Portrait of Stanislaus Augustus with an hourglass. 1793. oil on canvas by Marcello Bacciarelli (1731-1818). Stanislaw II Augustus, (Stanislaw August Poniatowski); (1732 - 1798). last King of Poland, Grand Duke of Lithuania and the last monarch of the united Polish-Lithuanian Commonwealth (1764-95). Recognized as a great patron of the arts and sciences and an initiator and firm supporter of progressive reforms