Obrien

An Irish surname of Dublin and Galway. In the 2010 US census it was carried by 118,557 people, the 258th most common surname in the country.

Obrien is the anglicised form of two distinct Irish names. Some you can hear in the English name; others look and sound nothing like it, and were simply swapped for it.

Brian, son of Brian (a common Breton personal name introduced into England at the Conquest). This family stood in Co. Kilkenny and Co. Wexford.

Ó Briain, descendant of Brian. This family stood in Co. Clare, Co. Limerick, Co. Tipperary, and Co. Waterford.

Where the name comes from

Ó Briain descends from Brian Boru, King of Ireland, who was slain at Clontarf in the year 1014. By his victories over the Danish invaders and their Irish allies, Brian raised his clan, the Ui Toirdealbhaigh, to a position of pre-eminence among the Dalcassians and laid the foundation of the greatness of his posterity.

They became not only the ruling family in Thomond but one of the most powerful in Ireland; some of them were kings of Munster and some of all Ireland. Their possessions included the whole of Co. Clare and large portions of Limerick, Tipperary and Waterford.

They divided into several branches: the O'Briens of Ara in the north of Co. Tipperary, whose chief was known as Mac I Bhriain Ara; of Coonagh in the east of Co. Limerick; and of Pobelbrien, now the barony (an old land division, several parishes across) of that name in Co. Limerick.

There is also a plain Brian, son of Brian, a common Breton personal name introduced into England at the Conquest, whose family settled in Kilkenny and Wexford.

Moonlight reflecting on the sea near the Muglins lighthouse off Dalkey Island, Dublin, with the Kish light on the horizon
The Muglins by Moonlight II

The Obrien counties, photographed

Dublin

Dublin is a county as well as a city. The bay has Howth at the north end and Killiney Hill at the south, the Muglins are a pair of rocks off Dalkey, and the Dublin Mountains start about half an hour from the city centre.

Long exposure panoramic view of the White Rock swimming platform at Killiney Bay, Dublin, floating in misty high-tide watersThe White Rock, Killiney Bay, Co. Dublin Co. Dublin Heron fishing at dawn on the Dublin coast — fine art wildlife photograph by Peter CoxHeron, Co. Dublin Co. Dublin

Galway

Connemara takes up the west of the county: the Twelve Bens, blanket bog, and fields walled off into very small squares. The Aran Islands sit at the mouth of Galway Bay. The Gaeltacht starts a few miles west of Galway city.

Enormous waves sending spray over 30-metre sea cliffs at Poll an tSeidein on Inis Meain, Aran Islands at sunsetPoll an tSéideáin, Inis Meáin, Aran Islands, Co. Galway Co. Galway The rusting Plassey shipwreck on Inis Oirr, Aran Islands, seen from above with the Atlantic Ocean beyondThe Plassey, Inis Oirr, Aran Islands, Co. Galway Co. Galway Dramatic storm waves battering tall cliffs at sunset on the west coast of Inis Meain, Aran IslandsPoll an tSéideáin Panoramic, Inis Meáin, Aran Islands, Co. Galway Co. Galway Turf drying at sunset with Connemara mountains in the background, Co. Galway, Ireland, fine art landscape photograph by Peter CoxConnemara Turf, Co. Galway Co. Galway Dramatic light slicing through a stormy Connemara landscape on the road towards Leenaun village, County GalwayThe Road to Leenaun, Co. Galway Co. Galway Mweelrea from the Inagh Valley, Co. GalwayMweelrea from the Inagh Valley, Co. Galway Co. Galway Ewe and lamb grazing by the road with Lough Nafooey and mountains in the background, Joyce Country, GalwayLough Nafooey and Sheep, Co. Galway Co. Galway The Maumturk Mountains in Connemara lit by dramatic sunlight on a stormy day, County GalwayThe Maumturks, Co. Galway Co. Galway Aerial view of Slyne Head twin lighthouses on rocky outcrops with Atlantic waves crashing around them, GalwaySlyne Head, Co. Galway Co. Galway

All Dublin prints · All Galway prints

Notable bearers

Conan O'Brien (born 1963), film actor, television actor, and writer.

Dylan O'Brien (born 1991), actor, model, and YouTuber.

Edna O'Brien (1930-2024), writer, screenwriter, and novelist.

Edmond O'Brien (1915-1985), actor, film producer, and director.

Ed O'Brien (born 1968), musician, composer, and songwriter.

About this page

The counties on this page are where the name was thickest on the ground in Ireland a century and a half ago, not a claim about any one family. Names moved around inside the country as much as they left it. The photographs are mine, made in the counties named.

More Irish surnames: Johnson · Collins · Murphy · Howard · Coleman · Hayes · Mason · Palmer · Warren · Ryan · Lane · Franklin

How common the name was

In 1890, 602 births were registered under Obrien in Ireland, most of them in Cavan, Dublin, and Galway.

Munster 291
Leinster 105
Ulster 56
Connacht 50
Ireland 602

Cavan is the one I haven't worked in.