Hans Winthrop Mortimer (1734–1807) was a British property speculator and politician who sat in the House of Commons between 1775 and 1790. Mortimer was the only son of Cromwell Mortimer secretary of the Royal Society, of Topping Hall, Essex and was born on 3 May 1734. He succeeded to the estates of his father on 7 January 1752. He entered Lincoln's Inn in 1755 and was called to the bar in 1761. Sometime before 1768, he sold Topping Hall and bought Caldwell Hall, Derbyshire. Mortimer died on 26 February 1807.