| Thomas Hart Clay | |
| Minister From: | United States |
| Country: | Honduras |
| Term Start: | April 5, 1864 |
| Term End: | August 10, 1866 |
| Predecessor: | James R. Partridge |
| Successor: | Richard H. Rousseau |
| Minister From2: | United States |
| Country2: | Nicaragua |
| President2: | Abraham Lincoln |
| Term Start2: | January 15, 1863 |
| Term End2: | May 31, 1863 |
| Predecessor2: | Andrew B. Dickinson |
| Successor2: | Andrew B. Dickinson |
| Office3: | Member of the Kentucky House of Representatives from Fayette County |
| Term Start3: | 1859 |
| Term End3: | 1861 |
| Birth Date: | 22 September 1803 |
| Birth Place: | Lexington, Kentucky, U.S. |
| Death Place: | Lexington, Kentucky, U.S. |
| Resting Place: | Lexington Cemetery |
| Father: | Henry Clay |
| Education: | Transylvania University |
Thomas Hart Clay (September 22, 1803 – March 18, 1871) was the U.S. ambassador to Honduras and Nicaragua.[1] He was a son of Henry Clay.