William Ewart Humphrey (March 31, 1862 – February 14, 1934), an American politician, served as a member of the United States House of Representatives from 1903 to 1917. He represented the state of Washington at large from 1903 to 1909 and the First Congressional District of Washington from 1909 to 1917. Humphrey also served as a member of the Federal Trade Commission from 1925 to 1933.