William Gillis (10 November 1859 – 18 September 1929) was a British politician. Born on a ship in the Black Sea, Gillis grew up in Gressenhall in Norfolk. He moved to the West Riding of Yorkshire and became active in the Yorkshire Miners' Association (YMA) and the Labour Party. He was elected to Hoyland Nether Urban District Council and served for a time as its chairman. He stood in the Penistone by-election, 1921, gaining the seat for Labour, but was defeated at the 1922 general election, and did not stand again. Following his stint in Parliament, he worked for the YMA and became a magistrate.