The Irish surname Dugan is an anglicized form of the Gaelic name Ó Dubhagáin meaning “descendant of Dubhagán,” a byname derived from dubh meaning “dark complexioned or black haired one.” 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). The name is also found in Scotland. John Dugan, prisoner of war in the Tower of London, (1413) is the first recorded Scottish namebearer. The first recorded spelling of the family name is shown to be that of John O'Dugan, author of "Topographical Poems" which was dated in County Galway in 1372. Today there are more than 22,000 bearers of the surname Dugan living in The United States.