Sir William Morgan, KB was a British Whig politician of the early 18th century. Morgan was the eldest son of John Morgan, a Whig of great political influence in Brecknockshire and Monmouthshire. He inherited the Tredegar Estate from his father in 1720, and in 1722, entered the House of Commons, being returned for both Brecon and Monmouthshire and choosing to sit for the latter. He was also, like his father, appointed Lord Lieutenant of Brecknockshire and Lord Lieutenant and custos of Monmouthshire in 1720, and also became custos of Brecknockshire in 1723.