| Liandan | Woman | Irish Names |
| Lir | Man | Irish Names |
| Lochlyn | Unisex | Irish Names |
| Lorcan | Man | Irish Names |
| Lugh | Man | Irish Names |
| Lynn | Unisex | Irish Names |
| Lyons | Unisex | Irish Names |
| Mab | Woman | Irish Names |
| Madadh | Woman | Irish Names |
| Madden | Unisex | Irish Names |
| Madigan | Unisex | Irish Names |
| Maeve | Woman | Irish Names |
| Magee | Man | Irish Names |
| Mahon | Man | Irish Names |
| Mahoney | Unisex | Irish Names |
| Maili | Woman | Irish Names |
| Maire | Woman | Irish Names |
| Mairead | Woman | Irish Names |
| Majella | Woman | Irish Names |
| Malone | Man | Irish Names |