| Name | Color | Sex | Year of birth | Microchip | Sire | Dam | Breed | Breeder |
|---|---|---|---|---|---|---|---|---|
| Thoughtless | f | 1875 | Thoroughbred | |||||
| Thoughtless Beauty | chestnut | f | 1918 | Disguise | Coquette | Thoroughbred | USA | |
| Thousand Words | bay | c | 2004 | Dansili | Verbose | Thoroughbred | Great Britain | |
| Thousand Words | bay | c | 2017 | Pioneerof the Nile | Pomeroys Pistol | Thoroughbred | USA | |
| Thread | bay | f | 1991 | Topsider | Knot | Thoroughbred | USA | |
| Threat | chestnut | c | 2017 | Footstepsinthesand | Flare of Firelight | Thoroughbred | Ireland | |
| Three Dons | chestnut | c | 1960 | Fighting Don | Flowing Lava | Thoroughbred | Great Britain | |
| Three Dress Prom | chestnut | f | 1986 | Perrault | Noble Royalty | Thoroughbred | USA | |
| Three Easy Steps | f | 1980 | An Act | Souix Lynn | Thoroughbred | |||
| Three Fingers | d.-bay | f | 1960 | One Count | Wee Nip | Thoroughbred | USA |