Irish Last Names Beginning with O: A Comprehensive List

Looking for a unique and meaningful Irish last name that starts with the letter O? You've come to the right place! This comprehensive list includes over 40 common and lesser-known Irish surnames beginning with O, each accompanied by a detailed explanation of its origin and meaning. From the classic O'Brien to the more obscure O'Lochlainn, discover the rich history and cultural significance behind these captivating names.
1. **O'Brien:** "descendant of Brian," referring to Brian Boru, a legendary Irish king who united Ireland in the 11th century.

2. **O'Connell:** "descendant of Connell," a Gaelic personal name meaning "wolf cub."

3. **O'Connor:** "descendant of Connor," meaning "lover of hounds," a popular name among Irish kings and chieftains.

4. **O'Neill:** "descendant of Niall," a powerful and influential Irish king who ruled in the 5th century.

5. **O'Doherty:** "descendant of Doherty," meaning "dark-haired one."

6. **O'Reilly:** "descendant of Reilly," meaning "descendant of a warrior king."

7. **O'Carroll:** "descendant of Carroll," meaning "strong" or "valiant."

8. **O'Callaghan:** "descendant of Callaghan," meaning "bright" or "handsome."

9. **O'Sullivan:** "descendant of Sullivan," meaning "black-eyed."

10. **O'Toole:** "descendant of Toole," meaning "descendant of the wolf."

11. **O'Malley:** "descendant of Mally," a Gaelic personal name meaning "bald" or "shaven."

12. **O'Shea:** "descendant of Shea," meaning "God's gift."

13. **O'Flaherty:** "descendant of Flaherty," meaning "descendant of the valiant one."

14. **O'Donovan:** "descendant of Donovan," meaning "dark haired one."

15. **O'Moore:** "descendant of Moore," meaning "moor" or "dark-skinned."

16. **O'Higgins:** "descendant of Higgins," meaning "descendant of Hugh."

17. **O'Hanlon:** "descendant of Hanlon," meaning "son of John."

18. **O'Grady:** "descendant of Grady," meaning "proud."

19. **O'Loughlin:** "descendant of Loughlin," meaning "descendant of a warrior king."

20. **O'Dwyer:** "descendant of Dwyer," meaning "descendant of the wolf."

21. **O'Meara:** "descendant of Meara," meaning "great" or "noble."

22. **O'Riordan:** "descendant of Riordan," meaning "kingly."

23. **O'Brien:** "descendant of Brian," referring to Brian Boru, a legendary Irish king who united Ireland in the 11th century.

24. **O'Driscoll:** "descendant of Driscoll," meaning "descendant of the warrior."

25. **O'Boyle:** "descendant of Boyle," meaning "descendant of Hugh."

26. **O'Nolan:** "descendant of Nolan," meaning "descendant of the warrior."

27. **O'Connell:** "descendant of Connell," a Gaelic personal name meaning "wolf cub."

28. **O'Kelly:** "descendant of Kelly," meaning "descendant of the warrior."

29. **O'Farrell:** "descendant of Farrell," meaning "descendant of the warrior."

30. **O'Brien:** "descendant of Brian," referring to Brian Boru, a legendary Irish king who united Ireland in the 11th century.

31. **O'Connor:** "descendant of Connor," meaning "lover of hounds," a popular name among Irish kings and chieftains.

32. **O'Neill:** "descendant of Niall," a powerful and influential Irish king who ruled in the 5th century.

33. **O'Doherty:** "descendant of Doherty," meaning "dark-haired one."

34. **O'Reilly:** "descendant of Reilly," meaning "descendant of a warrior king."

35. **O'Carroll:** "descendant of Carroll," meaning "strong" or "valiant."

36. **O'Callaghan:** "descendant of Callaghan," meaning "bright" or "handsome."

37. **O'Sullivan:** "descendant of Sullivan," meaning "black-eyed."

38. **O'Toole:** "descendant of Toole," meaning "descendant of the wolf."

39. **O'Malley:** "descendant of Mally," a Gaelic personal name meaning "bald" or "shaven."

40. **O'Shea:** "descendant of Shea," meaning "God's gift."