William Thompson (22 January 1862 – 6 October 1937) was an Australian politician.
He was born in Queanbeyan to surveyor James Banford Thompson and Margaret Carroll. From 1878 to 1885 he was a clerk in the Colonial Architect's office, before becoming a quantity surveyor and moving to Ryde in 1898. On 4 March 1885 he had married Florence Single, with whom he had two children. He owned a horse farm on the Hawkesbury River and was a founder of the William Thompson Masonic School at Baulkham Hills NSW, which operated from 1922 to 1972, and the New South Wales Masonic Schools Welfare Fund which, as A Start in Life, continues to assist indigent youth. He was a Freemason and Grand Master of the Grand Lodge of New South Wales 1914-1924. In 1913 he was elected to the New South Wales Legislative Assembly as the Liberal member for Ryde, serving until his retirement in 1920. Thompson died at Ashfield in 1937.