Guillaume Emmanuel Guignard, vicomte de Saint-Priest (4 March 1776, in Constantinople – 29 March 1814) was a French émigré general who fought in the Russian army during the French Revolutionary Wars and the Napoleonic Wars. He was the eldest son of prominent émigré diplomat François-Emmanuel Guignard, comte de Saint-Priest (1735–1821), one of King Louis XVI of France's last ministers, and Constance Wilhelmine de Saint-Priest. Guillaume Emmanuel became a Major-General in the Russian army under Emperor Alexander I of Russia, and fought against the forces of Napoleon. Some weeks before the Battle of Leipzig, he and his cavalry finally defeated the troops of French brigade general François Basile Azemar in the Battle of Großdrebnitz. Saint-Priest was defeated and mortally wounded during the 1814 Allied invasion of France in the Battle of Reims and died two weeks later at Laon.