Earl of Bessborough is a title in the Peerage of Ireland. It was created in 1739 for Brabazon Ponsonby, 2nd Viscount Duncannon, who had previously represented Newtownards and County Kildare in the Irish House of Commons. In 1749 he was given the additional title of Baron Ponsonby of Sysonby, in the County of Leicester, in the Peerage of Great Britain, which entitled him to a seat in the British House of Lords. The titles Viscount Duncannon, of the fort of Duncannon in the County of Wexford, and Baron Bessborough, of Bessborough, Piltown, in the County of Kilkenny, had been created in the Peerage of Ireland in 1723 and 1721 respectively for Lord Bessborough's father William Ponsonby, who had earlier represented County Kilkenny in the Irish House of Commons.