O'Connell, Frederick William (1876–1929), clergyman and Irish-language scholar, was born 22 October 1876 in Clifden, Co. Galway, son of Rev. W. Morgan O'Connell, rector of Clifden. Educated at the High School, Dublin, he entered TCD with entrance prizes in Hebrew and German and won numerous prizes during his time there. He was a Bedell scholar in 1896, a Kyle prizeman in 1897–8 and received several board prizes from 1896 to 1900. He graduated with an honours BA in modern literature in 1900 and two years later with a divinity testimonium degree. From 1901 to 1902 he edited the Irish language newspaper An tEorpach. He graduated BD (1905) and MA (stip. cond.) (1908); the following year he was fellowship prizeman in classical and Semitic philology. He graduated Litt.D. (1915) and Phil.D. (1919).
O'Connell was ordained in 1902 and became curate of Newtownforbes, Co. Longford, and the following year curate-in-charge of Drumshambo, Co. Leitrim. He was appointed rector of Castleconnor, Co. Sligo, in 1905 and two years later, rector of Achonry and canon of Kilmovee. He remained in this post until 1910 when he obtained a general licence for the united dioceses of Down, Connor, and Dromore. According to Maurice Gorham he later converted to Roman catholicism.
He was appointed the first lecturer in Celtic languages and literatures in QUB in 1909. The historians of Queen's suggest the aim of the lectureship may have been to conciliate catholic and nationalist opinion. However, on 18 July 1912 the senate of the university rejected a proposal that the lectureship should be raised to the status of a chair. He remained in the post until 1925, when he resigned because of his wife's deteriorating health. He was advising examiner in Irish to the Intermediate Board of Education (1908–13), external examiner to the NUI (1914–19 and 1923–9), and examiner in Irish to the Intermediate Board of Northern Ireland (1923).
In addition to translating morning and evening prayer, a holy communion liturgy, and a litany into Irish he published a number of academic works and essays: a translation of Cúirt a’ mhean oíche appeared under the title The midnight court (1909); Giotaí as trí bior-ghaoithe an bháis (1910); A grammar of old Irish (1912). Together with R. M. Henry (qv) he translated An Irish corpus astronomiae: being Manus O'Donnell's seventeenth century version of the Lunario of Geronymo Cortès (1915). The writings on the walls (1915) was published under the pseudonym ‘Conall Cearnach’ and according to a reviewer in the Irish Book Lover (1915–16) contained ‘pages of wit and wisdom’. Also in 1915 he published Guaire and Bricriu and once again used the name Conall Cearnach for his edition of Peadar Ó Laoghaire's (qv) Don Cíochóte (1921). Other publications include The aphorisms of Johannes Damascenus (1920); The poetry of the Koran; a collection of essays entitled The age of whitewash (1921); The fiend that walks behind (1921); a collection of essays, Old wine and new (1922); Irish self-taught (1922); The fatal move and other stories (1924) and he translated Dr Jekyll and Mr Hyde into Irish (1929). He contributed to a number of journals including Hermathena, the Gaelic Journal, Banba and the Journal of the Louth Archaeological Society. He published ‘Some thoughts on an Irish literary language’ in Studies (1923). He also worked on the Irish language dictionary prepared by the RIA. He was vice-president and foundation fellow of the Royal Institute of British Poetry (1917), fellow of the Société Internationale de Philologie, Sciences et Beaux-Arts as well as vice-president of the Celtic section of the Société (1918), member of the Royal Asiatic Society (1919), and a member of the National Academy of Ireland (1922).
In March 1927 he was appointed assistant director of broadcasting for the newly founded 2RN, where among his other duties, and because of his linguistic skills, he had charge of correspondence with foreign radio stations. On 1 January 1929 he broadcast New Year greetings in ten languages. He died accidentally when struck by a bus on Pembroke Road on 19 October 1929. He was survived by his second wife whom he had married following the death of his first wife Helen (née Young of Nenagh) with whom he had three sons and one daughter. The news of his death was reported in the Irish Times under the heading ‘Conall Cearnach’, the name he had used when he joined the Gaelic League as a young man and by which he was often known.