William Dodd Hathaway (born February 21, 1924) is an American politician from Maine. He was elected to the U.S. House as a Democrat and served in that body from 1965 to 1973; he also served as a member of the U.S. Senate from 1973 to 1979. Hathaway was first elected to the House in 1964 with 62% of the vote. He defeated incumbent U.S. Senator Margaret Chase Smith (R) with 53% of the vote in 1972, but was himself defeated for reelection in 1978 with 34% of the vote by Republican Congressman Bill Cohen.