Sir Thomas Little Heath (5 October 1861 - 16 March 1940), civil servant and authority on Ancient Greek mathematics. Heath was born at Barnetby-le-Wold, Lincolnshire, England. He graduated from Trinity College, Cambridge, in 1883. Heath started working in the civil service in 1884, working for the Treasury, where he worked at various positions until retiring in 1926.

Far more significant is Heath's work in Ancient Greek mathematics, of which he was the foremost scholar of his time. His books are:

- Diophantus of Alexandia. A study in the history of Greek algebra, 1885, 1910
- Treatise on Conic Sections, Apollonius of Perga, 1896
- The Works of Archimedes, 1897
- The Thirteen Books of Euclid's Elements, 1908, 1926
- Aristarchus of Samos, the ancient Copernicus, 1913
- Greek Astronomy, 1932
- A History of Greek Mathematics, 1921
- A Manual of Greek Mathematics, 1931
- Mathematics in Aristotle, 1949

Heath's most important work is his translation of Euclid's Elements, The Thirteen Books of Euclid's Elements. His translation surpasses every previous edition for clarity and accuracy. Notes, explanations, and appendices make up about 3/4 of the work - Heath makes it very clear why he translated certain things the way he did, and shows how previous translators and scholars approached the same problem. Heath's translation of Euclid's Elements is currently in print as a three volume set from Dover Publications.

Heath also made significant contributions (regarding mathematical terminology) to Liddell and Scott's Greek Lexicon as well as many articles about ancient mathematicians to the 11th edition of the Encyclopædia Britannica.