Count Stanislaw Malachowski, of the Nalecz coat-of-arms (Polish pronunciation: [sta'?iswaf mawa'x?fsk?i]; 1736–1809) was the first Prime Minister of Poland, a member of the Polish government's Permanent Council (Rada Nieustajaca) (1776–1780), Marshal of the Crown Courts of Justice from 1774, Crown Grand Referendary (1780–1792) and Marshal of the Four-Year Sejm (1788–1792).The son of Jan Malachowski, the royal grand chancellor, Malachowski was named marshal (speaker) of the Sejm (Diet) in 1788.
He was the prime force behind a constitution, adopted in 1791, that embodied such modern western European reforms as majority rule in parliament, separation of powers, and enfranchisement of the middle classes; this constitution was abrogated at the Second Partition of Poland in 1792.
In 1807–09 Malachowski served as president of the senate (government) of the Duchy of Warsaw, promoted by Napoleon Bonaparte.