Leading authority on Irish dialects and mediaeval and modern Irish, born in Listowel, Co. Kerry in 1883. Educated at the School of Irish Learning in Dublin, graduating with a degree from the Royal University of Ireland in 1905. Member of the Royal Irish Academy and Professor of Irish at Trinity College Dublin (1919-29), research Professor of Celtic languages, University College Cork (1929-35) and later at University College Dublin (1935-41), Director of the School of Celtic Studies at the Dublin Institute for Advanced Studies (1942-47). Founder and Editor of the journal, 'Gadelica'.
Principal publications included 'Early Irish History and Mythology' (1946), 'Irish Dialects, Past and Present' (1932), 'The Two St. Patricks' (1942) in addition to a series of anthologies of Irish Verse published between 1916 and 1927. He died in Dublin in November 1953.
From the guide to the Thomas Francis O'Rahilly Papers, 1849-1952, (Queen's University, Belfast)