The Countess of Rosse is a title in the peerage of Ireland, traditionally held by the wife of the Earl of Rosse. The title has a rich history, with the first creation in 1822. The Countess often plays a ceremonial role in Irish society and may be involved in charitable activities. The Earl of Rosse is known for his contributions to astronomy, particularly through the construction of the Leviathan of Parsonstown, a large telescope built in the 19th century. The title and its associated estate, Birr Castle, are located in County Offaly, Ireland.