The Kingdom of Poland, also known informally as the Regency Kingdom of Poland, was a short-lived polity that was proclaimed during World War I by the German Empire and Austria-Hungary on 5 November 1916 on the territories of formerly Russian-ruled Congress Poland held by the Central Powers as the Government General of Warsaw and which became active on 14 January 1917. It was subsequently transformed between 7 October 1918 and 22 November 1918 into the independent Second Polish Republic, the customary ceremonial founding date of the latter being later set at 11 November 1918.

Congress Poland, Congress Kingdom of Poland, or Russian Poland, formally known as the Kingdom of Poland, was a polity created in 1815 by the Congress of Vienna as a semi-autonomous Polish state, a successor to Napoleon's Duchy of Warsaw. It was established when the French ceded a part of Polish territory to the Russian Empire following France's defeat in the Napoleonic Wars. In 1915, during World War I, it was replaced by the German-controlled nominal Regency Kingdom until Poland regained independence in 1918.