Sir Charles MacCarthy, 1st Viscount of Muskerry (died 1641), also called Cormac Oge, especially in Irish, was from a family of Irish chieftains but acquired a noble title under English law, becoming Viscount Muskerry instead of Lord of Muskerry. He sat in the House of Lords in both Irish parliaments of King Charles I. He opposed Strafford, the king's viceroy in Ireland, and in 1641 contributed to his demise by submitting grievances to the king. Muskerry died during this mission to London and was buried in Westminster Abbey.