William James Hewlett (1876 – 1921) was a British trade unionist and socialist activist. Born in Abertillery, Hewlett became a coal miner and joined the South Wales Miners' Federation. He became interested in syndicalism, and during the Cambrian Combine dispute of 1911, he worked with Noah Ablett, Will Hay and Bill Mainwaring who formed the Unofficial Reform Committee. He was asked to provide feedback on the draft of The Miners' Next Step.