Ímar Ua Donnubáin
Ímar Ua Donnubáin or Ivor O'Donovan, and possibly nicknamed Gilla Riabach, was a legendary and celebrated petty king, navigator, trader, and reputed necromancer of 13th century Ireland belonging to the O'Donovan family. He may or may not have been the second son of Cathal, son of Crom Ua Donnubáin, from whom the modern Clancahill dynasty descend.