Other branches of the clan: MacDonnell, Daniel, Daniels, Donnell, Danly, Donald, Donnellan, Donlan, Donnellon, Donelon, Donnal, M'Donnell, O'Donnelly.
Irish Clan Name: MacDomhnaill and Ó Domhnaill

O'Donnell is the twelfth most common name in Ireland. The most famous and powerful Sept of this Clan were the O'Donnells of Tirconnel (Tirconnaill or Tirconaill), in County of Donegal. Two other important Septs were established near Corcabask in the West of the present County Clare, and in the district formerly known as Ui Maine in County Galway. The Tirconnel O'Donnells were descended from Niall of the Nine Hostages, who died in 901 A.D. They became powerful in the thirteenth century, and their prominence in the sixteenth and seventeenth centuries was notable. As well as holding their main centre in County Donegal in the Province of Ulster, O'Donnells were found in West County Clare, and in Counties Limerick and Tipperary.

Ballinafad is part of the ancestral home of the O'Donnells and form a stage of the Beara-Breifne Greenway which is based on the historic march of O'Sullivan Beara in 1603.