Henry Petty-Fitzmaurice, 3rd Marquess of Lansdowne, KG, PC, FRS (2 July 1780 – 31 January 1863), known as Lord Henry Petty from 1784 to 1809, was a British statesman. In a ministerial career spanning nearly half a century, he notably served as Home Secretary and Chancellor of the Exchequer and was three times Lord President of the Council.