This is an anglicized form of the Olde Gaelic name O Dubhagain. The Gaelic prefix "O" means "grandson" or "male descendant (of)" and the personal name "Dubhagan" the first element of which derives from the Gaelic "dubh" meaning "black" or "dark" and the diminutive suffix "an". The principal O'Dugan or Duggan clan belonged to the Irish province of Munster, especially to counties Cork, Tipperary and Waterford. In pre-Norman times, its chief was Lord of Roche's Country (on the borders of Cork and Tipperary). The other notable clan or sept belonged to the ancient Irish territory or Ui Maine (now mid Galway and South Roscommon). They gave their name to Bally (from "baile" a "town") Duggan near Loughrea in Co. Galway. The first recorded spelling of the family name is shown to be that of John O'Dugan, author of "Topographical Poems". which was dated Deceased 1372 - mid Co.Galway. during the reign of King Edward 111, known as "The Father of the Navy", 1327 - 1377. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.