Ó hAthartaigh
Ó hATHARTAIGH—I—O Haherty, O Harty, Harty; 'descendant of Fathartach' (same as Faghartach); a variant of Ó Fathartaigh (which see), owing to the aspiration of the initial f; shortened in the spoken language to Ó hÁrtaigh and Ó hÁrta; the name, according to Mageoghegan, of an Offaly family. At the end of the 16th century, it was common in Tipperary, Limerick, Cork and Kerry.
Alphabetical Index to Irish Surnames