Thomas Hartmann or Hartman may refer to:
- Thomas de Hartmann (1885–1956), Russian composer and associate of George Ivanovitch Gurdjieff
- Thomas Hartmann (biologist) (1937–2017), German pharmaceutical biologist and ecologist
- Thomas W. Hartmann, 2nd Legal Adviser to the Convening Authority in the Department of Defense Office of Military Commissions
- Thom Hartmann (born 1951), American broadcaster and author
- Thomas Hartman (scientist), faster-than-light theoretician, discoverer of the Hartman effect
- Monsignor Tom Hartman, co-host of The God Squad
- Tom Hartman, a character on the American soap opera parody Mary Hartman, Mary Hartman
- Thomas Hartmann (footballer) (born 1967), Swiss football striker