Irish Surnames O
A list of Irish surnames beginning with the letter O. Many Irish surnames have a O’ in front in their Irish version, this list is mainly confined to those names where the O’ is commonly used in the English version of the name.
| Name | Variants | In Irish | Location | Origin |
|---|---|---|---|---|
| O’Brien | Clare, Limerick, very widespread. | Gaelic | ||
| Descendents of Brian Boru, High King of Ireland. | ||||
| O’Callaghan | Callaghan, Callahan | Ó Ceallacháin | Cork, Limerick, widespread. | Gaelic |
| Probably originated from Ceallachan, a 10th century King of Munster. | ||||
| O’Casey | Casey | O Cathasaigh | Gaelic | |
| Means "vigilant". | ||||
| O’Connell | Ó Conaill | Derry, Galway, Kerry widespread, | Gaelic | |
| Very old name. | ||||
| O’Connor | O’Conor, Conner, Connor | Ó Conchobhair, | Clare, Cork, Kerry, Offaly, Roscommon, widespread. | Gaelic |
| Means "hero or champion"; descendents of King Conchobhair of Connacht. . | ||||
| O’Dea | O Deaghaidh | Clar, Cork, Dublin, Limerick, Tipperary | Gaelic | |
| O’Donnell | Ó Domhnaill | Donegal. | Gaelic | |
| Means "world mighty" | ||||
| O’Donovan | Ó Donnabhain | Cork, Kilkenny | Gaelic | |
| Two colours in the name: donn meaning "brown" and dubhann "black". | ||||
| O’Dowd | Dodd, Doody, Duddy | O Dubhda | Galway, Mayo, Sligo | Gaelic |
| Means "black". | ||||
| O’Driscoll | Driscoll. | O hEidersceoil | Cork | Gaelic |
| Means "go between or interpreter". | ||||
| O’Dwyer | Dwyer | O Dubhuidir, | Mayo, Sligo. | Gaelic |
| Means "black shirt". | ||||
| O’Flaherty | Flaherty, O’Flaverty. O’Laverty | Ó Flaithbheartaigh | Galway, Mayo | Gaelic |
| Very ancient family | ||||
| O’Gara | O Gadhra | Cavan, Mayo, Sligo. | Gaelic | |
| Gadhra means "a mastiff " or "dog" | ||||
| O’Gorman | Gorman, Grimes | O Gormain | Clare, Laois, Monaghan. | Gaelic |
| O’Grady | Grady | Ó Grádaigh | Clare, Galway, Limerick. | Gaelic |
| Means "illustrious"; part of the Dalcassian sept and so related to the O’Briens. | ||||
| O’Hagan | Hagan, Aiken | O hAodhagain. Ó hAgain, | Tyrone, Ulster | Gaelic |
| Means "young". | ||||
| O’Halloran | Halloran | O hAllmhurain | Clare, Galway. | Gaelic |
| Means "stranger from over the sea". | ||||
| O’Hara | O hEaghra | Antrim, Sligo | Gaelic | |
| O’Hegarty | Hegerty, Hagerty | O hEigceartaigh | Cork, Derry, Donegal. | Gaelic |
| Means "unjust" | ||||
| O’Higgins | O hUigin | Sligo, Clare, Galway, widespread. | Gaelic | |
| Means "knowledge or ingenuity". | ||||
| O’Keeffe | O’Keefe | Ó Caoinmh | Cork, Limerick | Gaelic |
| Caom means "noble" or "gentle". Also means "descendent of Caoinmh", himeself son of Fionghuine, a King of Munster. | ||||
| O’Leary | Leary | O Laoghaire | Cork | Gaelic |
| Means "calf keeper" | ||||
| O’Malley | Melia | Ó Máille | Mayo | Gaelic |
| Old and distinguished family. The name is derived from "maglios" an ancient Celtic word meaning "chief". | ||||
| O’Meara | Meara, O’Mara, Mara | O Meadhra, | Tipperary, widespread. | Gaelic |
| Means "mirth". | ||||
| O’Neill | Neill, Nihill | Antrim, Down, Tyrone, widespread. | Gaelic | |
| Very old and prestigious family. Neill means "champion". | ||||
| O’Reilly | Reilly, Riley, O’Rahilly | Ó Raghailligh | Cavan, widespread | Gaelic |
| Ragheallach means "gregarious race" | ||||
| O’Riordan | Riordan, Reardon. | O Riordáin | Cork, Tipperary. | Gaelic |
| Means "royal bard". | ||||
| O’Rourke | Roark, Rooke, Rourke, Rorke | Ó Ruairc | Cavan, Leitrim. | Norse |
| Originates from the Norse-Viking name Hrothrekr, who married into the Irish. | ||||
| O’Shaughnessy | Shaughnessy | O Seachnsaigh | Clare, Galway, Limerick. | Gaelic |
| O’Shea | Shea, Shee | Ó Séaghdha, Ó Sé | Kerry, Kilkenny. | Gaelic |
| Means "stately or majestic" and also "dauntless". One of the merchant families of Kilkenny. | ||||
| O’Sullivan | Sullivan | Ó Súileabháin | Cork, Kerry, Tipperary. | Gaelic |
| Means "one-eyed" or "hawk-eyed". | ||||
| O’Toole | Toal, Tool, Toole, Toohill, Twohill. | Ó Tuathail | Kildare, Wicklow, widespread. | Gaelic |
| Descendents of Tuathal, a 10th century King of Leinster. Means "mighty or prosperous people" | ||||
I notice with some dismsy that O’Haire is not listed! I can only presume that it si a derivation of another. In gaelic it is Mac an Aodhaoire son of shepherd! How did it become O’Haire
Our name in the Gaelic was originally O’ Faodhagain. Translates into Fagan here. Somewhere along the line it changed to the “Figgins” of today. Please, where do I start research on the name? Are there websites, books or libraries in Ireland that you could recommend? Thank you.
My last name is Driotes, some how it has been deformed, according to our family records, our grand grand father came from Europe so the last known last name was Driottiz or Driotez somebody can help me?
I notice you have Dwyer/O’Dwyer name coming from Mayo/Sligo but it is from Kilnamanagh in Tipperary. I am a Dwyer from this part of the country. The biggest number of Dwyer/O’Dwyer (900+) families currently live there. This is where the Dwyer/O’Dwyer castles are also located, which were destroyed during the Cromwellian settlements.
Hi.
I have looked at your list of surnames,but I can’t find mine,Mulvey. My father was Irish from Tipperary,so I Am presuming it was an Irish surname,appreciate it if you had any information at all about its origins.
Regards
S Mulvey.
It is indeed an Irish surname, and not an uncommon one. I don’t know a lot about it, but it is a name of Gaelic origin, in Irish it would be Ó Maoilmhiadhaigh – which I bet looks kind of unpronounceable! ‘Mwale (rhymes with ale) – vade- ig’ would be there or thereabouts. I see from a quick search online that there is a general consensus that the comes from the Irish ‘Maidach, meaning honourable. I kind of don’t think that’s quite right. My Irish isn’t brilliant, but I’ve not heard that word – which definitely doesn’t mean it does not exist! Maybe it’s old Irish, or maybe just unknown to me.
The fist part ‘Maoil’ means ‘follower of’, so I’d be inclined to go for the second part as being a person’s name, a leader of some kind. Maybe his name meant honourable, or perhaps he was an honourable person and that’s where this came from.