Donagh [Donough] MacCarthy, 1st Earl of Clancarty, 2nd Viscount Muskerry (Irish: Donnchadh Mac Cárthaigh; 1594 – August, 1665) was an Irish noble. He sat in the Irish House of Commons in the Irish Parliaments of 1634 and 1639 as member for County Cork. He married Ellen (Eleanor) Butler (died April 1682), who was the younger sister of James Butler, 1st Duke of Ormonde. The Earl served as a Munster general during the Irish Confederate Wars. He was one of the ten named in Act for the Settlement of Ireland 1652 as leaders of the Royalist forces in Ireland.
On the death of his father Charles MacCarty, 1st Viscount Muskerry in 1640, Donagh inherited the title. In 1658 Charles II granted him the title of Earl of Clancarty. During most of the Wars of the Three Kingdoms, he was referred to as Viscount Muskerry.
The son of Charles and grandson of Sir Cormac MacCarthy who received English title to his lands towards the end of the 16th century Tudor conquest of Ireland, Donough MacCarthy came from the line of the MacCarthy of Muskerry dynasty based on the barony of Muskerry in what is now mid-western County Cork.
Unlike many Catholic Gaelic Irish families, these MacCarthys prospered in the Protestant English state of Ireland in the early 17th century. However, Donagh MacCarthy was forced into rebellion against this state by the events of the Irish Rebellion of 1641. The rebellion had been launched by Catholic Gaelic Irish gentry from the northern province of Ulster in October 1641. Initially, Muskerry raised an armed force of his tenants and dependants to try to maintain law and order. However, he was prompted to join the rebellion by the atrocities committed by English President of Munster, William St Leger, against the Irish Catholic population in general.