Theodore Sturgeon was an American fiction author of primarily fantasy, science fiction, and horror, as well as a critic. He wrote approximately 400 reviews and more than 120 short stories, 11 novels, and several scripts for Star Trek: The Original Series.

Theodore Tilton was an American newspaper editor, poet and abolitionist. He was born in New York City to Silas Tilton and Eusebia Tilton. On his twentieth birthday, October 2, 1855, he married Elizabeth Richards. Tilton's newspaper work was fully supportive of abolitionism and the Northern cause in the American Civil War.

Major Theodore Woolsey Winthrop was a writer, lawyer, and world traveller. He was one of the first Union officers killed in the American Civil War.

Pierre Jules Théophile Gautier was a French poet, dramatist, novelist, journalist, and art and literary critic.

Theophrastus was a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos. His given name was Τύρταμος (Túrtamos); his nickname Θεόφραστος (Theóphrastos) was given by Aristotle, his teacher, for his "divine style of expression".

Thomas Adolphus Trollope was an English writer who was the author of more than 60 books. He lived most of his life in Italy creating a renowned villa in Florence with his first wife, Theodosia, and later another centre of British society in Rome with his second wife, the novelist Frances Eleanor Trollope. His mother, brother and both wives were known as writers. He was awarded the Order of Saints Maurice and Lazarus by Victor Emmanuel II of Italy.

Thomas Allibone Janvier was an American story-writer and historian, born in Philadelphia of Provençal descent.

Thomas Anstey Guthrie was an English author, most noted for his comic novel Vice Versa about a boarding-school boy and his father exchanging identities. His reputation was confirmed by The Tinted Venus and many humorous parodies in Punch magazine.

Thomas Arnold was an English educator and historian. He was an early supporter of the Broad Church Anglican movement. As headmaster of Rugby School from 1828 to 1841, he introduced several reforms that were widely copied by other noted public schools. His reforms redefined standards of masculinity and achievement.

Thomas Bailey Aldrich was an American writer, poet, critic, and editor. He is notable for his long editorship of The Atlantic Monthly, during which he published writers including Charles W. Chesnutt. He was also known for his semi-autobiographical book The Story of a Bad Boy, which established the "bad boy's book" subgenre in nineteenth-century American literature, and for his poetry.