Fáelán (d. c.645), son of Colmán Már and king of northern Leinster, was an early representative of Uí Dúnlainge and is viewed by many historians as the founder of that dynasty's fortunes. According to the genealogies, his father was Colmán son of Cairpre, and his mother was Feidelm daughter of Óengus, whose lineage of Uí Théig Chométa was associated with Cell Chométa (Kilquade, Co. Wicklow). According to the ‘Banshenchas’ (lore of women), Fáelán was married at least twice: to Sárnat daughter of Eochu, the mother of his son Conall, and to Uasal (d. 643) daughter of Suibne.
Fáelán had four brothers or half-brothers: Máel-umai, Rónán, Áed Dub (qv), who became bishop of Kildare, and Áed Finn – assuming these last two are not duplications. It has long been recognised that the early Leinster regnal list, which assigns the provincial overkingship to several of Fáelán's forebears, was recast (perhaps in the eighth century) to stress the antiquity of Uí Dúnlainge dynastic claims. On that account, it must be doubted that Fáelán's father Colmán ever reigned as king of Leinster, or that the king named Rónán (d. 624) was his brother; the latter more likely belonged to the Uí Chennselaig dynasty. Fáelán's brother Máel-umai is commemorated for his role in overthrowing the Fothairt lineage of Uí Ercáin, which may be connected with the assertion of Uí Dúnlainge dominance over Kildare. He apparently preceded Fáelán as king of Uí Dúnlainge.
The hagiography of Cóemgen (qv) of Glendalough asserts that Fáelán was placed in fosterage with the saint because of the jealousy of his stepmother; it further relates that Cóemgen brought the boy to Mo-Chonóc (qv) who foretold his future greatness. A variant of this tale, incorporated in the Life of Berach (qv) of Cluain Coirpthe, credits the latter with a role in raising the young Fáelán. Stories of the royal child and his saintly carers feature prominently in the folklore of Glendalough. Historically, however, there is reason to doubt the personal connection of Fáelán with this ecclesiastical site. There are strong indications that the Uí Máil dynasty was the dominant political interest at Glendalough into the eighth century, and that the association of Fáelán with Cóemgen, which is also reflected in the genealogies, is actually a back-projection.
There are far stronger grounds for associating Fáelán with Kildare, where the dominant position of his dynasty had been secured by at least the second quarter of the seventh century. In this regard, his cause was almost certainly advanced by his brother's victory over Uí Ercáin. Doubtless he reaped further benefits from his astute political marriage to Sárnat, daughter of Eochu; although the latter's lineage of Fothairt Fea would later be associated with the barony of Forth, Co. Carlow, its rulers may at this early date have exercised control over the Kildare area. Certainly, Fáelán's brother Áed Dub was bishop of Kildare, his nephew Óengus (son of Áed Finn) was abbot, and a more distant kinsman, Brandub son of Fiachra, held the same office. Memories of Fáelán's role in ecclesiastical affairs most likely underly the claim that the saintly Báetán son of Sinell came to Cluain Andobair (Cloney, Co. Kildare) in the fifth year of his reign. It seems clear that Kildare became a royal basilica of Uí Dúnlainge and that the Cogitosus (qv) Life of St Brigit (qv), written probably in the second half of the century, primarily reflects the interests of Fáelán's dynasty.
The year of Fáelán's succession is not ascertainable, but he had certainly come to prominence by 628, when he defeated and slew the Uí Chennselaig king Crundmáel Bolg Luatha at Duma Aichir. A marginal gloss in the Annals of Ulster at this point describes Fáelán as king of Leinster, but this can hardly reflect the true situation. Five years later (633) he was party to the slaying of Uí Máil ruler Crimthann Cualann (qv), who then held the provincial kingship, in the battle of Áth Goan, in the west of the Liffey plain, probably in Kildare. His allies at this stage included Fáilbe Flann (qv), overking of Munster, and the Clann Cholmáin ruler Conall Guthbinn, son of Suibne son of Colmán – at least according to the Annals of Tigernach (Tigernach Ua Bráein (qv)). The same source, in identifying Fáelán's wife, Uasal, as a daughter of Suibne son of Colmán, seems to strengthen the case for an alliance with Clann Cholmáin; at least one genealogical tradition, however, makes her a granddaughter of one Commán of Uí Fhothaid (a dynasty that leaves its name on the barony of Iffa and Offa, Co. Tipperary), suggesting instead political links with the Munster marchlands. Although the Leinster king-list credits Fáelán with a thirty-year reign (which, if counted from the death of his Uí Máil rival Crimthann Cualann, would bring him up to c.663), this source is not very reliable before the eighth century. There are also difficulties in relation to the annals; Fáelán is not styled king of Leinster in the main hand of the Annals of Ulster and his alleged reign is not reflected in the record. Besides, his Uí Chennselaig rival Crundmáel Erbuilg is named as provincial king at the time of his death (656).
The available evidence suggests that Fáelán's actual achievement should perhaps be viewed as his securing the kingship of Uí Dúnlainge or northern Leinster and attaining a dominance over Kildare. His death is entered in the later annals at 666, but does not feature in the Annals of Ulster. In all likelihood, it should be placed earlier – probably c.645. His son Conall is described in the genealogies as ‘king in name only’, but his descendants included Murchad (qv) son of Bran Mút, ancestor of the parallel lineages of Uí Dúnchada, Uí Fháeláin, and Uí Muiredaig.