O'Connor is an Irish surname from Ó Conchobhair, meaning “descendant of Conchobhar.” It is an old and widespread name, carried by several separate families in different provinces. Patrick Woulfe described at least six historical Ó Conchobhair families in Ireland, including the well-known Connacht dynasty.
For gifts that carry the name, browse the O'Connor Irish family gift collection. This article explores the surname's origins, regional histories and records.
What Does the O'Connor Surname Mean?
The Irish form is Ó Conchobhair, with Ó meaning “descendant of.” In Irish Names and Surnames, Patrick Woulfe explains Conchobhar as an old Irish personal name associated with “high will” or “desire.” Older and anglicized spellings include O'Conor, O'Connor, Connor and Connors, among others.
For an O'Connor family tree, follow records through the known county, parish and townland.
Which Ó Conchobhair families appear in Irish history?
Woulfe lists at least six historical families called Ó Conchobhair. They included the ruling family of Connacht; a separate Offaly family, seated at Dangan (later Philipstown); an O'Connor family in north Kerry, whose stronghold was Carrigafoyle; a Corcomroe family in west Clare; a Keenaght family in County Derry; and a family of Uí Breasail in the Oirghialla region.
The Connacht line became the most prominent in Irish political history. Its branches included Ó Conchobhair Donn, Ó Conchobhair Ruadh and Ó Conchobhair Sligeach. That prominence explains why Roscommon and the kings of Connacht feature so strongly in O'Connor history, alongside the name's other documented homelands in Offaly, Kerry, Clare and Ulster.
What Is the Connacht O'Connor Story?
The Connacht dynasty traced its surname to Conchobhar, a king of Connacht in the late tenth century. The family became one of the major ruling dynasties of medieval Ireland.
Ruaidrí Ua Conchobair is the best-known figure from this line. The Dictionary of Irish Biography records that he succeeded to the overkingship of Connacht in 1156 and claimed the high-kingship in 1166. His reign overlapped with the Anglo-Norman intervention in Ireland. In 1175 his representatives negotiated the Treaty of Windsor with Henry II, an agreement that briefly attempted to define the relationship between English-controlled territory and Ruaidrí's authority over other parts of Ireland. He abdicated the Connacht kingship in 1183 and died in 1198.
Ruaidrí's career is an important chapter in the history of the Connacht Ua Conchobair dynasty.
Where Were the Different O'Connor Families Found?
For the Connacht dynasty, County Roscommon is especially important, with wider connections across Connacht. Woulfe also records distinct historical O'Connor families in Offaly, Kerry, west Clare, County Derry and the Uí Breasail territory of Oirghialla.
That spread makes locality central to O'Connor research. County, parish, townland, religious denomination, occupation and the names of relatives are what separate one O'Connor family from another, and they point each family to its own regional history.
Is Connor the Same Surname as O'Connor?
Yes. Woulfe records Connor and Connors among the anglicized forms of Ó Conchobhair. Prefixes were dropped, restored and recorded inconsistently. When tracing Connor, Connors and O'Connor entries, compare places, relatives and dates alongside the spelling.
Many families dropped the O' in the eighteenth and nineteenth centuries, and some restored it later, so the same household can appear as Connor in one record and O'Connor in the next.
How Can You Research an O'Connor Family in Ireland?
Start with the most recent generation you can document and work backward. For Irish research, the National Archives of Ireland's 1901 and 1911 census returns can help place a household in a specific townland. IrishGenealogy.ie, the state's free record site, provides access to civil records and selected church records, while parish registers and local records can help bridge earlier generations.
Because O'Connor is widespread, begin with the family itself. First establish place, parents, spouses and neighboring relatives. Then compare that evidence with the historical geography of the relevant O'Connor family, from Roscommon and Sligo to Offaly, Kerry and Clare.
O'Connor Migration and the Diaspora
O'Connor families appear throughout the Irish diaspora in Britain, the United States, Canada, Australia and elsewhere. Nineteenth-century migration, including the upheaval of the Great Famine period, carried many Irish families abroad. For descendants researching an emigrant O'Connor, records at the destination can be just as important as Irish records because naturalization files, death certificates, church records and obituaries often preserve a county or parish of origin.
Frequently Asked Questions About O'Connor
Is O'Connor an Irish surname?
Yes. O'Connor is an anglicized form of Irish Ó Conchobhair, “descendant of Conchobhar.”
Which parts of Ireland are O'Connor families from?
The best-known line ruled Connacht from Roscommon. Patrick Woulfe also records Ó Conchobhair families in Offaly, north Kerry, the Corcomroe district of west Clare, Keenaght in County Derry and Uí Breasail in Oirghialla.
Where should I start researching an O'Connor ancestor?
Start with a known person and a known place. Use census, civil and church records to establish county, parish or townland, then match the family to the historical O'Connor line of that region.
Sources and Further Research
- Patrick Woulfe, Irish Names and Surnames (1923), entry for Ó Conchobhair.
- Dictionary of Irish Biography, Royal Irish Academy, “Ua Conchobair, Ruaidrí.”
- National Archives of Ireland — Census Search.
- IrishGenealogy.ie — the state's free civil and church record resources.
- National Library of Ireland — Office of the Chief Herald.