William Averell Harriman (November 15, 1891 ??July 26, 1986) was an American Democratic politician, businessman, and diplomat. He was the son of railroad baron E. H. Harriman. He served as Secretary of Commerce under President Harry S. Truman and later as the 48th Governor of New York. He was a candidate for the Democratic presidential nomination in 1952, and again in 1956 when he was endorsed by President Truman but lost to Adlai Stevenson both times.

Harriman served President Franklin D. Roosevelt as special envoy to Europe and served as the U.S. Ambassador to the Soviet Union and U.S. Ambassador to Britain. He served in numerous U.S. diplomatic assignments in the Kennedy and Johnson Administrations. He was a core member of the group of foreign policy elders known as 'The Wise Men'.