Ó Ceallacháin

Rev Patrick Woulfe

Ó CEALLACHÁIN—I—O'Callaghan, O'Callahan, Callaghan, Callahan, Calligan, &c.; 'descendant of Ceallachán' (diminutive of Ceallach); the name of a well-known Munster family descended from Ceallachán of Cashel, king of Munster, in the 10th century. The surname was not, however, taken from this Ceallachán, but from a namesake of his four generations later. The O'Callaghans were originally chiefs of Cinel Aodha, now the barony of Kinalea, in the south of Co. Cork, but on being driven thence by Robert FitzStephen and Milo de Cogan, soon after the Anglo-Norman invasion, they settled on the banks of the Blackwater, to the west of Mallow, where they continued to enjoy considerable possessions, known as Pobul Ui Cheallachain, comprising the parishes of Kilshannig and Clonmeen, down to the time of the Cromwellian confiscations, when the head of the family was transplanted to Clare. There is also a Mayo family of the name, a branch of the Ui Fiachrach, who were anciently lords of Erris.

Alphabetical Index to Irish Surnames