The original Irish from which the name derives is O Cathail, from the common personal name Cathal, sometimes anglicised ‘Charles’, which may in turn derive from the Old Irish catu-ualos, meaning ‘strong in battle’. Families of the name arose separately in different parts of Ireland, in Kerry, Galway, Tipperary and Clare. Originally the Galway family, located in the old diocese of Kilmacduagh near the Clare border, were most prominent, but their position was usurped by the O’Shaughnessys, and they declined. The southern families flourished, and the name is now most common in counties Cork, Kerry and Tipperary, while it is relatively infrequent in its other original homes.

Campbell is a Scottish surname, and one of the ten most numerous in that country, and one of the thirty most numerous in Ireland, with over two-thirds of those who bear the name living in Ulster and particulary common in counties Armagh, Down and Antrim. Originally a nickname, it comes from the Gaelic cam beul, meaning ‘crooked mouth’. Clan Campbell was founded by Gillespie O Duibhne, who lived in the thirteenth century, and was the first to assume the surname. His descendants included the most famous branch, the Campbells of Argyll, one of whose members was responsible for the massacre of MacDonalds of Glencoe to the famous feud between the two clans.
The vast majority of Irish Campbells are descended from the Scottish family, although in Co Tyrone the surname may be an anglicisation of the Irish Mac Cathmhaoil, from Cathmhaoil, meaning ‘battle-champion’.

One of the twenty five most common Irish surnames, Carroll comes, in the vast majority of cases, from the Irish O Cearbhaill, from Cearbhall, a very popular personal name thought to mean ‘fierce in battle’. It is widespread today throughout the three southern provinces of Connacht, Leinster and Munster, reflecting the fact that it arose almost simultaneously as a separate surname in at least six different parts of Ireland. The most famous of these were the Ely O’carrolls of Uibh Fhaili, including modern Co Offaly as well as parts of Tipperary, who derived their name from Cearball, King of Ely, one of the leaders of the victorious native Irish army at the battle of Clontarf in 1014. Although their power was much reduced over the centuries in the continuing conflict with the Norman Butlers, they held on to their distinctive Gaelic customs and way of life until the start of the seventeenth century.

Casy, O’Casey and MacCasey come from the Irish cathasach, meaning ‘vigilant in war’, a personal name which was quite common in early Ireland. This, no doubt, accounts for the fact that O Cathasaigh arose as a separate surname in at least five distinct areas, in counties Cork, Dublin, Fermanagh, Limerick and Mayo, with Mac Cathasaigh confined to the Louth/Monaghan area. In medieval times, the Dublin and Fermanagh Caseys were the most prominent, though their power had been broken by the seventeenth century; the name is still common in north Co Dublin to this day, as it is in Mayo and north Connacht generally. However, most present-day bearers of the surname are to be found in Munster, not only in Cork and Limerick. but also in Kerry and Tipperary.

In Irish O Caiside, ‘descendant of Caiside’, from Cas, meaning ‘curly-headed’, the surname is inextricably associated with Co Fermanagh, where the family were famous for centuries as poets, churchmen, scholars and hereditary physicians to the great Maguire chieftains. In Fermanagh, their original seat was at Ballycassidy, north of Enniskillen. As their healing skills became widey known, many Cassidys were employed by other chiefs, particularly in the north of the country, and the name is now particularly common in counties Donegal, Monaghan and Antrim, as well as in the original homeland of Fermanagh. Although less numerous elsewhere, the name is now also familiar throughout Ireland, with the smallest numbers to be found in Connacht.

The Irish version of the surname is Mac Fhlannchaidh, from the personal name Flannchadh, which, it is thought, meant ‘red warrior’. It originated separately in two different areas, in counties Clare and Leitrim. In the former, where they were a branch of the McNamaras, their eponymous ancestor being Flannchadh Mac Conmara, the Clancys formed part of the great Dal gCais tribal group, and acted as hereditary lawyers, or ‘brehons’, to the O’Brien chieftains. Their homeland was in the barony of Corcomroe in north Clare, and they remained prominent among the Gaelic aristocracy until the final collapse of that institution in the seventeenth century. The Leitrim family of the name were based in the Rosclogher area of the county, around Lough Melvin. Today, the surname is still most common in Leitrim and Clare, with significant numbers also found in the adjacent counties. The best known bearer of the name in modern times was probably Willie Clancy, a world-famous uilleann piper and folklorist from Co Clare, who died in 1973.

Clarke is one of the commonest surnames throughout England, Ireland and Scotland, and has the same remote origin in all cases, the Latin clericus, originally meaning ‘clergyman’ and later ‘clerk’ or ‘scholar’. In Irish this became cleireach, the root of the surname O Cleireigh, which was anglicised in two ways, phonetically as ‘Cleary’, and by translation as ‘Clerk’ or ‘Clarke’. Up to the beginning of this century, the two surnames were still regarded as interchangeable in some areas of the country. By far the largest number of Clarkes (with or without the final ‘e’) are to be found today in Ulster, a reflection of the great influx of Scottish settlers in the seventeenth century. Even in Ulster, however, without a clear pedigree it is not possible in individual cases to be sure if the origin of the name is English or Irish. Austin Clarke (1896-1974), poet, dramatist and novelist, was one of the most important Irish literary figures of the twentieth century.

O Cleirigh, meaning ‘grandson of the scribe’ is the Irish for both (O) Cle(a)ry and, in many cases in Ireland, Clarke, as outlined above. The surname is of great antiquity, deriving from Cleireach of Connacht, born c. 820. The first of his descendants to use his name as part of a fixed hereditary surname was Tigherneach Ua Cleirigh, lord of Aidhne in south Co Galway, whose death is recorded in the year 916. It seems likely that this is the oldest true surname recored anywhere in Europe. The power of the family in their original Co Galway homeland was broken by the thirteenth century, and they scattered throughot the island, with the most prominent branches settling in Derry and Donegal, where they became famous as poets; in Cavan, where many appear to have anglicised the name as ‘Clarke’, and in the Kilkenny/Waterford/Tipperary region.

Although Coleman is a common surname in England, where it is occupational, denoting a burner of charcoal, in Ireland the name is almost always of native Irish origin and generally comes from the personal name Colman, a version of the Latin Columba, meaning ‘dove’. Its popularity as a personal name was due to the two sixth-century Irish missionary saints of the name, in particular St Columban, who founded monasteries in many places throughout central Europe and whose name is the source of many similar European surnames: Kolman (Czech), Kalman (Hungarian), Columbano (Italian). The original homeland of the Irish O Colmain was in the barony of Tireragh in Co Sligo, and the surname is still quite common in this area. In the other region where the surname is now plentiful, Co Cork, it has a different origin, as an anglicisation of the Irish O Clumhain, which has also been commonly rendered as ‘Clifford’.

Collins is a very common English surname, derived from a diminutive of Nicholas. As with so many such names, in Ireland it may be either of genuinely English origin, or an anglicised version of an original Irish name. Two such Irish names were transformed into Collins: O Coileain, originating in Co Limerick, and O Cuilleain of West Cork. The O Coileain were forced to migrate from Limerick to the home territory of the O Cuilleain in the thirteenth century, so that it is now virtually impossible to distinguish between the two originals. The name is extremely numerous in Cork and Limerick, and indeed throughout the southern half of the country.

Conlon and its associated variants (O) Conlan and Connellan, are anglicised versions of a number of Irish names. O’Connallain, from a diminutive of the personal name Conall, ‘strong as a wolf’, originated in counties Galway and Roscommon. O Coinghiollain, whose derivation is unclear, arose in Co Sligo. The third of the Irish originals, O Caoindealbhain, comes from caoin, ‘fair’ or ‘comely’ and dealbh, meaning ‘form’, and is principally associated with the midlands and Co Meath. This last name was also anglicised ‘Quinlan’ or, in Munster, ‘Quinlivan’. The most common anglicisation, ‘Conlon’, is now distributed throughout Ireland, with particular concentrations in the original homelands of north Connacht and the midlands.

Again, a number of original Irish names have been anglicised as ‘Connolly’. The O Conghalaigh, from conghal, ‘as fierce as a wolf’, were based in Connacht, where the English version is now often spelt ‘Connelly’. The name arose as O Coingheallaigh in West Cork, while Ulster Connollys derive from both the O Conghalaigh of Fermanagh, who gave their name to Derrygonnelly, ‘Connollys oakwood’, and the Monaghan Connollys, for whom a number of separate origins are suggested, as a branch of the southern Ui Neill, or as a branch of the MacMahons. Whatever their origin, the Monagham family have been the most prominent of the Connollys, recorded as having ‘Chiefs of the Name’ up to the seventeenth century, and producing, among others, Speaker William Conolly (sic), reputedly the richest man in eighteenth-century Ireland, and James Connolly, labour leader, socialist writer, and signatory of the 1916 Proclamation of Independence.

In Ireland Conway may be of Welsh or Irish origin. In the former case it derives from the fortified town of Conwy, from the river of the same name, which term is thought to mean ‘reedy’. Descendants of settlers of the name are to be found in counties Kerry and Antrim, and elsewhere. The Irish origins of the name are manifold: it is the anglicised version of at least four separate names, including, in Co Sligo, O Conbhuidne, (‘yellowhound’), also anglicised ‘Conboy’; in Mayo O Conmhachain, sometimes also given as ‘Convey’; in Munster Mac Conmhaigh, from condmhach, meaning ‘head-smashing’, also anglicised ‘Conoo’, and in Derry/Tyrone Mac Conmidhe (‘Hound of Meath’), which has also been rendered as ‘MacConomy’, ‘Conomy’ etc. The surname is now numerous throughout Ireland, with perhaps the largest sinle concentration in Co Mayo.

The English version may derive from a number of Irish originals: O Corcrain, Mac Corcrain, O Corcain, and O Corcra, all stemming originally from corcair, meaning ‘purple’. The name has also been anglicised ‘Corkery’ and ‘Corkin’. It arose separately in different locations, in the O’Carroll territory encompassing parts of Offaly and Tipperary, and in Co Fermanagh. The name is now rare in Fermanagh, and it seems likely that the many Corcorans found in Mayo and Sligo are part of this group. Further south the name is also common now in Cork and Kerry as well as in Tipperary.

The origin of the surname Costello provides a perfect illustration of the way the native Irish absorbed the invading Normans. Soon after the invasion, the deAngulo family, also known as ‘Nangle’, settled in Connacht, where they rapidly became powerful. After only three generations, they had begub to give themselves a surname formed in the Irish manner, with the clan taking Jocelyn de Angulo as their eponymous forebear. Jocelyn was rendered Goisdealbh in Irish, and the surname adopted was Mac Goisdealbhaigh, later given the phonetic English equivalent ‘Costello’. Their power continued up to the seventeenth century, centred in east Mayo, where they gave their name to the barony of Costello. Today the surname is widely spread throughout Ireland, with the largest concentrations still in the historic homeland of Connacht.

Two original Irish versions of Coughlan (and its variants (O) Coghlan, Coglin and Cohalan) exist, O Cochlain and Mac Cochlain, both derived from cochall, meaning ‘cloak’ or ‘hood’. The Mac Cochlain were part of the great tribal grouping of the Dal gCais, claiming descent from the semi-mythical Cas, which also produced O’Briens and the McNamaras. Their territory was in the present Co Offaly, where they remained prominent up to the eighteenth century, Co Cork was the homeland of the O Cochlain, where the name has long been associated with the baronies of Est and West Carbury, and Barrymore. Interestingly, the surname tends to be pronounced differently in different areas of Co Cork, as ‘Cocklin’ in the west and ‘Cawlin’ in the east.

Craig is Scottish in origin, describing a person who lived near a steep or sheer rock, from the Scots Gaelic creag. It was very common near Edinburgh and the Lowlands in the fifteenth and sixteenth centuries, and was brought to Ulster by seventeenth-century Scottish settlers. In Ireland, it is still almost exclusive to Ulster, where it is now one of the most numerous surnames, being particularly frequent in Co Antrim, with large numbers also to be found in counties Derry and Tyrone. The most famous Irish bearer of the name, who organised the Ulster Volunteer Force against Home Rule after 1912, was prime minister of Northern Ireland from its creation in 1921 until his death in 1940. He was created Viscount Craigavon in 1927, and the new town of Craigavon in Co Armagh is names after him.

The surname in Irish is O Croinin, from a diminutive of cron, meaning ‘yellow’ or ‘swarthy’. A more accurate rendition of the original pronunciation would be ‘Croneen’, and this survives in placenames embodying the name Cooscronin (‘Cronins hollow) and Liccroneen (‘Cronins fort’) in west Cork, and Ballycroneen in Imokilly barony in east Cork. As the placenames imply, the origin of the family lies in Cork, in particular in the west of the county, where they were originally part of the Corca Laoighdhe. In the Gaelic genealogies of this tribal grouping, the Cronins are recorded as hereditary owners of territory to the west of present-day Clonakilty.

In form Crowley is English, a habitation name from an Old English term meaning ‘wood of the crows’, and no doubt some of those in Ireland bearing the name derive from English stock. However, the vast majority are of Gaelic extraction, with Crowley an anglicisation of O Cruadhlaoich, from cruadh and laoch, meaning ‘hardy’ and ‘warrior’. The Cruadhlaoch from whom the family take their name was in fact one of the Mac Dermots of Moylurg in Connacht, who lived in the mid-11th century. Some time later, probably in the thirteenth century, some members of the family migrated from Connacht to Co. Cork, and their descendants prospered and multiplied while the original western branch of the family declined. The vast majority of Irish Crowleys today are connected to the Cork branch, and that county is still home to most of them. Up to the seventeenth century they remained powerful, particularly in the Carbery region of the county, and acquired a reputation as formidable soldiers, literally living up to their name.

The surname Cullen may be Norman or Gaelic origin. The Norman name has been derived both from the city of Cologne in Germany, and from Colwyn in Wales. In Ireland this Norman family was prominent principally in Co. Wexford, where their seat was at Cullenstown castle in Bannow parish. Much more numerous in modern times, however, are descendants of the O Cuilinn, a name taken from cuileann, meaning ‘hollytree’. The name originated in southeast Leinster, and this area has remained their stronghold, with the majority to be found even today in counties Wicklow and Wexford. The most famous individual of the name was Paul Cullen (1803-78), Cardinal and Archbishop of Dublin, who presided over, and guided, the revival of the power of the Catholic Church in nineteenth century Ireland.

In form, Cunningham is originally Scottish, taken from the place of the same name near Kilmarnock in Ayrshire. This name was originally Cuinneagan, form the Scots Gaelic cuinneag, meaning ‘milkpail’, and was given its present form through the mistake of a twelfth-century English scribe, who transcribed the ending as ‘-ham’, a purely English suffix meaning ‘village’. Many Scottish Cunninghams came to Ireland in the seventeenth century Plantation of Ulster, and their descendants now form the bulk of those bearing the name in that province, where it is most numerous. As well as these, however, many of native Gaelic stock also adopted Cunningham as the anglicised version of their names. Among these ere the Mac Cuinneagain (Mac Cunnigan) of Co. Donegal, the O Cuinneagain or O Cuineachain (Kennigan/Kinahan) of Co. Antrim, the O Connachain (Conaghan) of counties Tyrone and Derry, the Mac Donnegain (Donegan) of Co. Down and the O Connagain (Conagan) of Co. Armagh. The most numerous, however, were the O Connagain and Mac Cuinneagain of Connacht, where the surname remains most common outside Ulster. The Scottish influx, together with the large number of Irish originals which Cunningham came to represent, have made it common and widespread throughout Ireland.

Curran, together with its many variants (O’) Curren, Corhen, Currane, Cureen etc. may come from the Irish O Corraidhin, or O Corrain, both deriving from corradh, meaning ‘spear’. The former version arose in Co. Donegal, where it still remains very numerous, while the latter was the name of several independent septs living in south Leinster/Waterford, Kerry, Galway and Leitrim. Today, the heaviest concentration of the name is found in Ulster, with the smallest number in Connacht, but the name is numerous and widespread throughout Ireland. Its most famous bearers were John Philpot Curran (1750-1817), the barrister and nationalist, and his daughter Sarah, who was secretly engaged to Robert Emmett. Thomas Moore’s song She is Far From the Land was inspired by her story.