Fáelán (d. 738), son of Murchad and overking of Leinster, belonged to the dynasty of Uí Dúnlainge. As is the case with his brothers Dúnchad (qv) and Bran Becc, the identity of Fáelán's mother is unknown; only the mother of their half-brother Muiredach is recorded. The power struggle that followed the death of Murchad (qv) in 727 culminated in the battle of Bairenn (River Burren, Co. Carlow), where Fáelán emerged as victor over his uncle Congal son of Bróen and over Etarscél son of Cellach Cualann (qv). Political supremacy, however, eluded Fáelán for another year till he slew his brother Dúnchad at Dún Ailinne (Knockaulin, Co. Kildare). Then, as overking of Leinster, a role he was to fill for almost a decade, Fáelán married his brother's queen, Tualaith daughter of Cathal (qv) son of Finguine. This bold step seemingly represented a calculated rejection of an alliance through which the powerful Munster suzerain Cathal had sought to dominate the Leinster kingship, and raises questions about complicity on the part of Tualaith.
It is probable that for at least a few years Fáelán retained the dominance that his father and brother had asserted over southern Leinster. That being the case, Cathal's attack (albeit rather unsuccessful) on Uí Chennselaig in 732 is more readily understandable. In 735 Fáelán took the field against his father-in-law at Belach Éile (probably in Co. Carlow near the River Burren). While Munster sources claim victory for Cathal, the Annals of Ulster maintain that the southern king did well to escape from Fáelán, while the king of Osraige, an ally of Munster, was slain. It may be reasonable to view the outcome of the battle as a stand-off. Fáelán's power, however, was already in decline and he was struggling to maintain overkingship of the province against the counter claims of Uí Chennselaig ruler Áed Menn (qv) son of Colcu; the latter eventually gained the support of Flann dá Chongal (qv) of Uí Fhailge, nominally a sub-king of Fáelán. It also appears that Fáelán was forced to yield hostages to Cathal at the beginning of 738.
Shortly afterwards, Fáelán died unexpectedly – prematurely, the annalist observes. Before the year ended, his brother Bran Becc was slain at the battle of Áth Senaig, fighting in support of Áed Menn against the Uí Néill overking, Áed Allán (qv). Fáelán's only recorded son, Ruaidrí (d. 785), later reigned as overking of Leinster. His descendants, the Uí Fháeláin lineage of Uí Dúnlainge, built a regional kingship in north Co. Kildare.