William Halsey, Jr., American admiral (d. 1959)
William Frederick Halsey Jr. (October 30, 1882 – August 16, 1959) was a fleet admiral in the United States Navy during World War II. He is one of four individuals to have attained the rank of fleet admiral of the United States Navy, the others being Ernest King, William Leahy, and Chester W. Nimitz.

Born in Elizabeth, New Jersey, Halsey graduated from the United States Naval Academy in 1904. He served in the Great White Fleet and, during World War I, commanded the destroyer USS Shaw. He took command of the aircraft carrier USS Saratoga in 1935 after completing a course in naval aviation, and was promoted to the rank of rear admiral in 1938. At the start of the War in the Pacific (1941–1945), Halsey commanded the task force centered on the carrier USS Enterprise in a series of raids against Japanese-held targets.

Halsey was made commander of the South Pacific Area, and led the Allied forces over the course of the Battle for Guadalcanal (1942–1943) and the fighting up the Solomon chain (1942–1945). In 1943 he was made commander of the Third Fleet, the post he held through the rest of the war. He took part in the Battle of Leyte Gulf, the largest naval battle of the Second World War and, by some criteria, the largest naval battle in history. He was promoted to fleet admiral in December 1945 and retired from active service in March 1947.