Cathbarr O'Donnell

Cathbarr O'Donnell (Cathbarr Ó Domhnaill, c. 1583 - 15 September 1608) was an Irish nobleman (a member of the O'Donnell dynasty of Donegal).

Biography
Born c. 1583, Cathbarr was the son of Sir Aodh mac Maghnusa Ó Domhnaill (Sir Hugh McManus O'Donnell), An Ó Domhnaill (The O'Donnell), the ruler of Tyrconnell during the Elizabethan era. His mother was Sir Aodh's Scottish second wife, Iníon Dubh.

Cathbarr's elder half-brother, Sir Domhnaill Ó Domhnaill, was a dynastic rival of Cathbarr's elder full brother, Aodh Ruadh Ó Domhnaill II (Red Hugh O'Donnell II), in the lengthy Ó Domhnaill succession dispute until Sir Domhnaill's death at the Battle of Doire Leathan in September 1590. Aodh Ruadh II (Red Hugh II) became head of the Ó Domhnaill dynasty in 1592. Cathbarr supported his elder brother during Tyrone's Rebellion (1594–1603). In 1602, another elder brother, Rory, succeeded Aodh Ruadh and made peace with the Crown. The following year, Rory was made Earl of Tyrconnell.

Cathbarr married Rosa O'Doherty, the sister of Sir Cathaoir Ó Dochartaigh (Sir Cahir O'Doherty), Lord of Inishowen, who fought on the Crown's side during Tyrone's rebellion but later launched O'Doherty's Rebellion by burning Derry. In 1607, Cathbarr and Rosa accompanied Rory in the Flight of the Earls to Continental Europe. The following year, Cathbarr and Rory both died of fever in Italian exile and the leadership of the O'Donnells passed to Rory's young son.

After Cathbarr's death, Rosa remarried to the Irish soldier Owen Roe O'Neill. Cathbarr's son with Rosa, Hugh O'Donnell became a Captain in the Spanish Army, serving in his stepfather's regiment in Flanders. He was killed in 1625 during the Siege of Breda.