| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 901 | Molli | Irish | From the Gaelic Maili which is a pet form of Mary 'bitter.'. | M | |
| 902 | Molloy | Irish | Noble chief. | M | |
| 903 | Monohan | Irish | Monk. | M | |
| 904 | Mooney | Irish | Wealthy. | M | |
| 905 | Moore | Irish | Surname. | M | |
| 906 | Morain | Irish | Great. | M | |
| 907 | Moran | Irish | Great. | M | |
| 908 | Morgan | Irish | Fighter of the sea. | M | |
| 909 | Moriarty | Irish | Expert seaman. | M | |
| 910 | Morrissey | Irish | Choice of the sea. | M | |
| 911 | Muircheartaigh | Irish | Expert seaman. | M | |
| 912 | Muireadhach | Irish | Lord of the sea. | M | |
| 913 | Mukonry | Irish | Hound of prosperity. | M | |
| 914 | Mulcahy | Irish | Battle chief. | M | |
| 915 | Mundy | Irish | From Reamon. | M | |
| 916 | Murchadh | Irish | Fighter of the sea. | M | |
| 917 | Murphey | Irish | Seawarrior. | M | |
| 918 | Murphy | Irish | Seawarrior. | M | |
| 919 | Murray | Irish | Lord of the sea. | M | |
| 920 | Murrough | Irish | Fighter of the sea. | M | |