Richard Colley Wellesley, 1st Marquess Wellesley, was an Anglo-Irish politician and colonial administrator. He was styled as Viscount Wellesley until 1781, when he succeeded his father as 2nd Earl of Mornington. In 1799, he was granted the Irish peerage title of Marquess Wellesley of Norragh. He was also Lord Wellesley in the Peerage of Great Britain.

Earl of Mornington is a title in the Peerage of Ireland. It was created in 1760 for the Anglo-Irish politician and composer Garret Wellesley, 2nd Baron Mornington. On the death of the fifth earl in 1863, it passed to the Duke of Wellington; since that date, the title has generally been used by courtesy for the heir apparent to the heir apparent to the dukedom.