Beresford, Lord John George de la Poer (1773–1862), Church of Ireland archbishop of Armagh, was born 22 November 1773 in Tyrone House, Dublin, third son (among four sons and two daughters) of George de la Poer Beresford (1735–1800), 2nd earl of Tyrone and 1st marquess of Waterford, and Elizabeth Beresford (née Monck) of Charleville, granddaughter of the 1st duke of Portland. He was educated at Eton and Christ Church, Oxford (BA 1793, MA 1796, and DD (by diploma) 1805). He was ordained deacon (1795) and priest (1797) in St Kevin's church, Dublin, and preferred to the family rectories of Clonegam and Newtown Lenen in the diocese of Lismore. In 1799 he was presented to the deanery of Clogher and in 1801 became rector of Termonmaguirk in the diocese of Armagh. On 20 February 1805 he was appointed to the bishopric of Cork and Ross, and was consecrated in St Patrick's cathedral, Dublin (24 March). He was translated to the see of Raphoe (10 August 1807) and then to Clogher (25 September 1819). On 21 April 1820 he was created archbishop of Dublin and on 17 June 1822 was translated to Armagh, which was united to Clogher in 1850. As archbishop of Dublin he was appointed a privy councillor, and as archbishop of Armagh he became prelate of the order of St Patrick (to which he was invested 27 July 1822), lord almoner to the queen, and first chairman of the ecclesiastical commissioners (established by the Church Temporalities (Ireland) Act, 1833).
In 1829 he became vice-chancellor of the university of Dublin; he succeeded to the chancellorship in 1851. He was a generous benefactor of the university, presenting the Book of Armagh to the library, funding the building of a campanile in Front Square, and endowing a chair of ecclesiastical history. He also contributed to the foundation of St Columba's College, near Stackallan, Co. Meath (opened in 1844 as a school for the gentry of Ireland on the model of Eton), and to the Royal School, Armagh. He largely financed the restoration of Armagh cathedral (reopened in 1840), and contributed liberally to the augmentation of clerical stipends, while during the tithe war of the 1830s his generosity saved many clergy and their families from starvation. He was a conservative in politics, supporting the Church Education Society – the Church of Ireland response to the system of national education – and opposing the Roman Catholic relief bill of 1829, against which he spoke in the house of lords. His speech on that occasion, together with one on national education, a sermon, a charge to the clergy of Armagh, and a letter on the church discipline bill, are his only publications.
He died, unmarried, 18 July 1862 at Woburn near Donaghadee (the residence of George Dunbar, who had married one of his nieces), and was buried in the crypt of Armagh cathedral on 30 July. The funeral, which was attended by the Roman Catholic primate, Joseph Dixon (qv), and the moderator of the general assembly of the presbyterian church, Henry Cooke (qv), was marshalled by Ulster King of Arms and recorded in the books of funeral entries in his office. Beresford is commemorated in a memorial by Baron Marochetti in the nave of Armagh cathedral, in a window in the south transept which was erected by public subscription, and in the east window of Clogher cathedral. His portrait by Catterson Smith (qv), dressed as chancellor of the university, hangs in the dining hall of TCD, and a portrait of him in clerical robes, by E. R. Eddis, is in the synod hall, Armagh. His considerable archive was dispersed after his death by the dean of Down, W. P. Carmody. The principal parts of the collection are now in the public library, Armagh; the representative church body library; TCD; and the PRONI.