| Teague | Man | Irish Names |
| Teige | Man | Irish Names |
| Tiergan | Man | Irish Names |
| Tierna | Woman | Irish Names |
| Tiernan | Man | Irish Names |
| Tierney | Unisex | Irish Names |
| Tieve | Woman | Irish Names |
| Tigernach | Unisex | Irish Names |
| Tighearnach | Man | Irish Names |
| Torin | Man | Irish Names |
| Torrin | Unisex | Irish Names |
| Tremayne | Unisex | Irish Names |
| Trory | Man | Irish Names |
| Tully | Unisex | Irish Names |
| Turlough | Unisex | Irish Names |
| Tynan | Unisex | Irish Names |
| Tyran | Unisex | Irish Names |
| Tyrone | Man | Irish Names |
| Uaine | Unisex | Irish Names |
| Úna | Woman | Irish Names |