Gwynn, Aubrey Osborn (1892–1983), Jesuit priest and academic, was born 17 February 1892 at Clifton, Bristol, England, the second son among six children (four boys and two girls) of Stephen Lucius Gwynn (qv), writer and MP, and his wife and first cousin, Mary Louise Gwynn, daughter of Rev. James Gwynn of Dublin and Bath. Born into an esteemed Church of Ireland family, he was the great-grandson of William Smith O'Brien (qv), the grandson of Rev. Dr John Gwynn (qv), regius professor of divinity at TCD (1888–1907), and the nephew of Edward John Gwynn (qv), provost of TCD (1927–37). On his mother's conversion to Roman catholicism (1902), Aubrey, his brother Denis Gwynn (qv), and their siblings were received into the catholic church at Farm Street, London, and brought up as catholics. Due to the nature of his father's work, much of Aubrey's early life was divided between London and Dublin.
Educated at the Jesuit Clongowes Wood College, Co. Kildare (1903–8), Gwynn spent a year of private study in Munich before becoming the first student to sign the register at the newly chartered UCD, where he later gained first-class honours (BA, 1912; MA 1915) in classics. When Fr William Delany (qv) admitted him to the Jesuit noviceship in Tullabeg, Rahan (1912), Gwynn intended to join the Chinese mission and work in Hong Kong, but under the guidance of Delany's successor, Dr T. V. Nolan, he entered academic life. After studying for a year at Rathfarnham, he went in 1916 on a travelling studentship to Oxford (Campion Hall), where he was awarded the Cromer essay prize (1917) and graduated B. Litt. (1919). He taught classics and German for two years at Clongowes (1917–19) before spending two years studying philosophy at the Jesuit College, Louvain (1919–21), and a further four years studying theology at Milltown Park, Dublin. He was ordained at Milltown Park on 24 July 1924 and trained for a final year in Exaten, the Netherlands (1926), then took his final vows in Dublin on 2 February 1929.
Initially employed (1927) as an assistant lecturer in ancient history at UCD, Gwynn replaced Daniel A. Binchy (qv) as lecturer in medieval history on the latter's appointment as Irish Free State minister in Berlin. When John Marcus O'Sullivan (qv) resumed his duties as professor of history in 1932, he was so impressed with the young lecturer's abilities that he had his position made permanent. Sixteen years later, in 1948, Gwynn was appointed first professor of medieval history. Actively involved in the administration of UCD, he was a member of the governing body, dean of the faculty of arts (1952–6), and a member of the NUI senate. He also served as president of the RIA (1958–61).
A pioneering scholar, Gwynn wrote or edited numerous contributions to ancient, medieval, and modern history, on such subjects as Roman education, Archbishop Richard Fitzralph (qv) of Armagh, and Irish emigrants in the West Indies. His many articles, numbering over one hundred, as well as his reviews, which he often initialled P. D. (‘Poor Devil’), were published in various journals, including the Journal of Hellenic Studies, Analecta Hibernica, and the Irish Ecclesiastical Record. As a member of the Irish Manuscripts Commission (1943–74) he revived the study and publication of the Calendar of Papal Letters. He was exonerated after being accused, by Regina Zukasiewicz, of stealing her deceased husband's manuscripts (1956). Despite being plagued by bouts of depression, he gained international recognition and an array of awards, among them offers of honorary doctorates from QUB (1964), and TCD (1965) – the second of which he declined. However, Gwynn was not impressed with his honorifics asserting that the only qualifications he required were SJ – alluding to his membership of the Society of Jesus.
Gwynn lived mostly with the Jesuit community at 35 Lower Leeson Street (1927–62), where he was superior of residence (1932–45). A keen supporter of the Missionary Sisters of St Columba and St Joseph's Young Priests’ Society, he helped to establish the latter's civil service branch (1930), advised on the preparing of their constitution (1945), and was editor of their quarterly magazine, St Joseph's Sheaf (1927–49). After he retired from UCD in 1961 he moved to Milltown (1962), where he lectured for two years on church history and tended to the library (1962–6). He remained active, despite failing eyesight, until a fractured femur left him in St Vincent's Hospital; he then moved to Our Lady's Hospice, Harold's Cross, where he died 18 May 1983. He was buried two days later, following funeral mass at the Jesuit church, Gardiner Street.