Murphy: O Murchadha (for derivation see Morchoe). Murphy is the most numerous name in Ireland and is that of three different steps as indicated on the Map. The resumption of the prefixes O and Mac, which is the modern tendency with most Gaelic-Irish names, has not taken place in the case of Murphy.
Kelly: O Ceallaigh. (The derivation of Kelly is uncertain; the most probable suggestion is that it is from ciliate, strife). The most important and numerous step of this name is that of the UI Maine. There are several other steps as indicated in Map. Kelly is the second most numerous name in Ireland. In 1890 less than 1% of them had the prefix O but this has since been to some extent resumed.
O'Sullivan: O' Suileabhain (while there is no doubt that the basic word is suil (eye) there is a disagreement as to the meaning of the last part of the name). This is the most numerous surname in Munster and is the third in all Ireland. Originally of south Tipperary, the O'Sullivans were forced westwards by the Anglo-Norman invasion where they became the leading steps of Munster.
Walsh: Breat (h) nach (Walshman) which is re-anglicized also as Brannagh, Brannick etc, A name given independently to many unconnected families in different parts of the country and now the fourth most numerous of all Irish surnames. It is sometimes spelt Welsh, which is the pronunciation of Walsh in Munster and Connaucht.
Smith: When not the name of an English settler family, Smith is usually a synonym of MacGowan, nearly always so in Co. Cavan.
O'Brien: O Briain. A Dalcassian sept, deriving its name and historical importance from the family of King Brian Boru. Now very numerous in other provinces as well as Munster, being the fifth most numerous name in Ireland. In some cases O'Brien has been made a synonym of O'Byrne and in others of the Norman Bryan.
Byrne:O Broin (bran, raven). A formost sept in east Leinster, prominent in Irish history, especially in the resistance to English conquest. Byrne is now of the most numerous names in Ireland.
Ryan: O Maoilriain is the correct form in the homeland of the great sept of Ryan, formerly Mulryan; but it is now usually abbreviated ti O Rain, Which is properly the name of a small Leicester Sept. Ryan is the most numerous name in Co, Tipperary having almost four times the population of the next order (O'Brien and Maher).
O Connor: O Conchobhair. The name of six distinct and important septs. In Connacht there were O'Connor or O'Conor Don (of which was the last high king of Ireland) with its branches O'Connor Roe and O'Conor Sligo; also O' Connor Flay (ie of Offaly), O'Connor Kerry O'Connor of Corcomroe (north Clare). The prefix O, formerly widely discarded, has been generally resumed.
O'Neill: In addition to the famous O'Neills of Ulster there were septs of the name in thomond (see Nihil), Decies(Co. Waterford) and Carlow. The main family of O'Neills, dominant in Tyrone up to the collapse of the Gaelic system in the seventeenth century, descend from the famous Niall of the Nine Hostages. A branch Knowan as Clandeboy (clann Aoidh Bhuidhe) setteled in Co, Antrim in the fourteenth century. The name is numerous throughout Ireland especially in Tyrone and Antrim.
O Reilly: O Raghailligh. One of the most numerous names in Ireland,especailly in Co. Cavan. The prefix O has been widely resumed in the anglicized form. The head of this important sept was chief of Bernie O' Reilly. Map Cavan-Meath.
Doyle: O Dubhghaill. This is ths most numerous names in Leinster. The main sept is of Norse origin,well established before the Anglo-Norman invasion.Map Wexford
McCarthy: Mac Carthaigh (carthach, loving). The chief of the Eoghanacht and one of the leading septs of Munster, prominant int the history of Ireland from the earliest times to the present. MacCarthy is the most numerous Man name in Ireland. Map Cork , Kerry
Gallagher: O Gallchobhair. This name (gallchobhar, foreign help) has at least 23 variant spellings in anglicized forms, several of them beggining with Goole instead of Gal. It is one of the principal septs in Co. Donegal. Map Donegal.
O'Doherty: O Dochartaigh (dochartach, hurtful). The leading sept of Inishtown Doherty is now one of the most numerous names in Ireland, it is still mainly found in Ulster. Map Donegal
Kennedy: O Cinneide (ceann, head-eidigh, ugly). An important Dalcassian sept of east Clare which settled in north Tipperary and spread as far south as Wexford whence came from the family of John.F.Kennedy. Map Tipperary
Lynch: This is a dual origin. The Norman de lench is more numerous and important, being predominant among the "Tribes of Galway". The Gaelic O Loingsigh (loingseach, mariner) giving Lynch and Linchy the name of several distanct septs. MapAntrim -Down, Cavan, Clare, Cork and Tipperary.
Murray: Apart from Scottish Murrays have O Muireadhaigh formerly O Murry of Ui Maine; Mac Giolla Mhuire (MacElmurray or Gilmore); and Mac Muireadhaigh (MacMurray) very numerous in Co. Donegal. Map Down and Roscommon.
Quinn: The most numerous surname in Tyrone and very numerous in all the provinces ,it is that of four distinct steps as in Map. Properly Quinn in Irish is O Cuinn, from the personal name Conn; but in Ulster it is often O Coinne, more correctly anglicized Quinney.Map Antrim, Clare, Longford and Tyrone.
Moore: A well known English name much substituted for the Irish O More. It is widespread throughout Ireland, but really numerous only in Co, Antrim and Dublin.
McLaughlin: Mac Lochlainn (from a Norse personal name). Of Inishtown; a senior branch of the northern Ui Neill. They lost their early importance as a leading sept of Tirconnell in the thieteenth century, but are still very numerous in their original homeland Cos Donegal and Derry-were usually thier name is spelt MacLaughlin; MacLaughlin, also numerous, is more widespread. Minor septs in Connacht were akin to the MacDermots and the O' Conners. Map Donegal.
O'Carroll: O Cearbhaill. Several different septs were so called: those of Ely O'Carroll and Oriel are important; minor septs were in Kerry and Leitrim. Map Kilkenny, Louth andOffaly.
Connolly: O Conghaile (Connacht and Monaghan), O Coingheallaigh (Munster). Spelt Connelly in Co Galway where the family is of the Ui Maine. The name is widely distributed over all the provinces. James Connolly was of a Co Monaghan family. Map Galway, Fermanagh, Meath, and Monaghan.
Daly: O Dalaigh (dalach, from dail, assembly). One of the greatest names in Irish litraturen Originally Westmeath, but subsets in several different localities as Map. as that in Desmond appears in the records as early as 1165 it is probable that this was a distinct sept. Map Cllare, Cork, Galway and Westmeath.
O'Connell: O Conaill. One of the most important Kerry septs. Daniel O'Connell was one of the leading families of Derrynane. Map Kerry.
Wilson: This is by far the most numerous English surname in Ireland; it is mainly found in Ulster.
Dunne: O Duinn or O Doinn. Usually spelt with a final E. One of the numerous names in the midland counties. Formely called O'Doyne (Lords of Iregan).
Brennan: O Braonain. The name of four unrelated septs, located in east Galway, Kerry and westmeath. The Co, Fremanagh sept of O Branain was also anglicized Brennan as well as Brannan Map Kerry and Killkenny.
Burke: de Burca. This is one of the most important and most numerous Hiberno-Norman names. First identifed with Connacht it is now in all the provinces (least in Ulster). Many subsepts of it were fotmed called machugo, MacGibbon, Mac Seoinin and MacRedmond. Map Galway, Mayo and Tipperary.
Collins: Though this is a well-known English name in Ireland it is nearly always the anglicized form of O Coileain, which is also, Cullane. This sept of Co. Limerick. Another someties spelt O Cuileain is of Corca Laoidhe. In west Ulster Collins ia Mac Coileain. Map cork and Limerick.
Campbell: Mac Cathmhaoil. An Irish sept in Tyrone; in Donegal it is usually of Scottish gallaglass origin, viz. Mac Ailin a branch of the clann Campbell (whose name is from Campbell, crooked mouth). Many Campbell's are more recent Scottish immigrants. The name has been abbreviated to Camp and even Kemp in Co, Cavan.
Clarke: An English name which usually stands for O'Cleary in Ireland
Johns(t)on: Many of the Johnsons in Ireland , especially in Ulster, are of Scottish origin. This name in Ireland , however, is often a translation of MacShane and so aa branch of the O'Neills. It is much less numerous than Johnston, which is a British toponymic, but is also used synonymously with Johnston.
Hughes: well-known English name very numerous names in all the provinces except Munster. It is often also a synonym of O hAodha.
O'Farrell: O Fearghail (man of valour). A numerous name and important sept of Annaly whose chief's seat was Longford, formerly called Longphort Ui Fhearghail (i.e. O'Farrell's fortress). The name is now widespread throughout all provinces. Map Longford.
Fitzgerald: Mac Gerailt. One of The two greatest families which came to Ireland as a result of the Anglo-Norman invasion. It had two main divisions, Desmond (of whom are the holders of the ancient titles Knight of Kerry and Knight of Glin); and Kildare, whose leaders held almost regal sway up to the time of the Rebellion of Silken Thomas and the execution by Henry V111 of Thomas and his near relatives in 1537. The name is very numerous. Map Cork, Kerry, Kildare, and Limerick.
Brown: One of the tribes of Galway. Other important families of Brownes were established in Ireland from the Anglo-Norman invasion onwards. The Brownes of Killarney, who came in th esixteenth century, intermarried with the leading families and were notable for their survival as extensive Catholic landowners throughout the period of the Penal Laws. Yet another important family of the name was of the Neale, Co. Mayo. In that county Browne has also been used as a synonym of (O) Bruen. Map Galway and Limerick.
Martin/MacGillmartin: This is one of the most numerous surnames in Ireland, as it is also in England and Scotland. One family of Martins are included in the fourteen 'Tribes of Galway', having come to Ireland at the time of the Anglo-Norman invasion. The name is also used as an abbreviation of Gillmartin. In Tyrone Martin, foremly Mac-Martin is the name branch of the O' Neills. O'Martin was established name in Westmeath in the sixteenth century.
Maguire: Mag Uidhir (odhar, gen, and uidhir, dun-coloured). the leading sept of Fermanagh. Many of tidies sept have been distinguished in in the history of Ireland. Map Fermanagh.
Nolan/Knowlan: O Nuallain (nuall, shout). In early times holding hereditary office under the Kings of Leinster, the cheif of this sept was known as Prince of Foherta, i.e. the barony of forth, in the present county of Carlow where the name was and still is very numerous. A branch migrated to east Connacht and Co. Longford. In Roscommon and Mayo Nolan is used synonymously with Holohan (from the genitive plural); and in Fermanagh as an anglicized from of O hUltachain. There was also a sept of the name of Corca Laoidhe, which is now represented in Co. Kerry. Map Carlow.