O'Molony, John (1591–1651), catholic bishop of Killaloe and confederate, was the eldest son of John O'Molony of Thomond; he had one brother, Thomas, and one sister, Margaret. Initially educated in Galway by Alexander Lynch (qv), he was subsequently taken into the household of Anthony Lynch, future bishop of Kilfenora, who continued his education. After studying for the priesthood at the Sorbonne in Paris, where he was a contemporary of Malachy O'Queely (qv), he was conferred a bachelor, and subsequently a master, of theology (to be followed in due course by a doctorate in divinity), and then retired to the environs of Paris. Awarded the chair of philosophy at the Grassins in 1615, where he lectured for the next five years, he was appointed procurator of the Germanic nation at the Sorbonne in 1620 with special responsibility for students from northern and eastern Europe. Given his status in the university, it is likely that he acted as intermediary with the college authorities during the campaign for the establishment of an Irish seminary in Paris. Partly influenced by concerns for lands that he owned in his native barony, he decided to return to Ireland around 1625. He became a candidate for the bishopric of Killaloe, in competition with O'Queely, who had been vicar apostolic of the diocese since 1622. Despite the latter's large body of support, including the earl of Tyrone, O'Molony, was appointed to the see in 1630, aided by the intervention of the French queen mother. He was consecrated in Paris by the bishop of Auxerre, and began his episcopal work in 1631.
A committed albeit somewhat controversial bishop, he adopted a strategy of strict discipline to reform a hitherto neglected diocese. He was subjected to accusations of financial and moral impropriety, allegations that were ultimately dismissed by Rome, and he also became embroiled in a dispute with Thomas Walsh (qv), archbishop of Cashel, though the two men were reconciled in 1639. O'Molony's experiences in the 1640s were dominated by his consistent, though relatively low-profile, involvement with the Catholic Confederate Association. He attended the meeting of the catholic clergy and laity at Kilkenny in May 1642, and was subsequently a member of the four confederate general assemblies. He also actively supported the military effort, by financing soldiers and contributing to the war chest, and sided with the papal nuncio, GianBattista Rinuccini (qv), in rejecting the first Ormond peace in 1646. O'Molony continued to support the nuncio after the association split over the Inchiquin truce. He and Walsh petitioned Ulick Burke (qv), 5th earl of Clanricard, to take command of the Connacht army in June 1649. O'Molony attended the meeting in August 1650 at Jamestown that promulgated decrees repudiating the authority of the Stuart viceroy, James Butler (qv), marquess of Ormond. He raised a troop of men to attack Ormond at Clare, but was captured at Quin carrying £1,400. He was released at the earl's behest, and then travelled to Limerick, where he was among those clerics preaching resistance during Ireton's (qv) siege of the city. He nursed plague victims and encouraged soldiers for six months, personally maintaining an entire garrison for two weeks. Due to his actions, he was one of three bishops exempted from pardon at the fall of Limerick.
O'Molony caught plague in 1651, on the day the terms of surrender were signed – 27 October – and died shortly afterwards. No trace of his grave remains. His nephew, also John O'Molony, became bishop of Killaloe and Limerick.