In This Site

In This Section


O'Brien/O'Bryant/Brien/Bryant ( ó Briain)

The clan of Brian Boru.

From the tenth century, when the sept rose to the High Kingship of Ireland in the person of Brian Boru, down to the present day, the O'Briens have always been prominent in the history of the country. Before Brian Boru's time, the Dalcassian clan, known as the Ui Toirdealbhaigh, to which they belonged, was not of outstanding importance in Thomond: the greatness of Brian gave them pre-eminence there and in due course the sept, which took the surname O'Brien from him, divided Into several branches and possessed a great part of Munster, of which they were frequently kings.

The O'Briens of Ara (north Tipperary), a territory they acquired from the O'Donegans about the year 1300 had as chief Mac Ui Bhriain Ara; those of Co. Limerick gave their name to the barony of Pubbelebrien; another branch was located around Aherlow by the Galtees; and another south of the Comeragh Mountains on the rich lands near Dungarvan. In all those areas, and especially in Co. Clare they are numerous to-day: the name, in fact, is so common that it comes sixth in the statistical list relating to Irish surnames, with an estimated population of more than thirty thousand persons. In this connexion it may be observed, that though fifty years ago one third of the people of the name was registered as plain Brien, nowadays it is rarely to be found without the prefix O.

The outstanding figure is, of course, Brian Boru (941 - 1014), whose remarkable career as High King of Ireland ended with his death on the field of the battle of Clontarf when the Norsemen were finally subdued. Brian, in fact used no surname; it was, however, in regular use forty years after his death. According to Eleanor Hull's History of Ireland the first O'Brien to adopt the surname was Donagh Cairbre (1194-1242), son of Donal, who submitted to Henry II., From 1055 to 1616. The last year recorded by the Four Masters, O'Briens figure in the annals of every generation, over 300 individuals of the name finding a place in that great work. In the "Annals of Innisfallen", which deal principally with the southern half of Ireland, the O'Briens appear more often than any other sept. Murrough O'Brien (d. 1551) was the first Earl of Thomond; Murrough of the Burnings (d. 1674) was sixth Baron Inchiquin. The descendants of Brian Boru, in the main line, have been peers of the realm under three titles, Earls and Marquises of Thomond, Barons and Earls of Inchiquin and Viscounts Clare. The two former have more often than not been on the side of England, notably Murrough O'Brien, first Earl of Thomond (d. 1551), who was one of the great Gaelic chiefs to acknowledge Henry VIII, and the other notorious Murrough O'Brien, sixth Baron Inchiquin (1614-1674) whose exploits during the war of 1641-1650 earned him the sobriquet "Murrough of the Burnings".

The Viscounts Clare, on the other hand, present a different picture; the first of these, Daniel O'Brien (1577-1663), was a member of the Supreme Council of the Catholic Confederates; it was the third Viscount, also Daniel O'Brien (d.1690), who raised the famous Irish Brigade regiment known as Clare's Dragoons, which was later commanded in many famous battles on the continent by the fifth Viscount, Charles O'Brien, whose distinguished military career ended when he was killed at the battle of Ramillies in 1706, while his son, Charles O'Brien, sixth Viscount (1699-1771), upheld the family tradition at Dettingen and Fontenoy, and became a Marshal of France.

The above is taken from Go Ireland site.


Connections exist from the 1500s between Butlers and O'Briens.

William and Catherine's son was Pierce O'Brien Butler d 1812
His son was Edmund O'Brien Butler d 1877
His son was Murrough (Morgan) O'Brien Butler who came to America and dropped the 'O'Brien' to become Morgan Butler, alive in 1859.
So he may be the link whereby many of the name Butler have Type III haplotypes.

A member of the Type III cluster, Bruce Butler, is descended from a William Butler b 1720 Isle of Wight Co VA USA, who presumably was also Type III. William Butler's birth predates the marriage of William O'Brien-Butler of Bansagh (Bansha) recorded in the Irish Genealogist as occurring in 1763, so if this marriage date can be relied upon, the crossover ancestor from the O'Briens, if this indeed was the source of the Butler Type III yDNA, must have been somewhat earlier. Now the marriage of Morgan O'Brien Butler has been discovered they may be the parents of William Butler of Isle of Wight, VA USA.

Crow(e) (McEnchruadh) (MacEnchroe)

The very English-looking name Crowe disguises the genuinely Irish surname MacEnchroe, which in its original form is Mac Conchradha. Woulfe states that the form MacEnchroe is still in use; but all the members of this sept who live in its original territory, viz. Thomond, are certainly called simply Crowe. The sept was subordinate to that of O'Dea and was located in the western part of the present barony of Inchiquin. The great majority of Crowes either hail from Clare and Tipperary or are of families which migrated to Dublin and other large urban centers from that area. The name is fairly numerous in Belfast but most of these are presumably of British planted stock, Crowe being quite a common name in England. The old form MacEnchroe was that usually used in the transplantation certificates of the 1650's. In one or two cases the form MacCrowe was used. It is preserved in the motto "Skeagh mac en chroe" attached to the coat of arms of the Clare Crowes. It is interesting to note that there is a place-name near Mount Callan in Co. Clare called Skaghvicencrowe which means the thorn bush of MacEncroe. Some branches of the Crowe sept used a thorn bush as the main charge in their arms. The old form was still used in Co. Tipperary in the last century, eg. by the family of Rev. John McEnroe (1795-1868), who, as well as being the founder of the Freeman's Journal of Sydney, is noteworthy for his edition of Donlevy's Catechism. Dermot MacEncroe (fl. 1730), author of many beautiful poems in Latin, was of a French family which had emigrated from Co. Clare and used de la Croix as a French form of MacEncroe. The best known Irish Crowe was O'Beirne Crowe of Cong, Co. Galway, who though according to tradition he was stupid and ill-educated as a boy, became one of the first professors in the Queen's College (now University College) Galway, and was in the first rank of Gaelic scholars. Eyre Evans Crowe (1799-1868), the historian and novelist, was an Irishman, and his son, Sir Joseph Archer Crowe (1825-1896) - who was, however, reared in England - was also a man of note as a diplomat, art critic and war correspondent.

The above is reproduced from http://www.goireland.com/genealogy/family.htm?FamilyId=115


- (Nancy Custer Dorcey Group Administrator)

The Type III Irish group (Lineage IV in the Dorsey Project), I suspect, may indeed have come lately to the name. There are only two members in the group. One of the members uses the Dorcey spelling and one the D'Arcy. They were unknown to each other prior to joining the project. They cannot identify a common ancestor though they both trace back to Tipperary in the mid-1800's. Apparently there was a period of time when those of Darcy/Dorcey/Dorchaidhe/etc origins aspired to be Norman (around the late 1700's, I think) and adopted the D'Arcy spelling to go with their R1b Irish Y chromosomes. Incidentally, more and more of the Irish (non E3b) D'Arcys are dropping the apostrophe and assuming more indigenous spellings - Darcy, Dorcey, etc - most of which derive from O'Dorchaidhe.

(O) Hara

- (William O'Hara R-L226)

Bill has found that his 3rd Great Grandparents were O'Hehir and were so for three generations living in Limerick City.

Edward MacLysaght says of O'Hehir:
O'Hehir O'Hegher Ó hAichir (aichear, bitter sharp). The name of a Dalcassian sept which is numerous in Cos. Clare and Limerick: some are probably of Ui Fidhgheinte origin, rare elsewhere.

(O) Hogan

- (Edward MacLysaght - Irish Families)

The Hogans are a Dalcassian family, their eponymous ancestor being Ógan who was descended from an uncle of Brian Boru, the most celebrated of all Kings of Ireland. The Dalcassian territory extended well beyond the boundaries of Co. Clare which was the heart of Thomond, their country. The Hogans occupied the extreme north-eastern part of it and their chief lived at Ardcrony, near Nenagh, Co. Tipperary. The name is numerous in Ireland, being among the hundred commonest surnames. The great majority of the eight thousand or so persons so called (which is the estimate of the present Hogan population) belong toto their original native habitat, being found today in Co. Tipperary, Clare and Limerick. Fr. Joh Ryan states that the O Hogans of north Tipperary were of the Muscraíghe and distinct from the Dalcassian Hogans of Co. Clare. There are also a number in Co. Cork, whose origin is stated by O'Donovan to be different from the Dalcassian Hogans. One of the minor Corca Laoidhe septs was O'Hogan. In Irish the name is Ó hÓgáin but the prefix O is only occasionally met with in the modern form in English. In the seventeenth century the name was often written Ogan. There is a placename Ballyhogan in the parish of Dysart, Co. Clare.

McGrath/McGraw/McCraw (Mac Craith)

- (Michael McGraw)

The origins of the McGrath of Co. Clare and descent from Echtighern, son of Cennedi and brother of Brian Boru, is detailed in two excellent papers by Michael McGraw, The Possibility of a Common McGrath Origin 9pp http://mcgrathsearch.com/files/Common_Origins_10-24-05b.PDF and The Origins of the McGrath family 272pp http://mcgrathsearch.com/files/Version01_A.pdf

McNamara (Mac Conmara)

The sept of MacNamara was, after the O'Briens, the most important and powerful of the Dalcassians of Thomond. They were hereditary marshals to the O'Briens and had the privilege of inaugurating their chief who was, of course, often a king. They descend from Cú Mara, grandson of Menma, d 1014, of the Ui Chaisséne, a branch of the Dál gCais.

There was frequent intermarriage between these two strong families. The sept was originally confined to a small territory, but by the end of the eleventh century they had become lords of Clancullen (which comprises a great part of East Clare) and they are so described by the Four Masters many times at various dates between 1099 and 1600. The sept in due course became two - the chief of West Clancullen (barony of Bunratty) being MacNamara Fyne (i.e. fionn, fair), and the chief of East Clancullen (baronies of Upper and Lower Tulla) MacNamara Reagh (i.e. riabhach, swarthy or grizzled). They earned a reputation as builders and are recorded as having built forty-two castles, fifteen fortresses and several friaries. Macmiccon MacNamara Fionn received a papal bull authorizing him to install Friars Minor in Quin Abbey, near Ennis, which he built in 1402. Many of the family lie buried in the shadow of the now roofless abbey. Like their ancient fortresses, the MacNamara seats are all in County Clare. From the woods around Cratloe Castle, built in 1610, came the oaks for London's old Westminster Hall and the royal palace in Amsterdam. Source:- http://www.araltas.com/features/mcnamara/


- (Greg Noonan)

Noonan surname is said by DeCourcy to be Eoganacht, but by others to be Dal gCais, while the name of their tuath lands, Muscraighe Ui Nunain (Tullylease, County Cork, and Broadford/Dromcolliher, County Limerick), seems to imply that they are descendents of Carbri Musc ("Muscraighe").The presumed progenitor of the name, Flaithbheartach hIonmhinen, "of the blood royal", was abbot of Inis Cathaig in the Shannon estuary and king of Munster in 915. However the Fianna warrior Cáel An Iarann Ua Nemhnainn of Tulach Lèis appears to have the same surname and hometown of the Noonans of Tullylease. Neither one seems to have a lineage traceable further back in time.

- (Jo Sturtevant)

In his 1876 Irish Pedigrees, or the Origin and Stem of the Irish Nation, John O’Hart recorded that “the ancestor of O’Noonan [branch] of Thomond and South Connaught [modern County Clare]” was Congall the second son of Aodh Caoimh, the first Christian king of all Munster (born c.570). Aodh Caoimh was crowned by St. Brendan the Navigator, who also consecrated the church of Tullylease. Aodh was a descendant of Cas Mac Connal (c.347-387) whose progeny are the Dál gCais.

Noonan/Nunan is the anglicized modern form of the well-attested Irish surname Ó Núanáin, which in turn appears to be descended through the Middle-Irish family name O’hIonmhaineáin from the Early-Irish Ua Nemhnainn, the cognomen of one of the three battalions of the 3rd-century Fianna Érieann.

The Irish government recognizes the surname Ó Núanáin as an ancient tuath name. Historically Noonans were the hereditary proprietors of Túatha Ua Nemhnain, a c.50-square-mile Gaelach tuath (clan kingdom) straddling the Cork-Limerick border east of Slieve Luachra. The kingdom’s seat was Castlelishen, ‘Oisín’s Castle’ (Oisín was the poet-warrior son of the famous Fianna leader Find mac Cumail) near Tulach Léis, Tullylease, the County Cork component of the kingdom and home of the Fianna hero Cáel Ua Nemhnainn.


There are a great many O Mahonys in Ireland - the name is included, usually without the prefix O, among the hundred commonest surnames. It belongs almost exclusively to West Munster. The vast majority of Mahony and O Mahony births are registered today in Co. Cork, the area historically associated with the sept. O Mahony chieftains were powerful, often described as princes. Their principal territory comprised the modern barony of Kinelmeaky and extended to the sea, with some fourteen castles on the coast of southwest Cork. The name O Mathghamhnain modernized spelling O Mathunais derived from Mathghamhain (Irish for bear), the grandson of Brian Boru, though his daughter Sabh, who m. Cian, who is No. 109 on the "O'Mahony" pedigree, by whom she had Mathgabhuin, the founder of the family of O'Mahony, in the county Cork. Mathghamhain was killed, with many more of the Desmond fighting men, at the Battle of Clontarf in 1014. (Edward MacLysaght, Irish Families and Diarmuid O Murchadha, Family Names of County Cork)


The O'Lynch family derives its origin from Aongus, the second son of Carthan Fionn Oge Mór, who is No. 93 on the O'Brien Kings of Thomond pedigree. They were lords of Owny-Tir, a territory on the border of the county of Tipperary, and they are mentioned as follows by O'Heerin:--
"The O'Lynches, estated chiefs,
Inhabit the wood in front of the foreigners,"

The settlement of the Galls or Foreigners, here alluded to, is the City of Limerick, which as early as the ninth century became the principal maritime station of the Danes; and the estate of the Lynches was, in all probability, the country lying around Castleconnell, in the barony of Owny and Ara, with a portion of the lands comprised in the county of the City of Limerick.