The Uí Ceinselaig (also Uí Ceinselaig, Anglicized as Kinsella), from the Old Irish "grandsons of Cennsalach", are an Irish dynasty of Leinster who trace their descent from Énnae Cennsalach, a supposed contemporary of Niall of the Nine Hostages.
The earliest associations of the Uí Ceinnselaig are with the region around Rathvilly, County Carlow, and the headwaters of the River Slaney, but in time the centre of their power was pushed southwards, later being found around Ferns, County Wexford, site of the monastery of the saint Máedóc of Ferns (d. 626 or 632).
A branch of the family, the descendants of the Uí Ceinnselaig dynast Murchad mac Diarmata meic Máel na mBó, took the surname mac Murchada (from which modern Irish Mac Murchadha, anglicised as MacMurrough, Murphy, Morrow, etc.).
[4] Another segment of the Uí Ceinnselaig family, the descendants of the Uí Ceinnselaig dynast Domnall Remar mac Mael na mBó, took the Irish surname Ua Domnaill.
[3] Notable kings of the Uí Ceinnselaig and related kindreds included: