| Theirn | | - | French | |
| Thelma | | THEL-mə | English | |
| Themistocles | | - | Ancient Greek (Latinized) | |
| Themistokles | | - | Ancient Greek | |
| Theo | | THEE-o (English), TAY-o (Dutch) | English, Dutch | |
| Theobald | | THEE-ə-bawld (English) | English (Rare), Ancient Germanic | |
| Theocritus | | - | Ancient Greek (Latinized) | |
| Theoderich | | - | Ancient Germanic | |
| Theodoar | | - | Ancient Germanic | |
| Theodoard | | - | Ancient Germanic | |
| Theodora | | thee-ə-DAWR-ə (English) | English, Greek, Ancient Greek | |
| Theodore | | THEE-ə-dawr | English | |
| Theodoricus | | - | Ancient Germanic (Latinized) | |
| Theodoros | | - | Greek, Ancient Greek | |
| Theodorus | | - | Ancient Greek (Latinized), Dutch | |