Top 25 Irish Last Names
and Their Meanings

There are over 3500 Irish last names. There's no way I'll cover them all on this page. I'll begin with the 25 most common surnames. Maybe your name will be on the list. None of my family names are on the top 25 list. Only one made it in the top 100. I'll add these at the end. The amateur genealogist in me is making me do it. That and the fact I'm kind of proud of my family history.

First off, Irish last names are messed up. You can blame the English for this. In the seventeenth century the English invaded and colonized Ireland. In order to bend the Irish to their rule, the English made Gaelic sounding names illegal. Anglicising of Irish last names led to some confusion. The Mac, Mc and O were dropped along with other changes. The name MacAodhagain (Egan) became Keegan. The name MacMathghamhna (MacMahon) became Vaughan. Many other Irish last names were changed during this period.

In the nineteenth century these discriminatory laws began to ease up. The native people began to show their individuality by adding back the prefix Mac and O to their Irish last names. They added them to the anglicised form of their name. Thus Donnell became O'Donnell from the old Gaelic O'Domhnaill. Many, many others followed this same pattern.

The following list will give the modern Irish last names, the Gaelic equivalent, the meaning and their county of origin. This list will begin with the most common Irish last names on down.

One other thing before I start. Irish family groups are called septs not clans.

On to the Irish last names list.

1. Murphy (o Murchadha) "sea warrior" There were several septs in Tyrone, Slingo, Wexford and some in Cork.

2. Kelly (o Ceallaigh) "bright headed" This sept came into being in a least seven different places on the island. The two largest being in Galway (once called Ui Maine) and Meath. Others are from Dublin, Kildare, Roscommon, Antrim and Derry.

3. O'Sullivan (o Suilleabhain) "hawk eyed" Tipperary was the original territory of this sept. As they grew they moved into Cork and Kerry.

4. Walsh (Breathnach) "Welshman" There is no common ancestor for this family. The name was used for the hundreds of Welshmen that came with the Normans in the 12th century. The name appears mostly in Mayo. Other large numbers can be found in Galway, Cork, Wexford, Waterford and Kilkenny.

5. Smith (Mac an Ghaghain) "son of the smith" Other forms of this name include MacGowan and O'Gowan. The MacGowan sept originated in County Cavan. They can also be found in Leitrim, Donegal and Sligo.

6. O'Brian (o Briain) "high, noble" This sept is primarily from Clare and Limerick.

7. Byrne (o Broin) "raven" This sept started out in Kildare. They were driven south to Wicklow by the Anglo-Normans in the 11th century.

8. Ryan (o Maoilriain) "king" This sept can be divided into two main branches. The o Riains from Carlow and the o Maoilriains from Tipperary and Limerick.

9. O'Connor (o Conchobhair) "hero, champion" This name was most predominate in the counties in western Ireland. Today this sept is most common in Kerry, with
Cork and Limerick following.

10. O'Neill (o Neill) "from Niall of the Nine Hostages" This sept was divided into two main branches. The senior branch from County Tyrone is considered extinct. The junior branch is from Counties Antrim and Down.

11. O'Reilly (o Raghallaigh) I can't find a meaning for this name. The O'Reilly sept centered around County Cavan. Their influence extended into Meath and Westmeath also.

12. Doyle (o Dubhghaill) "dark foreigner" This sept is assumed to be descended from Norsemen. This explains their high concentration on the southeast coast especially in Wexford.

13. McCarthy (Mac Carthaigh) "loving person" This sept is most prevalent in County Cork. The famous Blarney Castle was built by the McCarthys. Cormac McCarthy lived in the castle at the time he was avoiding submission to Queen Elizabeth's rule. He did so by writing evasive answers to her letters demanding he submit. Thus began the legend of "kissing the Blarney Stone". Doing so would endow a person with the gift of evasive and eloquent speech.

14. Gallagher (o Gallchobhair) "lover of foreigners" They were one of the main septs of Donegal. They were marshalls in the amry of the O'Donnells.

15. O'Doherty (o Dochartaigh) "hurtful" This sept originated in County Donegal.

16. Kennedy (o Cinneide) "helmet headed" This sept started out in County Clare. Later the O'Briens and MacNamaras forced them to Tipperary where the name is still popular today.

17. Lynch (o Loinsigh) "mariner, seafarer" This sept settled in Clare, Slingo and Limerick. There was also a branch in Donegal.

18. Murray (o Muireadhaigh) "lord, master" Most of this sept is of Scot descent. They settled in the counties of the northwest in the Province of Ulster. There was one important sept from County Roscommon.

19. Quinn (o Cuinn) "wisdom, chief" County Tyrone is the place of origin of one of the septs of this name. It is still very common there today. Counties Clare, Antrim and Longford are other places this sept came from.

20. Moore (o Mordha) "noble" This sept was centered in County Leix or Laois as it is called today.

21. McLoughlin (Mac Lochlainn) "viking" One branch of this sept originated in County Donegal. The name is found mostly in Counties Donegal and Derry today. The other sept believed to be extinct, was from Meath.

22. O'Carroll (o Cearbhaill) "valorous in battle" The two most important septs were from Tipperary and Offaly. Other
minor septs of the name were from Monaghan and Louth.

23. Connolly (o Conghaile) "fierce as a hound" There are three distinct septs of the name from the Counties of Cork, Meath and Monaghan.

24. Daly (o Dalaigh) "assembles frequently" This sept originated in County Meath.

25. O' Connell (o Conaill) "strong as a wolf" The O' Connells were strong in the Province of Munster. The sept was also found in Counties Galway and Londonderry.

Now for some of my family names.

Duff (o Dufaigh) "dark, black" This sept was found mostly in Louth, Monaghan and Armagh. The name is believed to be derived from the Name Duffin.

Leech (o Laoghogh) "physician" The sept may have originated in Donegal and Londonderry. Today this name is found mostly in Galway and Clare.

Keenan (o Cianain) "ancient, enduring" This sept came from the Counties of Fermanagh, Monaghan and Louth. My Great Grandfather came from County Down to the U. S. in 1883.

Kerrigan (o Ciaragain) "black" There are two main branches for this sept. One from County Donegal the other from County Mayo. My Great Grandmother came to America in 1896 from County Westmeath.

O'Donnell (o Domhnaill) "world mighty" The stronghold of the O'Donnell sept was in County Donegal. Two minor septs were in Counties Galway and Clare.

The above is obviously a very short list of Irish last names. Use the search box below for more names.


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One last note if you are interested in your family crest. I hate to break it to you. But, there is really no such thing as a family crest for your family's Irish last name. They are awarded to people on an individual basis. They can be passed down from father to son. They are not awarded to a "family name" as a whole. A Grant of Arms can still be granted by the Chief Herald at the National Library of Ireland.

With that being said a family crest with Irish last names still makes a cool looking decoration, even if it was only awarded to a possible ancestor with your Irish last name.


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