William Kingsland "King" Macy (November 21, 1889 – July 15, 1961) was an American politician from New York.

He engaged in wholesaling and importing from 1912 to 1915, served with the United States Food Administration and War Trade Board from 1917 to 1919, was president of the Union Pacific Tea Co. from 1919 to 1922, was a member of a stock brokerage firm from 1922 to 1938, and was a banker and publisher.

He was active in the investigation of the New York State Banking Department in 1929; and also in promoting the Seabury inquiry into the affairs of New York City in 1931 and 1932.

Macy's hold over the Suffolk Republican party organization was so complete that he was called "The Little King of Suffolk County".

He died on July 15, 1961, in Islip in 1961, and his remains were placed in a receiving vault at Oakwood Cemetery.