO) during World War II. As COMINCH-CNO, he directed the United States Navy's operations, planning, and administration and was a member of the Joint Chiefs of Staff. He was the United States Navy's second most senior officer in World War II after Fleet Admiral William D. Leahy, who served as Chief of Staff to the Commander in Chief.

Born in Lorain, Ohio, King served in the Spanish–American War while still attending the United States Naval Academy. He received his first command in 1914, leading the destroyer USS Terry in the occupation of Veracruz. During World War I, he served on the staff of Vice-Admiral Henry T. Mayo, the commander of the United States Atlantic Fleet. After the war, King served as head of the Naval Postgraduate School, commanded a submarine squadron, and served as Chief of the Bureau of Aeronautics. After a period on the Navy's General Board, King became commander of the Atlantic Fleet in February 1941.

Shortly after the Japanese attack on Pearl Harbor, King was appointed as Commander in Chief of the United States Fleet. In March 1942, King succeeded Harold Stark as Chief of Naval Operations. In December 1944, King became the second admiral to be promoted to fleet admiral. King left active duty in December 1945 and died in 1956.