Nicholas Vansittart, 1st Baron Bexley, PC, FRS, FSA (29 April 1766 – 8 February 1851) was an English politician, and one of the longest-serving Chancellors of the Exchequer in British history.

Vansittart began his public career by writing pamphlets in defence of the administration of William Pitt, especially on its financial side, and in May 1796 became Member of Parliament for Hastings, retaining his seat until July 1802, when he was returned for Old Sarum.

In February 1801 he was sent on a diplomatic errand to Copenhagen, and shortly after his return was appointed joint Secretary to the Treasury, a position which he retained until the resignation of Henry Addington's ministry in April 1804.

In 1809 he proposed and carried without opposition in the House of Commons thirty-eight resolutions on financial questions, and only his loyalty to Sidmouth prevented him from joining the cabinet of Spencer Perceval as Chancellor of the Exchequer in October 1809.

Nevertheless, the continuance of the Napoleonic Wars compelled him to increase the customs duties and other taxes, and in 1813 he introduced a complicated scheme for dealing with the sinking fund.

In 1816, after the conclusion of peace, a large decrease in taxation was generally desired, and there was an outcry when the Chancellor proposed only to reduce, not to abolish, the property or income tax.

He carried an elaborate scheme for handing over the payment of naval and military pensions to contractors, who would be paid a fixed annual sum for forty-five years; but no one was found willing to undertake this contract, although a modified plan on the same lines was afterwards adopted.