Stanisław I Leszczyński (Polish pronunciation: [staˈɲiswaf lɛʂˈtʂɨj̃skʲi]; Lithuanian: Stanislovas Leščinskis; French: Stanislas Leszczynski; 20 October 1677 – 23 February 1766), also Anglicized and Latinized as Stanislaus I, was King of Poland, Grand Duke of Lithuania, Duke of Lorraine and a count of the Holy Roman Empire.

In 1709, Charles XII of Sweden suffered a defeat by the Russians at the Battle of Poltava, and was subsequently driven into exile in the Ottoman Empire. As a result, Stanisław lost all stable support. Augustus II ultimately became King of Poland, and Stanisław fled the country and settled in the province of Alsace, France. In 1725, his daughter Marie Leszczyńska married Louis XV of France.In Nancy, France, Place Stanislas (Stanisław Square) was named in his honour.