Old Irish Last Names: A Guide to Their Origins and Meanings

Are you interested in tracing your Irish heritage through your last name? Old Irish last names offer a window into the history and culture of Ireland, often revealing fascinating insights into the lives and origins of your ancestors. From ancient Gaelic clan names to Anglicized versions, these surnames hold a wealth of meaning and symbolism, providing a unique connection to the Emerald Isle. Explore this list of common and less-known old Irish last names and discover the captivating stories behind their origins.
1. **Ó Briain:** "Descendant of Brian", referring to the legendary King Brian Boru, a powerful warrior-king who united Ireland in the 11th century.
2. **Ó Néill:** "Descendant of Niall", a powerful dynasty that ruled over much of Ireland in the medieval period.
3. **Ó Conaill:** "Descendant of Connell", a Gaelic clan name with origins in County Donegal.
4. **Ó Dálaigh:** "Descendant of Dálach", a name that may have originated from the word for "meadow" or "valley".
5. **Ó Ceallaigh:** "Descendant of Ceallach", meaning "bright" or "vigorous".
6. **Ó Cróinín:** "Descendant of Cróinín", possibly a diminutive form of "Cróin" meaning "crown".
7. **Ó Súilleabháin:** "Descendant of Súilleabháin", a name that means "bright-eyed" or "keen-sighted".
8. **Ó Murchú:** "Descendant of Murchú", meaning "sea warrior" or "sea king".
9. **Ó Fearghaíl:** "Descendant of Fearghal", meaning "man of strength" or "mighty warrior".
10. **Ó Maolchathaigh:** "Descendant of Maolchathach", a name that means "bald" or "shaven".
11. **Ó Cléirigh:** "Descendant of Cléirigh", meaning "clerk" or "scribe".
12. **Ó hUiginn:** "Descendant of Uiginn", a name that means "descendant of Óengus".
13. **Ó Caoimh:** "Descendant of Caoimh", meaning "gentle" or "handsome".
14. **Ó Cathasaigh:** "Descendant of Cathasaigh", meaning "battle-leader" or "warrior".
15. **Ó Laoghaire:** "Descendant of Laoghaire", a name that means "calf" or "young bull".
16. **Ó hAinmhire:** "Descendant of Ainmhire", meaning "noble" or "eminent".
17. **Ó Ciardha:** "Descendant of Ciardha", a name that means "dark" or "black".
18. **Ó Maolchonaire:** "Descendant of Maolchonaire", a name that means "bald" or "shaven".
19. **Ó Séaghdha:** "Descendant of Séaghdha", meaning "victor" or "conqueror".
20. **Ó Rathaille:** "Descendant of Rathaille", a name that means "fort" or "castle".
21. **Ó Ciosáin:** "Descendant of Ciosáin", meaning "small" or "little".
22. **Ó Ríordáin:** "Descendant of Ríordáin", a name that means "kingly" or "royal".
23. **Ó Coileáin:** "Descendant of Coileáin", meaning "little dog" or "puppy".
24. **Ó Conchúir:** "Descendant of Conchúir", a name that means "hound" or "wolf".
25. **Ó Duibhir:** "Descendant of Duibhir", a name that means "dark" or "black".
26. **Ó Gallchóir:** "Descendant of Gallchóir", a name that means "foreign" or "stranger".
27. **Ó Flannagáin:** "Descendant of Flannagáin", a name that means "red" or "ruddy".
28. **Ó Nuallain:** "Descendant of Nuallain", meaning "noble" or "famous".
29. **Ó Donnchadha:** "Descendant of Donnchadha", a name that means "brown" or "dark".
30. **Ó Luain:** "Descendant of Luain", a name that means "light" or "bright".
31. **Ó Corráin:** "Descendant of Corráin", meaning "strong" or "brave".
32. **Ó hÉigeartaigh:** "Descendant of hÉigeartaigh", meaning "leader" or "chieftain".
33. **Ó Cadhlaigh:** "Descendant of Cadhlaigh", meaning "handsome" or "beautiful".
34. **Ó Domhnaill:** "Descendant of Domhnaill", a name that means "world" or "universe".
35. **Ó Machaigh:** "Descendant of Machaigh", meaning "warlike" or "battle-loving".
36. **Ó Dúill:** "Descendant of Dúill", meaning "black" or "dark".
37. **Ó Maoileacháin:** "Descendant of Maoileacháin", a name that means "bald" or "shaven".
38. **Ó Faolain:** "Descendant of Faolain", meaning "wolf cub" or "young wolf".
39. **Ó Meachair:** "Descendant of Meachair", meaning "merchant" or "trader".
40. **Ó Mathghamhna:** "Descendant of Mathghamhna", a name that means "bear" or "powerful".