Summary of Surnames prefixed Mac and O

Robert E. Matheson
Chapter IV | Start of chapter

By comparing the foregoing Lists with the Table at the end of this Report, it can be seen how far these families are at present represented in the localities formerly inhabited by them and in the country at large. The above Tables, however, exhibit the information for counties proper, whereas the Tables on pages 32-34 and 37-75 are compiled by Registration Counties, i.e., groups of entire Poor Law Unions most nearly representing the area of the county proper. The differences are for the most part slight, but in a few instances the name may be found in the county proper immediately adjoining.

It will be seen that some of these names have spread all over Ireland, such as Murphy, Kelly, Kennedy, Maguire, Quinn, &c. Some of these Families have disappeared, or have migrated to another part of the country, or their names have become so altered in process of time as to be incapable of identification.

In many cases, however, the descendants of the ancient families are still domiciled in the same tracts as their forefathers, as shown in the following instances:—

The MacCabes were a warlike clan originally from County Monaghan, but subsequently settled in County Cavan. At the present time they are largely represented in the population of each of these counties.

The MacCarthys were anciently Kings and Princes of Desmond, Southern Munster, i.e., County Cork, the greater part of Kerry, and portions of Waterford and Tipperary. The MacCarthys are now resident principally in the Counties of Cork, Kerry, and Limerick, more than half of them being found in County Cork.

The MacDermotts were ancient Princes of Moylurg, having their territories in the Barony of Boyle, County Roscommon, and parts of the Parishes of Islandeady, Turlough, and Breaffy, in Counties Sligo and Mayo. Their chief fortress was on an island in Lough Key, near Boyle, and they were hereditary Marshals of Connaught. At the present time Connaught is the province in which the MacDermotts are principally found, and half of the persons of the name in that province belong to County Roscommon.

The Munster MacMahons formerly possessed the greater part of the Baronies of Moyarta and Clonderalaw, in the County Clare, in which county the predominant name now is McMahon.

The O’Byrnes anciently possessed the greater part of the Barony of Ballinacor, County Wicklow, and were powerful Chiefs in that part of the country. Byrne is the leading name now in the Counties of Wicklow, Dublin, and Louth.

The original habitat of the O’Driscolls was the Barony of West Carbery, in County Cork, where O’Driscoll was Lord of Baltimore, and possessed the Island of Cape Clear and adjacent territory. The great majority of the present Driscolls are to be found there.

The O’Doghertys were a powerful Sept in County Donegal, and were located in Inishowen Barony, of which O’Dogherty was Lord. The Doghertys or Dohertys are numerously represented there at the present time.

The O’Flahertys were originally located in the Barony of Clare, County Galway, but in the thirteenth century, having been expelled from this territory, they settled in the Barony of Moycullen, and were styled Lords of Iar Conacht or West Connaught. A large number of the Flahertys are now to be found in the Baronies of Moycullen, Ross, and Ballinahinch, in County Galway.

The O’Gallaghers were a warlike Clan in the Baronies of Raphoe and Tirhugh, County Donegal. As will be seen from the Table on page 33, Gallagher is now the most numerously represented name in County Donegal.

In ancient times the O’Keeffes were Marshals and chief military leaders of Desmond. They possessed several castles, and were styled Princes of Fermoy. The principal county for the Keeffes and O’Keeffes at present is Cork.

The O’Mahonys were anciently located in Cork and Kerry, where they were powerful Chiefs and sometimes styled Princes. They had several castles along the sea-coast. In County Cork an O’Mahony was Lord of Ivaugh, in the Barony of West Carbery, and an O’Mahony was Chief in Kinalea Barony. In County Kerry there was a Chief of the name in the Barony of Iveragh, and there were O’Mahonys in the Barony of Clanmaurice. The majority of persons of the name of Mahony or O’Mahony are still found in these two counties.

The O’Malleys were celebrated Chiefs whose territory comprised the present Baronies of Murrisk and Burrishoole in the County Mayo. The Malleys and O’Malleys are now located principally in the two baronies named, and in that of Erris, in County Mayo.

The O’Meaghers were formerly powerful Chiefs possessing the Barony of Ikerrin, in County Tipperary, of which O’Meagher was Lord. The Meaghers or Mahers are principally found in the County Tipperary at present.

The O’Mearas had an extensive territory in the Barony of Upper Ormond, County Tipperary, in which O’Meara was a Chief. The name of their principal residence, Tuam-ui-Meara, is still retained in the town of Toomyvara. The Mearas or O’Mearas are still numerous in that locality.

The name Moriarty is now largely represented in County Kerry, in which county the O’Moriartys were Chiefs in the Barony of Dunkerron.

O’Mulvey was a Chief in the Barony of Mohill, County Leitrim, in which county about 50 per cent. of persons bearing the name Mulvey are now found.

The name Noonan occurs chiefly in Cork, in which county the O’Noonans formerly dwelt. O’Noonan was a Chief in Duhallow Barony, and there were O’Noonans in Barrymore and Kinalea Baronies.

There were two branches of the O’Ryans or O’Mulrians—the Carlow branch, in which county O’Ryan was Prince of Idrone— and the Tipperary branch, in which county one O’Ryan was Lord of Owney and Arra, and another Chief of Borrisoleigh. They also had possessions in County Limerick. The Ryans are now found in the Counties of Carlow, Kilkenny, Limerick, and Tipperary, the last county having by far the largest number. The Ryans of Tipperary are in some places so numerous that they also distinguished in the records by additional names appended to the surnames, such as—Ryan (Bawn); Ryan (Buckly); Ryan (Cooper); Ryan (Cormack); Ryan (Corney); Ryan (Dalton); Ryan (Dan); Ryan (Jack); Ryan (James); Ryan (Larry); Ryan (Ned): Ryan (Owen); Ryan (Russell); Ryan (Tim Daniel).

There were several branches of the O’Sullivan family; one was located in County Cork, where they were Princes of Beara, now Bere and Bantry Baronies, and were called O’Sullivan (Beara). Another (O’Sullivan Mor), occupied portion of County Kerry, where they were Lords of Dunkerron. At the present time the Sullivans and O’Sullivans are most numerous in the Counties of Cork and Kerry.

The O’Tooles were celebrated Princes of Imaile, in County Wicklow, and had their seat in the Glen of Imaile, which still retains that name. Their power extended into County Kildare. A considerable number of Tooles are still resident in the County Wicklow.