Clare Barrett is an Irish clan, originally descended from Normans, which includes various septs including MacPadine, MacWattin, MacEvilly (Mac an Mhileadha), and MacAndrew.
The Barrett clan descended from the Normans, and trace their ancestry to a John Baret, mentioned in the Domesday book, who settled in Pendyne in Wales after the Norman Conquest.
The Barretts then migrated to Ireland with the Norman warlord Strongbow (Richard Le Clare, the 2nd Earl of Pembroke) as hired mercenaries at the end of the twelfth century in the Norman Invasion of Ireland.
There are two Barrett clans in Ireland, the first branch of the clan are the Munster Barretts of County Cork, and the other branch is the Barrett clan of Connacht, most numerous in the Mayo-Galway mountainous areas. The two clans were believed to be unrelated before recent research proved otherwise. The English pipe rolls of the 13th century clearly indicate that the overlords of both the Cork and the Mayo Barretts were the same people, and the records further indicate that both families came from Wales. To this day, the Barretts and the Barrys of Connacht are known as "the Welshmen of Tirawley".
The similarity of the names of the two Barrett clans was thought purely coincidental. The view prevailed that the Barretts of Cork derived their name from the Norman-French "Barratt," while the Barretts of Connacht derived their name from the gaelic name "Bairéad" which means quarrelsome or warlike. Both branches of the Barrett clans were fully assimilated into Irish culture and married into many old Irish families, they are said to have become "more Irish than the Irish themselves". The chief of the Tirawley Barretts was for centuries known by the Gaelic name Mac Baitín, or Mac Wattin, which eventually evolved into Mac Páidín, or Mac Padine. This is the source of the Padden surname found in Mayo today.