Bergin, Osborn Joseph (1873–1950), Celtic scholar and poet, was born 26 November 1873 in Cork city, one of seven children (five girls and two boys) of Osborn Robert Bergin, a provision merchant, and Sarah Bergin (née Reddin), daughter of a shopkeeper. His brother, William Bergin, became city engineer of Tientsin in China. The family was protestant, belonging at various times to presbyterian and methodist congregations, and to the Plymouth Brethren. Osborn was educated at Cork Grammar School and QCC, where he studied classics (BA 1895). When he developed an interest in the Irish language, he joined the Gaelic League and found Pádraig Ó Laoghaire (d. 1896), a national schoolteacher in Beara, west Cork, who taught him to speak, read, and write excellent Irish. Bergin was a classics teacher at Cork Grammar School (1895–7) and then worked as a lecturer in Celtic at QCC (1897–1903). In 1897, at the first Oireachtas na Gaeilge, he was awarded a gold medal for three poems in Irish. In 1904 Bergin attended the summer school of the School of Irish Learning, founded in 1903 by Kuno Meyer (qv), and was awarded a scholarship by the school in the same year. He travelled to Germany to study in Berlin under Heinrich Zimmer (qv) and in Freiburg under Rudolf Thurneysen (qv), and received his doctorate from the University of Freiburg (1906). Returning to Dublin, he took up a position with the School of Irish Learning (1906–9) before becoming the first professor of early and medieval Irish at UCD (1909–40). In November 1940 he became the first director of the School of Celtic Studies at the Dublin Institute for Advanced Studies, but resigned within a few months, with effect from July 1941, in protest over government interference in the school's affairs – a government minister had refused to sanction a proposed junior appointment in the school.
He had a long association with the RIA, following his election to membership in March 1907, and was elected to its Irish studies committee in the same year. From 1919 he was general editor of the RIA's dictionary of the Irish language. He was editor of Ériu 1909–49 and also contributed many articles; every issue between 1914 and 1938 contained at least one article by the editor. His books and scholarly editions were chiefly published by the RIA, and included Stories from Keating's History of Ireland (1909) and (with R. I. Best (qv)) an edition of the manuscript Lebor na hUidre, the ‘Book of the Dun Cow’ (1929). His Irish bardic poetry, containing Irish texts and translations, was published posthumously (1970). (These editions of texts had earlier been published individually in Studies over many years.) In collaboration with D. A. Binchy (qv) he translated and enlarged Thurneysen's important Grammar of Old Irish (1946; several reprints), and the same author's Old Irish reader (1949). He had an international reputation among philologists and historical linguists for his knowledge of the history of the Irish language; fellow countrymen regarded him as one of the leading scholars of his generation. Francis Shaw (d. 1970), professor of Old Irish in UCD 1941–70, described him as prionsa na scoláirí Gaeilge, ‘prince of Gaelic scholars’ (Beathaisnéis, 17). He received an honorary degree from NUI. Bergin also moved in literary circles. He was a friend of George Russell (qv) (‘AE’), and was an accomplished versifier in several languages. Maidean i mBéarra (1918) was a book of poems; the title poem was set to the Londonderry Air.
He died unmarried at a Dublin nursing home on 6 October 1950 and was buried in St Finbarr's cemetery, Cork. He left the valuable contents of his library – over 1,200 volumes on philology and other scholarly subjects, many with important annotations – and a collection of personal papers to the RIA. There is a portrait in UCD.