William Heiskell (1788 – September 9, 1871) was an American politician, active primarily in Tennessee, in the mid-19th century. He served a tumultuous term as Speaker of the Tennessee House of Representatives in the months following the Civil War, where he opposed the radical agenda of Governor William G. Brownlow, most notably refusing to sign the state house's ratification of the Fourteenth Amendment in 1866. A Whig, he had previously served a single term in the Tennessee House, from 1849 to 1851.