Óengus Osrithe son of Criomthann Mór (son of Iar mac Sétnai) and his wife Cindnit, daughter of Dáire mac Degad and Morand, was the semi-legendary first king and eponymous ancestor of the Osraige people of Ireland.[1] His supposed floruit lies in the late first or early second century AD.[2]
As the founder of the kingdom, it has been regarded that his descendants took their name from him; but scholars have more recently suggested that perhaps the tribal name "Osraige" which means "people of the deer" may pre-date him and instead became his appellation.[3] He wedded Side, daughter of the druid Delbath, brother of Mogh Ruth, and is buried in the tumulus in Kilcullen, Co. Kilkenny.[4] His son and heir was Loegaire Birn Buadach, whose ruling descendants bore the tribal name "Dál Birn".
He appears in a number of surviving tribal genealogies, notably in MS Rawlinson B 502. He is named with his father, mother and maternal grandfather in the Banshenchas: "Oengus Ossory son of Cremthand, his mother was blameless Cindnit daughter of Daire Dord son of Dedad. There was a king of bloody struggles."[5]