15 Irish language surnames

Caomhánach is an Irish language surname first assumed by Domhnall Caomhánach, eldest son of the 12th century Diarmait Mac Murchada, king of Leinster. A considerable number of anglicised variations of Caomhánach exist; some of the most common are Kavanagh, Cavanagh, Kavanaugh and Cavanaugh.

Piaras Feiritéar, or Pierce Ferriter, was an Irish poet.

Mac Amhlaoibh and Mac Amhalghaidh are two different Gaelic patronymic names with different origins and meanings, but which share the same or similar Anglicisations. These Gaelic names are borne by at least three unrelated native Irish clans or septs.

Mac Siúrtáin, aka Mac Jordan and Jordan, is the name of a Connacht family of Norman-Irish origins.

O'Cleary is the surname of a learned Gaelic Irish family. It is the oldest recorded surname in Europe — dating back to 916 CE — and is cognate with cleric and clerk. The O'Clearys are a sept of the Uí Fiachrach dynasty, who ruled the Kingdom of Connacht for nearly two millennia. As Connachta, the O'Cleary's ruled the kingdom of Uí Fiachrach Aidhne for nearly 800 years. They are the descendants of Fiachrae, son of the High King Eochaid Mugmedon, and elder brother of legendary High King Niall of the Nine Hostages. According to legend, they ultimately trace their ancestry back to the mythical Fir Bolg, as well as to Milesius, and consequently to Japheth, son of Noah.

Ó Coileáin is a Modern Irish surname generally belonging to the descendants of the last leading family of the Uí Chonaill Gabra, a sept and small but notable overkingdom of medieval and ancient Ireland, based in western County Limerick. Throughout much of their history the Uí Chonaill Gabra were in turn the leading sept of the greater regional overkingdom of the Uí Fidgenti, considered among the highest ranked princes or flatha in all the Province of Munster. Ó Coileáin/Ua Cuiléin is most commonly anglicized O'Collins and O'Cullane. The surname has also long been found in County Cork, believed largely due to the migration there, probably in the late 12th or early 13th century, of a junior branch of the County Limerick dynasty.

The O'Conor family are an Irish noble house and were one of the most influential and distinguished royal houses in Ireland. The O'Conor family held the throne of the Kingdom of Connacht up until 1475. Having ruled it on and off since 967, they ruled continuously from 1102 to 1475. Moreover, the O'Conor parent house the Uí Briúin and Síol Muireadaigh ruled Connacht on many occasions - but not continuously - between 482 and 956. The house of O'Conor also produced two High Kings of Ireland, Tairrdelbach Ua Conchobair and his son Ruaidrí Ua Conchobair, the last High King of Ireland. The family seat is Clonalis House outside Castlerea in County Roscommon.

Ó Conghalaigh is a Gaelic-Irish surname. It derives from the forename Conghal, meaning "fierce as a wolf". It is often anglicised as Conly, Conley, Conneely, Conneeley, Connolley, Connelley, Connalley, Connally, Connolly, Connelly, Connely or Ó Conghaile.

The Ó Dálaigh were a learned Irish bardic family who first came to prominence early in the 12th century, when Cú Connacht Ó Dálaigh was described as "The first Ollamh of poetry in all Ireland".

O'Fahey is the first anglicised form of Ó Fathaigh, an Irish noble family of County Galway who were historically the Chiefs of Poblewinterfahy. The patronym means "descendant of Fathaigh", whose name means "base" or "foundation". Cormac Ó Fathaigh is the first recorded bearer with the surname and was listed as a great-grandson of the eighth generation of Fathadh mac Aonghus, Fathadh Mac Aonghus is the purported ancestor of any Ó Fathaigh descendants. The surname largely became Fahey with many variations due to anglicization. The Ó Fathaigh are distinct from their Gael counterparts the Faherty and Flaherty. These names are sometimes confused and thought to be related but are all distinct unrelated surnames.

O'Farrell is the first anglicised form of Ó Fearghail, an Irish noble family of County Longford who were historically the Princes of Annaly. The patronym means "descendant of Fearghail", whose name means "man of valour". Fearghail fought alongside Brian Boru at the Battle of Clontarf and was a great-grandson of Angaile, or An Uillin, the 10th-century nobleman who conquered and gave his name to Annaly. The surname largely became Farrell. The O'Farrells are distinct from their neighbours the O'Farrellys.

O'Flaherty, is an Irish Gaelic clan based most prominently in what is today County Galway. The clan name originated in the 10th century as a derivative of its founder Flaithbheartach mac Eimhin. They descend in the paternal line from the Connachta's Uí Briúin Seóla. They were originally kings of Maigh Seóla and Muintir Murchada and as members of the Uí Briúin were kinsmen of the Ó Conchubhair and Mac Diarmada amongst others. After their king Cathal mac Tigernán lost out to Áed in Gai Bernaig in the 11th century, the family were pushed further west to Iar Connacht, a territory associated with Connemara today. They continued to rule this land until the 16th century.

Ó Maoilriain is an Irish Gaelic clan based in what is today County Tipperary and County Limerick. The clan claims descent from Cathair Mór of the Laighin, but they first appear in the historical record in the 15th century in the kingdom of Thomond. John O'Donovan claims they are distinct from the Ryan clan which ruled Uí Dróna in what is today County Carlow.

Ó Rothláin is an Irish surname. The name is a Patronym meaning "descendant of Rothlán." It is suggested that it is a possible variant of Ó Raghalláin, or Ó Roghallaigh. It is the pre-anglicised, Irish form of the names Rowlan, Rowland, Rowlands, Rollan, Rollin, Rolan and Rowley. The name can also be found spelled as Ó Rothlán, Ó Rothlain, O'Rothlain, Rothlán, and Rothlan.