If your family tree carries an Irish surname — O’Brien, MacNamara, Clancy, Hickey, or any of the other great names that rose from the limestone heart of Thomond — then County Clare may well be where your story begins. The Irish surnames from Clare are among the oldest and most historically resonant in Ireland. They belong to a world of Dalcassian warriors, hereditary physicians, poet-lawyers, and sea-lords who shaped the Kingdom of Thomond for five centuries. To carry one of these names is to carry that history with you across generations and oceans.
This guide covers thirteen of the most significant Clare surnames — their Gaelic origins, their meanings, the baronies and townlands they called home, and how they made their way to America. Whether you are beginning your research or deepening it, understanding the surname itself is the first step toward finding the place your ancestors left behind. For broader guidance on how to begin tracing your Irish roots, see our full guide to finding your Irish ancestry.
The Kingdom of Thomond: Understanding Clare’s Surname Heritage
County Clare sits at the centre of what was once the Kingdom of Thomond (Tuathmhumhan, “North Munster”), a Gaelic kingdom that endured from before the Viking age until the Elizabethan conquest of the sixteenth century. Its founding dynasty, the Dál gCais — the Dalcassians — produced Brian Boru, High King of Ireland, and gave rise to almost every major Clare clan. This single tribal grouping is the common ancestor of O’Brien, MacNamara, O’Dea, McMahon, Moloney, Hickey, and dozens of other Clare families.
For genealogical purposes, Clare is divided into nine baronies: Bunratty, Burren, Clonderlaw, Corcomroe, Ibrickane, Inchiquin, Islands, Moyarta, and Tulla. These administrative units are the framework for all major Irish record sets — Griffith’s Valuation (1855), the Tithe Applotment Books (1820s–1840s), and the 1659 Census. Knowing which barony your ancestors came from is the key that unlocks the archive.
Irish Surnames from Clare: Origins and Meanings
O’Brien (Ó Briain) — The Royal Blood of Thomond
Of all the Irish surnames from Clare, O’Brien stands as the most powerful. The name means “descendant of Brian” — specifically Brian Boru, High King of Ireland, who died at the Battle of Clontarf in 1014 having defeated the Viking alliance. The O’Briens ruled the Kingdom of Thomond for five centuries after Clontarf, making them one of the longest-lasting Gaelic dynasties in Irish history.
Their territory covered all of Clare, centred on the Baronies of Inchiquin, Bunratty, and Tulla. Their ancient inauguration site was Magh Adhár, between Ennis and Tulla — a sacred mound where kings were crowned for centuries. Dromoland Castle, near Newmarket-on-Fergus, was an ancestral O’Brien seat and is now a luxury hotel; its grounds still hold the emotional weight of those eight hundred years. American O’Briens emigrated in vast numbers during the Famine, settling in New York, Boston, and Pennsylvania. The name today is so widespread in the United States that parish-level Clare documentation is essential to confirm a specific ancestral county.
MacNamara (Mac Conmara) — The Hound of the Sea
Mac Conmara means “son of the hound of the sea” — from mac (son), cú (hound), and na mara (of the sea). The MacNamaras were the second most powerful Dalcassian family in Thomond, serving as hereditary marshals to the O’Briens and holding the privilege of inaugurating the O’Brien chief as king.
By 1370, the clan had divided into two branches: MacNamara Fionn (“fair”) in the Barony of Bunratty, and MacNamara Riabhach (“swarthy”) in the Barony of Tulla. Between them, the MacNamaras are credited with building some of Clare’s most enduring monuments — Bunratty Castle, Knappogue Castle, and the magnificent Quin Friary, which stands largely intact today. Post-Famine McNamaras emigrated primarily through Limerick port and Liverpool, settling in New York, Boston, and Philadelphia.
O’Dea (Ó Deaghaidh) — Lords of Dysart
The O’Deas were lords of Dysart O’Dea in the Barony of Inchiquin — and their place-name still dominates the local landscape in the townlands of Dysart O’Dea, Curragh O’Dea, and Tully O’Dea. Their most celebrated moment came on 10 May 1318, when clan chief Conchobhar Ó Deaghaidh defeated and killed the Norman lord Richard de Clare at the Battle of Dysert O’Dea, effectively ending Norman ambitions in Thomond for nearly two centuries.
The site of the battle — Dysart O’Dea Castle, built circa 1490 — still stands and now houses the Clare Archaeology Centre. It was purchased and restored in 1970 by an Irish-American named John O’Day, a Wisconsin businessman who crossed the Atlantic to reclaim his family’s ancestral ground. That story, of a diaspora heir returning to buy back the ruined seat of his clan, is one of the most quietly extraordinary heritage stories in County Clare.
O’Loughlin (Ó Lochlainn) — Lords of the Burren
Ó Lochlainn means “descendant of Lochlann” — a Norse-derived word meaning “Land of the Lakes,” used by the Irish to refer to Scandinavia. The name reflects Ireland’s long centuries of Viking contact and the way Norse personal names filtered into Gaelic use. The O’Loughlins were lords of the Barony of Corcomroe, the limestone upland we now call the Burren, and their four sea-facing castles at Gleninagh, Ballyvaughan, Shanmuckinish, and Muckinishroe defined the western edge of their territory.
Genealogists note that the O’Loughlin surname is almost exclusively Clare in origin, making it one of the more geographically reliable Clare surnames for research purposes. A direct descendant, Sir Bryan O’Loghlen, became Prime Minister of Victoria, Australia in the 1880s — a reminder that the Clare diaspora reached far beyond America. The Burren, with its extraordinary limestone pavements and ancient ring forts, is the most intact O’Loughlin landscape in Ireland.
Quinn / O’Quinn (Ó Cuinn) — Lords of Inchiquin
Ó Cuinn means “descendant of Conn” — from a root word implying wisdom, counsel, or leadership. The Clare Quinns were a Dalcassian sept whose territory of Muintir Ifernain centred around Corofin in north-west Clare. The Barony of Inchiquin itself derives its name from this family — “Inchiquin” meaning “island/district of the Quinns.” One member of the sept, Niall Ó Cuinn, reportedly died at the Battle of Clontarf in 1014, fighting beside Brian Boru.
A critical research note: Quinn is the nineteenth most common surname in all of Ireland, with major unrelated septs in Tyrone, Longford, and Mayo. Clare-specific Quinn ancestry requires geographic verification through parish records — particularly for the Corofin and Inchiquin barony area. Do not assume Clare origin on the strength of the name alone.
McMahon (Mac Mathaú) — The Clare Bears of the West
Mac Mathaú means “son of the bear” — from mathghamhan, the Irish word for bear. The Clare McMahons were a distinct Dalcassian sept — lords of Corca Bhaschind in the Baronies of Moyarta and Clonderlaw in south-west Clare — entirely unrelated to the Ulster McMahons of County Monaghan. This distinction is essential: if your McMahon family comes from the parishes of Kilmihil, Kilkee, Kilrush, or anywhere along the west Clare coast, they are almost certainly of the Thomond sept.
The Clare McMahons fell with many other Thomond clans at the Battle of Kinsale (1602). Many subsequently joined the Wild Geese — the Irish soldiers who entered the service of Catholic European powers, chiefly France. Their alabaster McMahon Tomb (1460), depicting scenes from the Passion, survives in Ennis Friary and is one of the finest pieces of medieval Irish sculpture in existence. West Clare Famine emigrants departed primarily through Kilrush, on the Shannon Estuary, and through Limerick city.
Moloney / Molony (Ó Maol Dhomhnaigh) — Devotees of the Church
The Moloney name means “descendant of the devotee of the church” — from maol (the tonsured clerical practise of early Irish monasticism) and domhnach (Sunday, or church). The Moloneys were chiefs of Coiltenain — modern Kiltannon — in the Barony of Tulla, and their castles at Rinnua and Coolistigue marked their east Clare heartland. Place-names preserving the family survive in Ballymoloney and Feenagh (Moloney) in County Clare.
Two members of the Kiltannon sept became Bishops of Killaloe; another, Father Donogh O’Molony, was tortured to death for his faith in 1601, making him the earliest recorded individual to bear this name in the Clare Library’s genealogical records. The Cromwellian settlement (1650s) dispossessed many Moloneys from their Tulla estates, beginning the long dispersal that would accelerate dramatically during the Famine.
Clancy (Mac Fhlannchaidh) — Keepers of the Law
Mac Fhlannchaidh means “son of the red warrior” — from flann (red) and cath (warrior/battle). The Clare Clancys were a branch of the MacNamara family who served as hereditary brehons — the judges and legal scholars — of the O’Brien kings. Their homeland was the Barony of Corcomroe in north Clare, and the townland of Cahermaclanchy in Killilagh parish still preserves their name.
In Gaelic Ireland, the brehon lawyers occupied a position of enormous honour and influence. The Clancys maintained the oral and written legal tradition of Thomond, adjudicating disputes, recording inheritances, and codifying the rights of every class of society. After the defeat of the Jacobite cause in 1691, many Clancys followed the Wild Geese to France. The 1911 Census records 653 Clancys born in Clare, confirming it as one of the primary origin counties. Note that an entirely separate and unrelated Clancy sept existed in County Leitrim.
Hickey (Ó hÍcidhe) — Healers to Kings
The Hickey name derives from iceadh, meaning “healer,” making this one of the few Irish surnames that directly encodes a professional role. The O’Hickeys were the hereditary physicians to the O’Brien kings of Thomond, renowned across medieval Ireland for their medical knowledge — including the surgical technique of trepanning, using silver plates to repair skull fractures. Their home territory was Ballyhickey near Quin in the Barony of Bunratty.
The family’s scholarly legacy is remarkable. Nicholas Ó hÍceadha (d. 1403) co-authored a commentary on the Aphorisms of Hippocrates — a fragment survives in the British Museum. Donnchad Óg Ó hÍceadha (d. 1489) translated European surgical texts into Irish, an astonishing act of medical scholarship in an era of Gaelic cultural siege. The Book of the O’Hickeys, a medical manuscript, is held in the National Library of Ireland in Dublin. Post-Famine Hickeys emigrated to New York, Boston, and Philadelphia.
O’Hehir (Ó hAichir) — Voice of Clare
Ó hAichir means “descendant of Aichear” — the personal name interpreted as “fierce” or “sharp.” The O’Hehirs were a Dalcassian sept originally seated at Magh Adhár — the O’Brien inauguration site — and they always assisted at the coronation ceremony, signifying their close alignment with the paramount dynasty. Over time they settled in the Barony of Islands in west-central Clare.
The most famous modern bearer of the name was Micheál O’Hehir (1920–1996), the legendary broadcaster whose distinctive commentary on RTÉ from 1938 to 1985 shaped how generations of Irish people — at home and in the diaspora — experienced the drama and passion of Irish cultural life. His voice became synonymous with the great occasions that united the country, and his contribution to Irish broadcasting remains unmatched. Post-Famine O’Hehirs settled primarily in New York and Boston.
Slattery (Ó Slatara) — The Strong Ones of Tulla
The Slattery name comes from slatra, meaning “robust,” “strong,” or “bold.” The sept originated at Ballyslattery near Tulla, in the Barony of Upper Tulla, east Clare — and the name remains most concentrated in east Clare, north Tipperary, and Limerick. As a Dalcassian sept, the Slatterys were supporters of the MacNamaras and participated in the wars of Thomond. The name is today most numerous in the United States, concentrated in New York, California, and Massachusetts.
O’Halloran (Ó hAllmhuráin) — The Ones from Across the Sea
Ó hAllmhuráin means “descendant of Allmhurán” — from allmhurach, meaning “foreigner from overseas” or “stranger from across the sea.” It is an evocative name for a clan that would eventually cross that same sea in their millions. The Clare O’Hallorans were a Dalcassian clan based in Ogonnelloe, on the shores of Lough Derg in the Barony of Tulla. A separate and entirely unrelated O’Halloran sept existed in County Galway — researchers must confirm geographic origin before assuming Clare ancestry.
O’Grady (Ó Grádaigh) — The Noble Ones
Ó Grádaigh means “descendant of Grádach” — from gradach, meaning “noble” or “illustrious.” The O’Gradys were chiefs of Kineál Donghuile in the Barony of Lower Tulla, aligned with O’Brien supremacy throughout the medieval period. Their motto, Vulneratus Non Victus — “Wounded But Not Defeated” — speaks to the resilience of a family that survived the Cromwellian wars, the Penal Laws, and the Famine.
An important research note: a branch of the O’Grady family adopted the name Brady in the late sixteenth century to avoid Penal Law discrimination — Brady families in east Clare may have O’Grady origins. The family produced two cousins of literary significance: Standish Hayes O’Grady (1832–1915), a scholar of early Irish history, and Standish James O’Grady (1846–1928), whose popular novels of Irish legend made him a key figure in the Celtic Revival.
How Clare’s Names Crossed the Atlantic
The Great Famine (1845–1852) was catastrophic for County Clare. The population fell from approximately 286,000 in 1841 to around 212,000 in 1851 — a loss of over 74,000 people in a single decade through death and emigration. Today’s population stands at roughly 127,000, less than half the pre-Famine figure. No county in Connacht or Munster experienced a more complete demographic collapse.
Clare emigrants departed primarily through Kilrush on the Shannon Estuary, through Limerick city, and through Liverpool, where many thousands first crossed the Irish Sea before boarding transatlantic ships. Their principal American destinations were New York (particularly the Five Points neighbourhood and later the Bronx and Brooklyn), Boston, Philadelphia, and New Haven, Connecticut. Between 1845 and 1854, over $19 million was remitted from Irish-Americans back to Ireland, much of it in the form of prepaid tickets — meaning that within a decade, nearly every Clare townland had family connections in specific American cities.
The most famous Clare-born figure to make that crossing was John Philip Holland (1841–1914) of Liscannor, who emigrated to Boston in 1873 and went on to invent the first modern submarine formally commissioned by the US Navy. Less famous, but more numerous: the tens of thousands of tenant farmers — O’Briens, McMahons, MacNamaras, Moloneys — who crossed knowing they would likely never return, holding in memory the name of the townland they left behind.
Where to Research Your Clare Ancestry
The primary resource for Clare genealogy is the Clare Heritage and Genealogy Centre in Corofin — the longest-established genealogy centre in Ireland, founded in 1982. It holds parochial registers from all 47 parishes in County Clare, civil records, Griffith’s Valuation, Tithe Applotment Books, census returns, cemetery records, and emigration lists. Records are also searchable at RootsIreland.ie/clare.
The Clare County Library Genealogy Pages (clarelibrary.ie/eolas/coclare/genealogy) provide free online access to surname indices for all major record sets. The 1901 and 1911 Census returns for Clare are fully searchable at census.nationalarchives.ie — these are the most accessible household-level records in Irish genealogy and will often give you a townland for a specific family within minutes of searching.
If your Clare connection comes from a specific surname, cross-reference the barony table below with Griffith’s Valuation to identify the parishes where that surname was concentrated. Once you have a townland, you can locate it on the modern map using the Placenames Database of Ireland (logainm.ie) and plan a visit to the landscape your ancestors knew. For planning that visit in detail, our guide to planning an Irish heritage trip covers everything from archives to ancestral townland visits. And if you are driving in rural Clare — as you almost certainly will be — our guide to renting a car in Ireland from the USA is essential preparation.
Heritage Sites to Visit in County Clare
Ennis Friary — Founded between 1240 and 1249 by the O’Brien kings, the friary holds one of the finest collections of medieval Irish sculpture in existence, including the McMahon Tomb (1460) with its alabaster Passion scenes.
Dysart O’Dea Castle (Clare Archaeology Centre, near Corofin) — The restored seat of the O’Dea clan, on the site of the great 1318 battle. The archaeological complex also includes a Round Tower and High Cross from the monastery of Saint Tola, founded around 700 AD.
Magh Adhár (between Ennis and Tulla) — The ancient inauguration site of the O’Brien kings of Thomond. A modest mound in a field, unremarkable to a passing motorist but profoundly significant to anyone who knows the history. Accessible to visitors.
Quin Abbey — Built by the MacNamara Fionn sept in the fifteenth century, incorporating the walls of an earlier Norman castle. One of the best-preserved medieval Franciscan friaries in Ireland.
Corcomroe Abbey (the Burren) — A Cistercian abbey founded circa 1194, associated with the O’Brien and O’Loughlin families, containing an effigy tomb of Conor O’Brien, King of Thomond (d. 1267).
Killaloe / Kincora — On the River Shannon, the ancient seat of the Dál gCais and Brian Boru. The twelfth-century St. Flannan’s Cathedral and the Killaloe Heritage Centre offer an accessible entry point into the world the Dalcassian clans built.
For context on how these heritage surnames spread across other counties, see our guides to Irish surnames from Cork, Irish surnames from Galway, Irish surnames from Kerry, and Irish surnames from Dublin.
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Frequently Asked Questions About Irish Surnames from County Clare
What are the most common Irish surnames from County Clare?
The most historically significant surnames from County Clare include O’Brien, MacNamara, O’Dea, O’Loughlin, Quinn, McMahon, Moloney, Clancy, Hickey, O’Hehir, Slattery, O’Halloran, and O’Grady. Almost all are of Dalcassian origin, descending from the Dál gCais tribal grouping that dominated the Kingdom of Thomond from the ninth century onwards. O’Brien is by far the most numerous, but the more geographically specific Clare surnames — such as O’Loughlin (almost exclusively Burren) and O’Hehir (Islands and Inchiquin baronies) — are often more useful for genealogical research.
What does the name MacNamara mean in Irish?
MacNamara comes from the Irish Mac Conmara, meaning “son of the hound of the sea.” The elements are mac (son), cú (hound), and na mara (of the sea). The name originates with the Dalcassian chieftain Cumara, whose descendants adopted the hereditary surname from the eleventh century. The MacNamaras were hereditary marshals to the O’Brien kings and are credited with building Bunratty Castle, Knappogue Castle, and Quin Friary.
How do I trace my Clare ancestry if I only know the county?
Start with the 1901 and 1911 Census returns at census.nationalarchives.ie — these are free, fully searchable, and will often give you a specific townland for a Clare family. Cross-reference with Griffith’s Valuation (1855) to establish where a family was living in the pre-Famine period. The Clare Heritage and Genealogy Centre in Corofin holds parochial registers for all 47 Clare parishes and can provide professional research services. Once you have a townland, use logainm.ie to locate it on a modern map. Our complete guide to finding your Irish ancestry walks through every stage of this process.
Are there two different McMahon families in Ireland?
Yes — and the distinction is critical for genealogical research. The Clare McMahons were a Dalcassian sept, lords of Corca Bhaschind in the Baronies of Moyarta and Clonderlaw in south-west Clare. The Monaghan McMahons were an entirely separate and unrelated sept, rulers of the Kingdom of Oriel in south Ulster. If your McMahon family comes from the parishes of Kilmihil, Kilkee, Kilrush, or the west Clare coast, they are almost certainly of the Clare Thomond sept. If from County Monaghan or south Ulster, they are of the Oriel sept. Never assume a shared origin on the strength of the name alone.
Is the O’Brien family originally from Clare?
Yes — the O’Brien dynasty is rooted in County Clare, descending from Brian Boru of the Dál gCais, whose seat was at Kincora near Killaloe on the River Shannon. The family’s ancient inauguration site, Magh Adhár, lies between Ennis and Tulla in east Clare. After Brian’s death at the Battle of Clontarf in 1014, his descendants ruled the Kingdom of Thomond — centred on Clare — for approximately five centuries. However, because O’Brien became one of the most widespread surnames in Ireland over those centuries, not every American O’Brien family has Clare roots — Limerick, Tipperary, and Waterford also have significant O’Brien populations. Parish-level research is essential to confirm a specific Clare origin.
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