| Xan | Galician | Xian, Xoan |
| Xanthus | Greek | Golden-haired. |
| Xanti | Basque | |
| Xavier | Arabic/Spanish | Arabic: Bright. Spanish: Of the new house. |
| Xenophon | Greek | Strange voices, or strong sounding. |
| Xenos | Greek | A stranger. |
| Xerxes | Persian | A king or ruler. The name of a famous Persian king. |
| Xiao | Galician | |
| Ximen | Spanish | Spanish form of Simon. The listener. |
| Ximenes | Spanish | Spanish form of Simon. The listener. |
| Ximens | Spanish | Spanish form of Simon. The listener. |
| Ximun | Basque | Basque form of Simon. |
| Xurxo | Galician | |
| Xylon | Basque | Basque form of Simon. |