Thomas Harris (born 1940) is an American author.
Thomas Harris may also refer to:
- Thomas Harris (Serjeant-at-Law) (1547–1610), English politician, MP for Truro, Callington, Portsmouth and Bossiney
- Thomas Harris (died 1622), MP for Maldon
- Thomas Harris (died 1628) (1550–1628), MP for Shrewsbury
- Thomas K. Harris (died 1816), US congressman from Tennessee
- Thomas L. Harris (1816–1858), U.S. Representative from Illinois
- Thomas Harris (mayor) (1817–1884), Canadian mayor of Victoria, British Columbia
- Thomas R. Harris (1836–1894), political figure in Nova Scotia, Canada
- Thomas Alexander Harris (1826–1895), Confederate politician & Missouri State Guard (Confederate) general
- Thomas Harris (Irish politician) (1895–1974), Irish politician
- Thomas Harris (architect) (1829–1900/30–1900), British architect
- Thomas Harris (diplomat) (1945–2021), British diplomat and banker
- Thomas Harris (surgeon) (1784–1861), U.S. Navy surgeon
- Thomas Harris (theatre manager) (died 1820), English theatre manager
- Thomas Anthony Harris (1910–1995), American psychiatrist
- Thomas Lake Harris (1823–1906), American spiritualist
- Thomas Allen Harris, founder and President of Chimpanzee Productions
- Thomas Maxwell Harris (1903–1983), British botanist
- Thomas Bradley Harris (1826–1866), American businessman and co-founder of the American colony of "Ellena"
- Thomas Spencer Harris (1836–1893), California newspaperman
- Thomas Britton Harris IV (born 1958), chief investment officer of the University of Texas Investment Management Company
- Tomás Harris (1908–1964), UK Security Service officer during World War II