Ua Conchobair Fhailge, Conchobar (d. 1115), son of Congalach and joint overking of Leinster, belonged to the Uí Fhlainn lineage of the Uí Fhailge dynasty. His father Congalach, king of Uí Fhailge, a descendant of Flann dá Chongal (qv) and great-grandson of an earlier Conchobar, ancestor of the ruling line of Ua Conchobair Fhailge (O'Connor Faly), was slain in an internecine feud in 1051. His mother is not identified, but his brothers included Cú Fhaifne and perhaps also Muirchertach. Similarly, there is no record of his wife but it appears that he had at least four sons: Donnchad (slain 1092), Domnall (slain 1115), Máel-mórda, and Máel-Sechnaill.
The death of Congalach in 1051 was followed by a period of strife within Uí Fhailge in the course of which Conchobar Ua Sibléin, a dynast of the rival Clann Maíl-augrai lineage, emerged as ruler. In 1055 the latter was slain; following a protracted struggle, Conchobar's brother Muirchertach attained the kingship. Conchobar himself came to prominence from 1070, when he blinded his brother in an attempt to seize power. His ambitions received a temporary setback with the advent of another Ua Sibléin, Gilla-Pátraic, but the following year he took the kingship of Uí Fhailge by killing this adversary and several of his retainers.
Conchobar was the only Leinster ruler who seems to have maintained a degree of independence from the Munster claimant to the high-kingship of Ireland, Tairdelbach Ua Briain (qv) (d. 1167). Taking advantage of the political vacuum that followed the death of the powerful Uí Chennselaig overking of Leinster Diarmait (qv) son of Máel na mBó (qv) in 1072, and of his grandson Domnall son of Murchad three years afterwards, Conchobar dared to celebrate the Óenach Carmain (Fair of Carman, east of Kilcullen, Co. Kildare) in 1079, which amounted to a claim to overkingship of the province. Exactly how extensive his authority actually was at this stage is not clear, but the king-lists do not admit him as provincial ruler till much later. In any event, he was careful to avoid direct conflict with Ua Briain. Meanwhile, he faced a threat from the midland kingdoms of Tethbae and Cenél Cairpri, whose rulers twice invaded his realm but were defeated at Clonfert (Co. Laois) and at Killeigh (Co. Offaly) with heavy losses.
A resurgence of Uí Chennselaig power in the later 1080s obliged Conchobar to temper his ambitions, but he continued to exercise significant influence in provincial politics. The Book of Leinster maintains that he was responsible for the killing at Ráith Mór (1089) of the Uí Chennselaig overking, Donnchad son of Domnall Remur (qv); be that as it may, this action facilitated the succession of Énna son of Diarmait son of Máel na mBó. If Conchobar, or the family of Diarmait, indeed aspired to re-establish the independence of the Leinster provincial kingship, such hopes were soon stifled; Muirchertach Ua Briain (qv), who had succeeded his father as overking of Munster and claimant to the high-kingship, enforced his dominance by imprisoning Énna. The latter fell in an intra-dynastic conflict in 1092, leaving Conchobar close to his goal of attaining provincial dominance. The king-list in the Book of Ballymote names him as the next overking; again, it may be doubted that he enjoyed undisputed sway over Leinster, but it is probably significant that, the same year, Ua Briain led a hosting to secure his submission. Before the year ended, his son Donnchad was killed by his own kinsmen.
Subsequently, it appears that Conchobar joined Gofraid Méránach (qv), king of Dublin (almost certainly identical to Godred Crovan, ruler of Man and the Isles), in an alliance against the high-king. When Ua Briain marched to Dublin in 1094 to expel the Norse-Hebridean king, he imprisoned Conchobar. After his release Conchobar kept a low profile for a time, but returned to prominence in parallel with the rise of the Uí Chennselaig king Donnchad son of Murchad, father of Diarmait Mac Murchada (qv). According to both the Book of Leinster king-list and the regnal poem ‘Cúiced Lagen na lecht ríg’, he shared the provincial kingship with Donnchad. Taking advantage of Ua Briain's illness in 1114, they formed an alliance against their Munster overlords. However, in a battle fought near Dublin (1115), the allies were routed by Domnall Ua Briain, son of Muirchertach; the casualties included Conchobar (aged probably over 70) and his son, Domnall.
Conchobar was succeeded as king of Uí Fhailge by his grandson, Rogán son of Domnall, but Rogán was killed in 1118 by his great-uncle, Cú Fhaifne, who reigned till 1130. Although another grandson of Conchobar, Áed son of Domnall, and his two surviving sons Máel-mórda and Máel-Sechnaill all reigned briefly as kings of Uí Fhailge in the 1130s, most of the later rulers of the line descended from Cú Fhaifne.