This is one of the most frequent surnames in
Ireland. It derives from the two Irish originals O'Braonain and Mac Branain . The Mac Brandin
were chiefs of a large territory in the east of the present Co.Roscommon and the majority of the
Brennans of north Connacht, counties Mayo, Sligo and Roscommon descend from them.
O'Braonain originated in at least four distinct areas: Kilkenny,
East Galway, Westmeath and Kerry. Of these the most powerful were the O'Braonain of
Kilkenny, chiefs of Idough in the north of the country. After they lost their land to the English, many of them
became notorious as leaders of the outlaw bands. A separate family,
the O'Branain, are the ancestors of many Brennans of counties Fermanagh
and Monaghan where the name was also anglicised as Brannan and Branny.|
Brennan Clan came into existence over a thousand years ago when
Braonan, the son of Cearbhall, Viking King of Dublin, settled in the
area of north Kilkenny, then known as Idough. Until the coming of
the Normans in the 12th century the Brennans were the most powerful
clan in the area, having defeated all local opposition.
the 17th century the Brennan lands were granted to Christopher
Wandesforde and the Brennans lost all legal rights to their land.
then Brennans have left Ireland and settled every corner of the
world. In 1990 the first Clan Gathering was in
Castlecomer where hundreds of the descendants of those
Brennans came back to the land their forefathers.