Conchobar (d. 973), son of Tadc and overking of Connacht, belonged to Síl Muiredaig, a lineage of the Uí Briúin Aí dynasty. His father, known as Tadc in Túir (of the tower), had held the overkingship, but died in 956 leaving a province wracked by internal strife. Supremacy was claimed by Fergal (qv) grandson of Ruarc of the rival dynasty of Uí Briúin Bréifne. Meanwhile, Conchobar had inherited marriage-alliances with the principal dynasties of the Uí Néill: his sister Bébinn was wife to the king of Brega, Domnall son of Congalach Cnogba (qv), while another sister, Muirgel, was married into the Cenél Conaill. It was his brother-in-law Domnall son of Congalach who slew Fergal grandson of Ruarc in 966, leaving the way clear for Conchobar to assume overkingship of Connacht. The new provincial ruler, however, was not to enjoy an untroubled reign.
A son of Conchobar, described as ‘grandson of Tadc’ and styled rígdamna Connacht (eligible for the kingship of Connacht), was slain in 967; significantly, he was supporting Cenél Conaill, his aunt's kinfolk-in-law, against their dynastic rivals Cenél nÉogain. Throughout this time, Conchobar was threatened by the dynasty of Bréifne; in 970 he defeated and slew Ualgarc grandson of Ruarc, a kinsman of Fergal. Three years later Conchobar died, apparently of colic (Book of Leinster). Conchobar's immediate successor was Cathal, probably his brother, who was killed shortly afterwards (the Book of Leinster says after three days) by Murchad grandson of Flaithbertach, king of Cenél nÉogain, in the battle of Céis Chorainn. It seems that the provincial kingship remained weak for the next twenty years, as dynasts from several different lines extended their sway over parts of Connacht. However, through his son Cathal (qv) who eventually emerged as provincial ruler, Conchobar became the ancestor of the royal line of Ua Conchobair (O'Connor), which provided most of the later kings of Connacht.