title: Donnell O'Brien
text: # Donnell O'Brien
  
  Donnell O'Brien may refer to
  
  * Domnall Mór Ua Briain (?–1194), king of Thomond, king of Munster, king of Limerick, 1168-1194
  * Domhnall mac Conchobair Ó Briain (?–1579), claimed the title of Earl of Thomond in 1553
  