Therry, John Joseph (1791–1864), catholic priest in Australia, was born in Cork city, son of John Therry and Eliza Therry (née Connolly). He was educated privately and in 1812 attended St Patrick's College, Carlow. After ordination (1815) by John Thomas Troy (qv), archbishop of Dublin, he returned to Cork, where he was secretary to the bishop of Cork, John Murphy (qv). In 1818 he met the recently exiled Australian missionary Fr Jeremiah O'Flynn (1788–1831), who sparked his interest to serve as a missionary in the penal colonies. Therry approached Bishop Edward Slater, recently appointed vicar apostolic of Mauritius and Australasia, who accepted him for the mission in April 1819. Therry and a fellow Irish priest, Philip Conolly (1786–1839), received sanction from the colonial office on 20 August 1819, and were appointed colonial chaplains at an annual salary of £100 each, only a third of that of their protestant counterparts. The two priests sailed aboard the Janus, a female convict ship, and arrived in Sydney on 20 May 1820.
Soon after arrival Therry and Conolly parted ways. Conolly went to Van Diemen's Land (Tasmania), and from 1821 to 1826 Therry was the sole catholic priest in mainland Australia. He covered a large territory as an itinerant missionary to the poor (mainly convict) Irish community. He also sought to establish the catholic faith more solidly by starting catholic schools and by taking issue with the protestant government and clergy over proselytising in orphanages. He also set about immediately to build a catholic cathedral in Sydney, and obtained land from the government for this purpose. His grand design was considered overblown for such an impoverished community; however, he proceeded with his plans. The foundation stone for St Mary's cathedral was laid 29 October 1821, but lack of funds held up the completion until 1837.
Therry had a difficult and turbulent relationship with the colonial authorities, the protestant hierarchy, and his fellow catholic priests. After a misquote in the 14 June 1825 Sydney Gazette described him as having ‘qualified’ rather than ‘unqualified’ respect for protestant clergymen, he was removed from his appointment as colonial chaplain and offered £300 as payment for a passage out of Australia. However, Therry refused to leave Sydney, and remained a thorn in the side of his antagonists, both catholic and protestant. He had a strong following among the poor Irish catholic communities owing to his genuine concern and willingness to fight for their welfare. Therry's uncooperative attitude towards the official chaplains, also Irish, who had replaced him, factionalised the Irish community. However, with the advent of Bishop John Bede Polding in September 1835, Therry bowed to his authority and moved to Campbelltown at Polding's request. In 1837 his government salary was restored, and in 1838 Polding appointed him vicar general to Tasmania. When the first bishop, Dr Robert Willson, arrived in Hobart in May 1844, antagonisms arose between the two over church debts. From September 1846 to April 1847, Therry was a PP in Melbourne. He then served as parish priest in Windsor, NSW until June 1848, when he returned to Tasmania for six years. In May 1856 he went to Balmain, New South Wales, and remained an active pastor until his death 25 May 1864. His remains are in the crypt at St Mary's cathedral, Sydney, and the Lady chapel at the cathedral was erected in his memory. He was named ‘archpriest’ in 1858, and in 1859 was elected a founding fellow of the council of St John's College, University of Sydney.