O'Connor, John (John of St Dominic ) (d. 1678), Dominican priest and scholar, was a filius of Galway and was educated in Spain. From the early 1630s, while stationed at Segovia, he organised the collection of theological books (and alms for their purchase) in Spain for transport to Ireland. This he did at the bidding of William Fitzgerald OP, procurator in Madrid, and the Irish Dominican provincial, Nicholas Lynch (qv). Two memorials submitted to Philip IV of Spain provide fascinating details of this enlightened scheme. Many shipments left the ports of Bilbao, San Sebastián, and La Coruña. Subsequently they were landed on the west coast of Ireland (1636–49), often on Inishbofin and other islands in Clew Bay, whence they were distributed to the network of Dominican houses. From c.1640, as procurator at the court of Madrid, O'Connor continued this work ever more energetically. Some of the books, with inscriptions and autograph signatures, survive in Irish libraries and elsewhere.
From 1659 O'Connor was resident as procurator at Rome, where he maintained his Spanish connections. Eleonora Piementel, noblewoman and one of his penitents in Spain, arrived in Rome in 1662 after her marriage to Duke Francesco Gaetani and became his influential patron. In July 1667 he obtained permission from Giovanni Battista de Marinis, master general of the Dominican order, to establish a house of studies for Irish, English, and Scottish Dominicans at Madrid, and to accept other houses in Europe for the same purpose. To this end, he had gathered 50,000 scudi from noble donors. The decision was confirmed by Pope Clement IX (6 September 1667), who stipulated that all foundations were to come jurisdictionally under the Irish provincial, and by Clement X (6 August 1674), who ordered that its provisions be carried into effect. O'Connor was also associated (March 1668) with the short-lived Irish house in Tangiers. (Tangiers and Bombay had come to Charles II as part of Catherine of Braganza's dowry.) The master general commented (August 1668) that O'Connor would not have prevailed on him nor on Pope Clement IX but for the power of the king of Spain. Nonetheless, O'Connor received exceptional authority over all Irish Dominicans on the continent and was styled Irish procurator and vicar of the missionaries of England, Scotland, and Ireland.
About 1669–70, as procurator and commissary for England, O'Connor requested of Propaganda Fide that a house of study be established at Rome for Irish and English Dominicans; he also complained that his work in procuring books and other requirements for Dominicans in Ireland was being impeded by unnamed parties. He sought papal intervention to deflect harassment by any state or ecclesiastical officials in a task he had been pursuing for about forty years. While attending the order's general chapter at Rome (1670) he had the issue discussed, and on the same occasion was awarded the mastership in theology. He was named prior of San Sisto in Rome on 14 December 1670, but was replaced in 1671. Late in 1676 the Spanish authorities rejected his proposal for a house at Almagro (Almager), but offered to finance one at Madrid. O'Connor finally achieved the founding of a house of study when on 4 August 1677 the twin convents of SS Sixtus and Clement in Rome were formally handed over to the Irish Dominicans; O'Connor was appointed their first vicar and administrator. The simultaneous transfer of SS John and Paul to the English Dominicans was in large measure due to him and Thomas Howard OP, who had been appointed cardinal in 1675. O'Connor signed a testimonial at San Clemente as ‘overseas vicar of the Irish province’ in November 1677. In September 1678 the Irish provincial chapter protested against his ‘arrogation’ of authority over Holy Cross College, Louvain. He died in December 1678 at the Roman palace of the Duchess Gaetani and was buried at San Sisto in a grave still unmarked in 1756 (as noted by Burke).
John O'Connor, devout and austere, was a thoroughly cosmopolitan European priest of very considerable talents. His noble patrons supported him generously and unreservedly as he pursued his objectives, with singled-mindedness and perseverance, in seeking to found colleges and to promote the intellectual formation of his confrères in Ireland and abroad. For 300 years the Collegio di S. Clemente remained his monument.