Clan O'Dea [usually pronounce "ooh-day", though "oh-dee" is sometimes accepted], or Ó Déaghaidh or Ua Déaghaidh/ Ó Deá (in Irish), is a family descended from Déaghaidh, a tenth century AD Irish chieftain. The clan came originally from County Clare, Ireland. Clan descendants may have the surnames Day, O'Day, Dee, O'Dee, O'Dea, or Dea.