Conn McCalvagh O'Donnell[1] (died 13 March 1583)[2] was a member of the O'Donnell dynasty of Donegal.[3] At various points in his turbulent career, Conn either opposed or allied himself with the English Crown, Shane O'Neill or Turlough Luineach O'Neill, as the situation and his personal advantage dictated in order to pursue his rivalry with his father's younger brother, Hugh mac Manus O'Donnell.