Show ContentsCastellow History, Family Crest & Coats of Arms

The Castellow surname came to Ireland with the Anglo-Norman invasion of the 12th century. They were originally from the Norman family Nangles, or de Angulos, and descended in Ireland from Gilbert de Nangle. Costello and associated variations come from the personal name of a son of Gilbert, Oisdealbhach, whose name consists of the elements "os," which means "deer or fawn", and "dealbhadh," which means "in the form of" or "resembling." The Gaelic form of the surname Castellow, which predated the Anglicized version of the name, is Mac Oisdealbhaigh. This is the earliest recorded example of a Norman family assuming a Mac surname. The prefix O or Ó has sometimes been erroneously assumed. 1

Early Origins of the Castellow family

The surname Castellow 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 were granted lands by the Earl of Pembroke in the Anglo-Norman invasion of 1172.

Early History of the Castellow family

This web page shows only a small excerpt of our Castellow research. Another 138 words (10 lines of text) covering the years 1172, 1500, 1531, 1567, 1571, 1579, 1606, 1803 and 1865 are included under the topic Early Castellow History in all our PDF Extended History products and printed products wherever possible.

Castellow Spelling Variations

A single person's name was often spelt simply as it sounded by medieval scribes and church officials. An investigation into the specific origins the name Castellow has revealed that such a practice has resulted in many spelling variations over the years. A few of its variants include: Costello, MacCostello, Costillo, Costallo, Kostello, McCostello, Caustello, Costellow and many more.

Early Notables of the Castellow family

Notable amongst the family up to this time was Guillauame Costeley (1531-1606), Scottish organist and 'valet du chambre du roy' to Henry II and Charles IX of France. 2 Arthur Dudley Costello (1803-1865), was an English-born Irish novelist and travel writer.William Costeley was a Scottish musician, born 1531, settled in France, and was organist to Henri II and Charles IX. Author of a treatise called...
Another 65 words (5 lines of text) are included under the topic Early Castellow Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the Castellow family

Ireland experienced a dramatic decrease in its population during the 19th century. This was in a great measure, a response to England's imperialistic policies. Hunger and disease took the lives of many Irish people and many more chose to leave their homeland to escape the horrific conditions. North America with its promise of work, freedom, and land was an extremely popular destination for Irish families. For those families that survived the journey, all three of these things were often attained through much hard work and perseverance. Research into early immigration and passenger lists revealed many immigrants bearing the name Castellow: Honor Costello who landed in America in 1756; Bernard, Cornelius, Edward, Hugh, J.B. James, John, John B. Lawrence, Mark, Michael, Neal, Patrick, Peter, Philip, Thomas, Timothy, and William Costello, all landed in Philadelphia, Pennsylvania between 1833 and 1874.


Contemporary Notables of the name Castellow (post 1700) +

  • Bryant Thomas Castellow (1876-1962), American Democratic Party politician, Lawyer; U.S. Representative from Georgia 3rd District, 1932-37 3


The Castellow 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: Ne te quaesiveris extra
Motto Translation: Seek nothing beyond your sphere.


  1. MacLysaght, Edward, The Surnames of Ireland. Ireland: Irish Academic Press, sixth edition, 1985. Print. (ISBN 0-7165-2366-3)
  2. Smith, George (ed), Dictionary of National Biography. London: Smith, Elder & Co., 1885-1900. Print
  3. The Political Graveyard: Alphabetical Name Index. (Retrieved 2015, October 9) . Retrieved from http://politicalgraveyard.com/alpha/index.html


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