The UàCeinselaig (also UàCeinselaig, Anglicized as Kinsella), from the Old Irish "grandsons of Cennsalach", are an Irish dynasty of Leinster who trace their descent from ÃÂnnae Cennsalach, a supposed contemporary of Niall of the Nine Hostages. ÃÂnda was said to be a grandson of Bressal Bélach and a first cousin of Dúnlaing mac ÃÂnda Niada, eponymous ancestor of the rival UàDúnlainge.
The earliest associations of the UàCeinnselaig 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).
In early times the kings of Leinster came from the UàCeinnselaig and the UàDúnlainge, but the UàDúnlainge came to dominate the kingship of the province, and after ÃÂed mac Colggen (d. 738) it was three hundred years until the next UàCeinnselaig king of Leinster, Diarmait mac Máel na mBó (see list of Kings of UàCheinnselaig).
A branch of the family, the descendants of the UàCeinnselaig 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.). From this branch descended Domhnall Caomhánach, founder of the Caomhánach family. Another segment of the UàCeinnselaig family, the descendants of the UàCeinnselaig dynast Domnall Remar mac Mael na mBó, took the Irish surname Ua Domnaill. Both branches—the Meic Murchada and the UàDomnaill—were bitter rivals over the kingship of UàCeinnselaig.
Notable kings of the UÃÂ Ceinnselaig and related kindreds included: