Encyclopedias, Almanacs, Transcripts, and Maps
- Thorfinn Karlsefni Thordarson
- Thorny-Headed Worms: Acanthocephala
- Thorogood, Brackett K(irkwood) (1881-1965)
- Thought-Reading
- Thought-Transference
- Thoughtforms
- Thouless, Robert Henry (1894-1984)
- Thrashers and Mockingbirds: Mimidae
- Three Gorges Dam
- Three-Mile Island
- Three-Toed Toadlets: Brachycephalidae
- Three-Toed Tree Sloths: Bradypodidae
- Thrips: Thysanoptera
- Thrombasthenia of Glanzmann and Naegeli
- Thrombasthenia of Glanzmann and Naegeli
- Thrushes
- Thrushes
- Thrushes and Chats: Turdidae
- Thule Society
- Thurston, Herbert Henry Charles (S. J.) (1856-1939)