William Lowndes may refer to:
William Lowndes (1652–1724), British politician and Secretary to the Treasury William Lowndes (1752-1828), British lawyer, parliamentary draftsman and Chief Commissioner of the Board of Taxes William Lowndes (congressman) (1782–1822), U.S. Congressman from South Carolina William Selby Lowndes (c. 1767–1840), British Member of Parliament William Thomas Lowndes (c. 1798–1843), English bibliographer, whose principal work was The Bibliographer’s Manual of English Literature