Among the most illustrious Irish families of ancient origin is the McCloskey clan which had its earliest possessions in County Donegal, or Tirconnel, in Ulster, where the name is still numerous.
But the name is by no means confined to this section of Ireland, or indeed to Ireland itself, for it is a cognomen borne by descendants now widely distributed, and well represented in the United States.
Founder of the McCloskey family was Eogan, ancestor of the northern Hy Nials and son of Nial of the Nine Hostages, King of Ireland, A. D. 378. This is another of the families descended from Milesius through the line of his son Heremon. The ancient name of the family was like the present name -- Loskey -- which signifies "blind."
To this family goes the distinction of furnishing the first American cardinal, John McCloskey, who was the fourth bishop and the second archbishop of New York. He was born in Brooklyn, shortly after the arrival in America in 1808 of his parents, natives of Dungiven, County Derry, Ireland.
Cardinal McCloskey was one of the greatest prelates in the history of America. Three cathedrals were build by him, the Immaculate Conception in Albany, old St. Patrick's on Mott st., New York, now in the Chinatown section, which was rebuilt after the fire; and the present magnificent edifice at Fifth ave. and Fiftieth st.
Through his efforts the American College in Rome was saved from confiscation by the Italian government after he had enlisted the good offices of President Arthur and Secretary of State Frelinghuysen who appealed to the Italian authority through American minister Astor.
William George McCloskey, a native of New York city, was rector of the American College in Rome during the Civil War. He later became bishop of Louisville Ky. Another of this family was Rev. George McCloskey and still another Rev. Patrick McCloskey, pioneer priest in New York state.
This was in some newspaper, perhaps in the 1920s.
The McCloskey clan, although descended from the Milesian kings of Ireland, did not come into existence, in Ireland, until 1196 AD with the political murder of Murtough O'Loughlin, lord of Kinel-Owen, by Donagh, son of Bloscaidh (pronounced 'Blosky') O'Cahan, a subordinate chieftan. As was the custom after a noteworthy event, Donagh was permitted to begin his own family branch and adopted his father's first name as his family name and became Donagh O'Bloscaidh which, in time, evolved to McCloskey and other various spellings. It's beginning is well documented in the 'Annals of The Masters' and other historical records. It was a sub-set of the O'Cahans and ruled an area of what is now County Derry, centered on Dungiven. When the English 'Plantations' forced them off their arable land in the plains, they took refuge in the hilly, less fertile hillsides of Benedy Glen which runs to the south-east from Dungiven. From there they migrated to nearby counties or overseas.
The spelling of the name has varied over the years due to the past illiteracy of the population and it's officials. My experience in Ireland also showed me that, although my relatives spelt their name 'McCloskey' they pronounced it 'McCluskey'. Thus, spellings such as McLuskie, McCloskie, McClosey are all legitimate derivations.
Apparently, this form of the name McCluskey is the spelling used in the County of Antrim in Northern Ireland. It is also widely used in this form in the west of Scotland, especially Galloway. When it is spelled McCloskey, it is widely thought to belong to the area around Londonderry.
Bloskey O'Cahan slayed the heir to the throne of Ireland in 1196. His first name is the moniker that was assumed by this sept of the clan Kane.
The eponym of McCluskey is Glasgow, which is also a popular name in Eastern Northern Ireland.
McCluskey, in Scotland, is associated to the MacDonald Lord of the Isles clan. By geography alone it is possible to deduce where this association comes from.
The MacDonalds (spelled McDonnell) held large swathes of land in County Antrim in Northern Ireland.
Got this from: http://www.electricscotland.com/webclans/scotsirish/mccluskey.htm