William Weir (June 1868 – December 1926) was a British trade unionist. Born in Mickley Square, Northumberland, Weir studied at Prudhoe Colliery School and then worked at West Wylam Colliery from the age of twelve. He soon became active in the Northumberland Miners' Association, and was elected branch president in 1905, then to the county executive in 1912. In 1914, he became President of the union, serving until 1926.