William Douw Lighthall KC FRSL FRSC (December 27, 1857 - August 3, 1954), often referred to as W. D. Lighthall, was a Canadian lawyer, historian, novelist, poet and philosopher. He served as mayor of Westmount from 1900 to 1903. During that time he originated, and in 1901 co-founded, the Union of Canadian Municipalities (now the Federation of Canadian Municipalities). He also served as vice president of the National Municipal League of America. In 1915 he founded Canada's first veterans' group, the Canadian Association of Returned Soldiers. Lighthall was a member of the International Congress of Philosophy. He published in the Philosophical Review three times in the late 1920s.