Breen
 
"The 'Breen' family" ... "name may come originally from O'Breen or Mac Breen. MacBreen was anciently centered in the barony of Knocktopher, in Co. Kilkenny, within the more ancient territory of Ossory. In the wake of the 12th century Norman invasions the power of this family was broken by the Walsh family, hence they settled in Wexford, where the name was most popular a century ago.
 Keatings History gives the family thusly: 'Mac Breen, of the land of the fortress, Rules over the clans whom I remember'. O'Hart gave Mac Breen as a chief in Kilkenny, and as present in Tyrone as well.
 The O'Breens were centered in the barony of Brawney in Westmeath, where they were known as Lords of Brawney (Breaghmani) in earlier days. O'Hart" ... "gives Breen and Brawne as variant spellings of the original'O'Braoin'. This family also held land in Offaly.
 In the 17th century 'Breen' is found as a principal name of Queens County (Leix), and O'Breene is found as a principal name of Kerry, as well as being found in Wexford at that time.
 A century ago the name was found most popular in Wexford, Dublin and Keny".

Excerpts from Source: MacLysaght, Michael, Book of Irish Families Great & Small, p. 30, Vol. 1 ed 2, Irish Academic Press Ltd, Kill lane, Blackrock, Co. Dublin, Ireeland, 1997