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BRENNAN Family History

Ó Braonáin - anglicised Brennan, earlier O Brenane et al. a diminutive of Braon, of uncertain meaning.

Mac Branáin - anglicised Brannan, Brennan, earlier M'Brenan etc. the root probably being a diminutive of 'Bran', probably for 'raven'.Ó Branáin- this name added by Woulfe in 'Sloinnte Gaedheal is Gall' (1923). From 'Bran' or 'raven'.

Of the first name there were several families throughout Ireland: of Ossory in northern Co Kilkenny, where they were chiefs of Uí Duach, and a numerous name there; of Crevagh in Co Westmeath, also numerous there; a family in the south east of Co Galway, influential and numerous at the end of the 16th century; Uí Bhraonáin of Dunkerron in Co Kerry.

Of the second surname we look to Co Roscommon to find the Mac Branáin family that anciently held considerable power in Corca Achlann. Legend has it that they were of druidic descent, but were friendly to the evangelising St Patrick! This name, like the two others, has long been generally anglicised as Brennan.

Woulfe (op. cit.) writes that Uí Bhranáin were ecclesiastics in Derry and Co Fermanagh. There may have been some confusion with the distinct surname Brannagan (Ó Branagáin).

From these disparate sources we would expect the surname Brennan to be widespread over Ireland.

Looking in the 1659 'Census' of William Petty, Cromwellian bureaucrat, we find under the appelation of 'Principal Irish Name' in that document:

(Ó Braonáin)
Co Kilkenny
46 families of Brenan in the barony of Gowran; barony of Ida etc.; Knocktopher, Brenan 06; Skillelogher, Brenon 09; Crannagh Brenon 08.

Co Westmeath
Corkerie barony, Branan & Brenan 05; Fertullagh, Brynan 05, Brenan 02; Moycashel, Brenan 05, Brynan 05.

Co Kerry
Barony of Trughanac, O Brenane 11; there are none listed in the Dunkerran Barony in the 'Census'.

Co Laois
Ossory Barony, Brenan 06; Upper Ossory, Brenan 10; Cullenagh, Brenan 10; Maryborough, Brenan 10; Sliemargagh, Brenan 28; Ballyadams, Brenan 7; Stradbally, Brenan 9.

I could find no trace of Ó Braonáin in the lists for Derry or Fermanagh.

Co Monaghan
O Brynan, 09.

(Mac Branáin)
Co Roscommon
Barony ibid. and Athlone borough, Brenan 7 Branan 07; Boyle Barony, O Brenan & Brennan 30; Athlone Barony, Brenan 9.

By the time of the mid 19th century Griffith's 'Valuation' of households, the most numerous Brennan households were in the following counties: Kilkenny 648, Laois 365, Sligo 271, Roscommon 255, Mayo 233 and Wexford 148.

The 1890 births distribution of Brennan is: Leinster 178, Connacht 94, Munster 50 and Ulster 36.

The arms opposite are self explanatory as to which family they apply. The Irish Times Ancestor website chooses and illustrates the following arms for Brennan: 'Gules, two lions rampant, combatant, supporting a garb all or, in chief three swords, two in saltire points upwards, and one in fess point to the dexter, pommels and hilts of the second: Crest: an arm in armour, grasping a sword, all proper'.

Two famous Brennans

John Brennan (1625-1693) Archbishop of Cashel in this tubulent period.

Abbé Pierre O Brenan, executed by revolutionaries in France in 1794.

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Tell us about any famous BRENNAN (or surname variant) you think we should add here. We will get our genealogists to check them out and add them to the list. Thanks!


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Michael Brennon…Roscommon - 1768. Married to Mary (Marion) Campbell.

Rosie Brennan

Hello all. My father was a John Brennan b1907 in Dunmore, Co Kilkenny. I have been doing my family tree on and off for many years, always hitting brick walls due to the amount of Brennans in that area. My great uncle Martin is a mystery. He’s in the 1901/1911 census but after 1911 no trace of him at all. He was born 18/11/1879 - address given as Mothil parish of Muckalee, Co Kilkenny... Any connections out there... if so I would love to hear from you.

Maureen (Brennan) Mross

looking for info on James and Ann Brennan. Born 1830's? May have been son Thomas, his son Thomas, my dad Richard, and me, Maureen. Ancestry says Lienster or Roscommon as ancestral places. Would appreciate any info! Thanks!

Anne Brennan

Any Brennan with a relative from Waterford, Ireland, living there in the early - mid 1900s?

Anne Brennan

My name is Ann Brennan my father was Harry brennan from maghera his father was Edward that's all I know any help would be grateful.


Hello everyone, I and my two brothers live in Plymouth in Devon England and our parents are both deceased, when they were alive my grandparants were farmenrs and lived in the Hoath area in what is now Northern Dublin, we are all over 60, there are lots of relatives scattered around Dublin. My mothers name was Elizabeth Byrne and we have contact with some of her brothers and sisters.

richard brennan

From whence came Sad beneath the shield?


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