Niall Ruadh (Neill Red in English, 1164-1 July 1223) was a member of the Irish House of O'Neill, a major family that ruled Tir Eoghain (County Tyrone) during the Middle Ages. Niall Ruadh was the son of Aed in Macaem Toinlesc and the father of King Brian O'Neill, an Irish king who fought against England in a failed uprising during the 1250s.