Thoreau MacDonald (April 21, 1901 at Toronto, Ontario – May 30, 1989 at Toronto) was a Canadian illustrator, designer and painter.
MacDonald was the son of Group of Seven member J. E. H. MacDonald. He was mainly self-taught, but he did work with his father. MacDonald was colour blind and as a result he worked primarily in black and white.
As an illustrator, MacDonald worked for the Ryerson Press and Canadian Forum magazine. His work is found in the National Gallery of Canada in Ottawa, Hart House at the University of Toronto, the Art Gallery of Ontario, and the McMichael Canadian Art Collection amongst other collections.
His former home and 4-acre (16,000 m2) garden in Vaughan, Ontario, which he inherited from his father, was donated to the City of Vaughan in 1974. The building and grounds have been restored and are open to the public.