Sir William Lewen (c. 1657 – 1722), of Ewell, Surrey, was a British merchant and Tory politician who sat in the House of Commons between 1708 and 1722.
His elder brother George set up as a merchant at Poole, while he himself went to London where he became a wine importer.
He became Master of the Haberdashers in 1709 but was one of the unsuccessful Tory candidates for a directorship of the East India Company.
He was a Colonel in the Blue Regiment of the City Militia from 1711 to 1714 and was Sheriff of London for the year 1712 to 1713.
[5] Lewen died without issue on 16 March 1722, shortly after Parliament was dissolved and was buried at St Mary Ewell.