Show ContentsO'Kileen History, Family Crest & Coats of Arms

The Irish surname O'Kileen originally appeared in Gaelic as Ó Cillin. 1

Early Origins of the O'Kileen family

The surname O'Kileen was first found in County Mayo (Irish: Maigh Eo) located on the West coast of the Republic of Ireland in the province of Connacht, where they held territories was at Ballykilleen since early times. This lofty family were the ancient Chiefs of Fingal, Earls of Fingal and Lords Killeen.

Saint Kilian, (also spelled Killian) from the Irish: Cillian, (c. 640-689) was an Irish missionary bishop and the apostle of Franconia. He was born in Mullagh, County Cavan, and is the patron saint of the parish of Tuosist, in County Kerry. Saint Kilian's feast day is July 8th and St. Kilian's Abbey, at Würzburg is named after him.

Today there are two Killeen Castles in Ireland: one located at Dunsany, in County Meath, that dates back to about 1180, but today's structure is a restoration of the 19th century after a fire in 1981. It will include a luxury golf course designed by Jack Nicklaus. The second Killeen Castle is a 17th century castle at Killeen, in Castlegar, County Galway.

There are some scanty records of the family in Scotland, but they are rather late: "John Killan in Cleckaime, parish of Lesmahago, 1677, and Robert Killand in Deidwatters, parish of Lesmahago, 1678. This name in Irish is O'Cilleain, descendant of Cillean, a diminutive of Ceallach, an ancient and once very common name." 2

Early History of the O'Kileen family

This web page shows only a small excerpt of our O'Kileen research. Another 122 words (9 lines of text) covering the years 1172, 1180 and 1981 are included under the topic Early O'Kileen History in all our PDF Extended History products and printed products wherever possible.

O'Kileen Spelling Variations

Irish names recorded during the Middle Ages are characterized by many spelling variations. This preponderance of variations for common names can be explained by the fact that the scribes and church officials that kept records during that period individually decided how to capture one's name. These recorders primarily based their decisions on how the name was pronounced or what it meant. Research into the name O'Kileen revealed many variations, including Killeen, Killen, Killion, Killian, Killin, Gilin, Killan, Killoon, O'Killen, McKillen and many more.

Early Notables of the O'Kileen family

More information is included under the topic Early O'Kileen Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the O'Kileen family

Irish immigrants began to leave the English-controlled Ireland in sizable numbers during the late 18th century. Many of these Irish immigrated to British North America or the United States in the hopes of gaining their own tract of farmland. This pattern of migration grew steadily until the 1840s when the Great Potato Famine caused a great exodus of immigrants to North America. These immigrants differed from their predecessors in that they were desperately fleeing the disease and starvation that plagued their homeland, and many were entirely destitute when they arrived in North America. Although these penniless immigrants were not warmly welcomed when they arrived, they were critical to the rapid development of the United States and what would become known as Canada. Many went to populate the western frontiers and others provided the cheap labor the new manufacturing sector and the building of bridges, roads, railways, and canals required. A thorough examination of immigration and passenger lists has revealed some of the earliest people to arrive in North America with name O'Kileen or one of its variants: Jenkins Killen, who settled in Virginia in 1805; Alexander, Denis, James, John, Patrick, and Robert Killen, who all arrived in Philadelphia between 1840 and 1860.



  1. MacLysaght, Edward, The Surnames of Ireland. Ireland: Irish Academic Press, sixth edition, 1985. Print. (ISBN 0-7165-2366-3)
  2. Black, George F., The Surnames of Scotland Their Origin, Meaning and History. New York: New York Public Library, 1946. Print. (ISBN 0-87104-172-3)


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