O'Carroll (Ó Cearbhaill), Maolruanaidh (d. 1443), king of Éile (Ely O'Carroll), was the son of Tadhg Ailbhe O'Carroll (qv), king of Éile, and either Johanna, daughter of James Butler (qv), 2nd earl of Ormond, or Mór, daughter of Brian Sreamach O'Brien (qv) of Thomond. On the death of Tadhg (9 September 1407) it appears that Maolruanaidh succeeded his father as king of Éile. The first twenty-five years of his reign proved uneventful, as nothing is mentioned in the annals relating to it or him. This changed in 1432, when James Butler (qv) (d. 1452), 4th earl of Ormond, returned from England and set about repairing his political position, which during his absence (1429–32) had become frayed under continual attack. And from Ormond's reaction it appears that Maolruanaidh and his kinsmen played no small part in this process. Indeed, the Four Masters record in 1432 that Éile bore the brunt of Ormond's ire, when Butler forces and Donnchadh MacMurrough (qv) (d. 1478), king of Leinster, invaded the midlands and the O'Carroll homeland. From the evidence, they defeated Maolruanaidh and broke down two of his castles, forcing him to recognise Butler hegemony. In spite of this dispute, Ormond and Maolruanaidh steadily tailored their ambitions to suit their common ends: Ormond was determined to shore up his position in west Leinster and the midlands, and the O'Carrolls were at the heart of his new midland policy. Thus, Ormond ensured the future O'Carroll attachment to the Butlers, contracting a double marriage alliance with the family of Maolruanaidh. Playing an important role in Ormond's plans was the Butler family of Polestown, whose significance was the location of their manor astride the strategic junction from Gowran and Kilkenny to Carlow. They were very much a frontier family, living on the pressurised northern frontiers of the Ormond earldom, facing the O'Carrolls as well as the MacGillapatricks and the O'Mores. For Ormond, it was therefore imperative that the Butlers of Polestown conclude marriage alliances to stabilise the northern borders. About 1440 Edmund MacRichard Butler (qv) of Polestown and his sister Mary respectively married Gylys (Catherine) and Seaán O'Carroll (Ó Cearbhaill) (d. 1489), the children of Maolruanaidh. The drawing of Seaán into the Butler nexus reveals long-term planning, as he succeeded Maolruanaidh as king of Éile in 1443 on the latter's death. The O'Carroll alliance also drew the Butlers closer to the O'Connor Falys, O'Kennedys, and MacGeoghegans, the kinsmen of the O'Carrolls. Seaán's succession to the leadership of the O'Carrolls in 1443 was disputed. Some of his sons were virulently opposed to the Butler alliance and were determined to shake off the hold of Ormond. Unsurprisingly, the O'Carroll malcontents joined a confederation of O'Mores, MacGillapatricks, FitzGeralds of Kildare, and O'Connors of Offaly to attack the Butler earldom in 1443. However, their opposition was ruthlessly stamped out when Edmund MacRichard routed their expedition. This victory paved the way for a long-lasting rapprochement between Seaán and the Butlers. Indeed, Seaán was probably the ‘John O'Carroll’ recorded in the 1460s as receiving sums of money from John Butler (qv), the exiled 6th earl of Ormond. Moreover, Seaán further displayed his attachment to the earls of Ormond as FitzGerald power became stronger in the 1480s. Then he was faced by the steady advance into the midlands of the influence of Gerald FitzGerald (qv) (d. 1513), 8th earl of Kildare. In 1487 Seaán outlined to Thomas Butler (qv), 7th earl of Ormond, the danger posed by Kildare to his kingdom, writing that he was preparing to resist Kildare with his own forces and 200 hired gallowglass. Clearly Seaán was also one of the main movers behind what has become known as ‘the Anti-Geraldine League’. According to his letter, he had the support of the O'Briens, MacWilliam Burkes, MacDermots, O'Kennedys, O'Dwyers, Mac Briain of Coonagh, and Cormac MacCarthy Mór, and had promised to rouse the O'Mores to resist the Kildare advance. Seaán had every right to fear the FitzGeralds. In 1489 it was the FitzGeralds of Desmond who invaded Éile, killing him and routing his hired MacSweeney gallowglass. He was succeeded by his son, Maolruanaidh Mór O'Carroll (qv).
AFM, iv, 790–91, 973, 1166–7, 1171; John O'Donovan (ed.), ‘MacFirbis annals’, Miscellany of Irish Archaeological Society, 201; Ormond deeds, iii, 175; iv, no. 9, 315–16; Gilbert, Viceroys, 315; Liz Fitzpatrick, ‘Mairgréag an Einigh Ó Cearbhaill – the best of the women of the Gaedhil’, Kildare Arch. Soc. Jn., xviii (1992–3), 20–38; Cormac Ó Cléirigh, ‘The O'Connor Faly lordship of Offaly, 1395–1513’, RIA Proc., xcvi C (1996), 90–93