Sources for Mac and O in Surnames

Irish surnames are fascinating, complex, confusing and have irritated many for a variety of different reasons.  The disappearance of the Mac and O and reappearance over centuries frequently exasperates the searcher of Irish roots whether amateur or professional. Which is more common? Why do some families use the Mac and others not? Some of these issues can be solved by knowing a little of Irish historical events.

This shows investigates the impact of the Tudor conquest and the  subsequent perception of the barbarous nature of Irish surnames using Mac and O. It evaluates the need for names to sound English and ‘civilized’, no longer belonging to a barbarous sounding tongue. The use of the Mac and O and sources for same can be found by listening to ‘The History of the Mac and O in Surnames”



Edward MacLysaght, The Surnames of Ireland (Dublin, 1999). – A detailed and compact guide giving a wealth of information of the background of Irish family names. More than 4,000 Gaelic, Norman and Anglo-Irish surnames.

John Grenham   This is excellent value and provides an expert research tool for those mapping surnames from Griffiths valuation.

UCC Corpus of Electronic Text:

Facebook page Irish Medieval History source to

Irish Genealogy, Heraldry and family history at the National library of Ireland
PDF sources here

An excellent annotated bibliographic recordfor Irish surnames can be seen by the following bibliography at

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