| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 641 | Lesley | Gaelic | From the gray fortress. | M | |
| 642 | Leslie | Gaelic | From the gray fortress. | F | |
| 643 | Leslie | Gaelic | From the gray fortress. | M | |
| 644 | Liam | Gaelic | Helmeted. | M | |
| 645 | Liosliath | Gaelic | From the gray fortress. | M | |
| 646 | Liusaidh | Gaelic | Warrior. | F | |
| 647 | Logan | Gaelic | From the hollow. | M | |
| 648 | Loghan | Gaelic | From the hollow. | M | |
| 649 | Lon | Gaelic | Fierce. | M | |
| 650 | Lonn | Gaelic | Fierce. | M | |
| 651 | Lucas | Gaelic | Light. | M | |
| 652 | Luthais | Gaelic | Famous in battle. | M | |
| 653 | Mac | Gaelic | Son of. Scottish and Irish surname prefix sometimes used as a given name or nickname. Mack: (Scottish) Ancient Scottish given name. | M | |
| 654 | Mac a'bhaird | Gaelic | Son of Baird. | M | |
| 655 | Mac a'bhiadhtaiche | Gaelic | Son of Bhiadhtaiche. | M | |
| 656 | Mac Adhaimh | Gaelic | Son of Adam. | M | |
| 657 | Mac Ailean | Gaelic | Son of the handsome man. | M | |
| 658 | Mac Alasdair | Gaelic | Son of Alasdair. | M | |
| 659 | Mac an Aba | Gaelic | Son of the Father or Abbott. | M | |
| 660 | Mac an Bharain | Gaelic | Son of the noble warrior. | M | |