Thomas Maxwell Harris FRS (born 8 January 1903; died 1983) was a British botanist.
He was educated at Bootham School, York.
He received his doctorate from the University of Cambridge and was a Fellow of the Royal Society. He served as President of the Linnean Society of London from 1961 to 1964.
- The Fossil Flora of Scoresby Sound East Greenland (Copenhagen, 1931).
- The British Rhaetic Flora (London, 1938).
- British Purbeck Charophyta (London, 1939).
- Liassic and Rhaetic Plants collected in 1936-38 from East Greenland, etc. (Copenhagen, 1946).
- Conifers of the Taxiodiaceæ from the Wealden Formation of Belgium, etc. (Brussels, 1953).
- The Yorkshire Jurassic flora (five volumes, London, 1961–1979).