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

In its ancient Gaelic form, the Irish name O'Cassies was written Ó Cathasaigh, from the word "cathasach," which means watchful. 1

Early Origins of the O'Cassies family

The surname O'Cassies was first found in the counties of Fermanagh, Mayo, Dublin, Limerick, Cork and Roscommon. In early times, there were six unrelated septs of Ó Cathasaigh; the two most important were the erenagh (church steward) families of Devenish in the county of Fermanagh and the Lords of the Suaithni, in the present-day barony of Balrothery West, in County Dublin. The name has since become widely scattered. Although it remains common in County Dublin, it is now most prevalent in the southwest of Munster, with a smaller but still sizable population in north Connacht. This corresponds with the locations of the other four septs, which were found at Liscannon near Bruff in the County Limerick; near Mitchelstown in County Cork; in Clondara in County Roscommon; and in Tirawley in County Mayo, where two Casey septs were located. The Caseys of Mayo and Roscommon, like those in Fermanagh, were also notable as erenaghs.

Archaeological remains indicate that Caseys were also once found near Waterford. Furthermore, a sept of MacCasey was once located at Oriel and was common in County Monaghan. However, this sept is nearly extinct today. Due to the widespread dropping of Irish prefixes under British rule and their often-erroneous resumption in the 20th century, many MacCaseys are incorrectly thought to be O'Caseys.

Early History of the O'Cassies family

This web page shows only a small excerpt of our O'Cassies research. Another 113 words (8 lines of text) covering the years 1172, 1381, 1551, 1723, 1762, 1765, 1773, 1787, 1800, 1801, 1840, 1846, 1848, 1862 and 1870 are included under the topic Early O'Cassies History in all our PDF Extended History products and printed products wherever possible.

O'Cassies Spelling Variations

One name was often recorded under several different spellings during the life of its bearer because one must realize that attempting to record a Gaelic name in English is a daunting task at the best of times. Spelling variations revealed in the search for the origin of the O'Cassies family name include Casey, MacCasey, O'Casey and others.

Early Notables of the O'Cassies family

Notable amongst the family name at this time was William Casey, Anglican bishop in Ireland, nominated Bishop of Limerick by King Edward VI on 6 July 1551 and consecrated at Dublin on 25 October 1551. Thomas Casey JP (1765-1840) was an Irish politician and barrister who was a Member of Parliament for Kilmallock in the Irish House of Commons from 1800...
Another 59 words (4 lines of text) are included under the topic Early O'Cassies Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the O'Cassies family

The 18th and 19th centuries saw many Irish families immigrate to North America in search of land and opportunities. The largest influx of Irish immigrants to the United States and British North America came during the 1840s when the Great Potato Famine laid waste to their homeland. Hundreds of thousands left the island in an attempt to escape the starvation and disease it brought. Although the arrival of such a large number of destitute Irish was not welcomed by the established population in the United States and what would become known as Canada at the time, these Irish were an essential element to the rapid development of these growing industrial nations. They filled the demand for the cheap labor needed for the work in factories and in the construction of bridges, roads, canals, and railways. An examination of passenger and immigration lists has revealed many immigrants bearing the name of O'Cassies or one of its variants: Elizabeth Casey who arrived in Maryland in 1725; as well as Andrew, Cornelius, Daniel, David, Edward, James, John, Mary, Michael, Patrick, Richard, Thomas and William Casey, who all arrived in Philadelphia between 1840 and 1865..



The O'Cassies Motto +

The motto was originally a war cry or slogan. Mottoes first began to be shown with arms in the 14th and 15th centuries, but were not in general use until the 17th century. Thus the oldest coats of arms generally do not include a motto. Mottoes seldom form part of the grant of arms: Under most heraldic authorities, a motto is an optional component of the coat of arms, and can be added to or changed at will; many families have chosen not to display a motto.

Motto: Per varios casus
Motto Translation: By various fortunes.


  1. MacLysaght, Edward, Supplement to Irish Families. Baltimore: Genealogical Book Company, 1964. Print.


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