William Wellesley-Pole, 3rd Earl of Mornington, GCH, PC, PC (Ire) (20 May 1763 – 22 February 1845), known as Lord Maryborough between 1821 and 1842, was an Anglo-Irish politician and an elder brother of the Duke of Wellington. His surname changed twice: he was born with the name Wesley, which he changed to Wesley-Pole following an inheritance in 1781. In 1789 the spelling was updated to Wellesley-Pole, just as other members of the family had changed Wesley to Wellesley.