Ó Donnchadha, Tadhg (‘Torna’) (1874–1949), professor of Irish, was born 4 September 1874 in Cork, one of three sons and a daughter of Donnchadh Ó Donnchadha, farmer, and Síle (Julia) Ní Donnchadha (née Hegarty). He attended North Monastery school in Cork, and in 1892 went to St Patrick's College, Drumcondra, Dublin. He worked for a time as a teacher in Dublin, including a time in Eccles St. He was also very involved in events surrounding the Irish-language revival and gave classes in the city through 1893 and 1894. He was a founding member of the militantly separatist Keating branch of the Gaelic League in Dublin and also edited the journal Banba for a time. In 1902 he became editor of Irisleabhar na Gaeilge, a position he held until 1909, when the Gaelic League suddenly decided to cease its publication and he was left without work.
He used his new-found freedom to travel to Heidelberg University to study Old Irish under Ludwig Mulhausen (who was later in charge of German broadcasts to Ireland during the second world war). He was already knowledgeable of the various Celtic languages, as well as German and French. On his return to Ireland he was appointed professor of Irish at St Patrick's College, Drumcondra, Dublin. Then, in 1916, he was appointed professor of Irish at UCC, a position he held until 1944. He was perceived as something of an official spokesman for the revival movement for many years. A passionate advocate of the Irish-Ireland ideal, he once equated the cinema with ‘paganism and filth’. He pushed a campaign through the 1920s promoting the number of courses in UCC taught through Irish, believing that fostering the use of Irish among third-level students was critical to the revival of the language. His efforts drew only modest success.
In 1947 Féilscríbhinn Torna, a Festschrift edited by Séamus Pender (1906–90), was published; it includes a catalogue of the fifty books and 500 pieces of poetry that he wrote or translated. This includes Leoithne andeas (1905), his first book of poetry. His first published poem was ‘Iarghnó ar bhás Sheagháin Pléimionn’ in Irisleabhar na Gaeilge (March 1896). A year later he won a poetry prize at the first Oireachtas competition. He also wrote numerous scholarly books on Irish writers. His brothers were Canon Denis Ó Donoghue (1886–1962), PP of Bandon, Co. Cork, who edited Filíocht Mháire Bhuidhe Ní Laoighaire (1931), and Éamon Ó Donnchadha, who worked in the Irish department at UCC. He died on 21 October 1949. He married Nóra Ní Fhoghluda (d. 1925),