William Mellor (1888–1942) was a left-wing British journalist.Mellor joined the Daily Herald in 1913 as a journalist, and was imprisoned during the First World War as a conscientious objector, returning to the Herald on his release. A Guild Socialist during the 1910s, he worked closely with G. D. H. Cole, founding the National Guilds League with him in 1915. He was a founder-member of the Communist Party of Great Britain in 1920, but resigned in 1924.