Ó Ceallaigh (O'Kelly), Ralph (c.1300–1361), archbishop of Cashel, was a native of Drogheda. His father, according to John Bale (qv) in his Scriptorum illustrium Maioris Brytanniae (1557–9), was David Ó Buge, a Carmelite theologian, and his mother was the wife of a Drogheda merchant, William Kellei. He had his early education in the Carmelite house in Kildare, and at some stage joined the Carmelite order. No record survives of further education in England but he appears to have studied canon law at Rome and Avignon. While in Avignon he served for two separate periods (1327–33 and 1339–44) as prolocutor and advocate general of the Carmelite order. In 1333 he was removed from office for a theological disagreement with Pope John XXII.
Probably as a reward for good service, Ó Ceallaigh was provided to the see of Leighlin in February 1344, when erroneous reports of the death of Meiler le Poer reached Avignon, and he was consecrated by the time the error was corrected. He served as suffragan in York in 1344 before being provided to the archdiocese of Cashel in January 1346, but remained in England for a time, serving as a suffragan in Winchester, before returning to Ireland. In April 1347 he was one of those appointed to inquire into the accusations made by Richard Ledrede (qv), bishop of Ossory, against Alexander Bicknor (qv), archbishop of Dublin.
Early in his time as archbishop, Ó Ceallaigh proved to be a man determined to protect the rights of his office: he denounced a levy on the clergy granted by a great council in 1347 and threatened to excommunicate any clergy within his province who paid the subsidy. After he and his suffragan bishops had excommunicated certain named officials, he was required to appear before the justiciar's court, where he pleaded unsuccessfully the church's rights under Magna Carta. The consequences of the case for Ó Ceallaigh are not known, though it clearly did not do lasting damage to his relations with government: in 1355 he was involved in arraying men to put down the Ó Ceinnéidigh revolt and four years later, at a great council at Waterford, he gave his consent to a subsidy to pay for war against Art MacMurrough (qv) (d. 1362). A dispute in 1353 with Roger Cradock, bishop of Waterford (1350–61), who had burned two men for heresy without Ó Ceallaigh's permission, led to the archbishop physically assaulting Cradock and, allegedly, robbing him of his belongings. Ó Ceallaigh was in Avignon in 1358 but later returned to Cashel, where he died 20 November 1361.