The Kingdom of Poland (Polish: Krlestwo Polskie, German: Knigreich Polen), also known informally as the Regency Kingdom of Poland (Polish: Krlestwo Regencyjne), was a short-lived polity and client state proclaimed during World War I by the German Empire and Austria-Hungary on the territories of the former Russian-ruled Congress Poland, governed at the time by the Central Powers as the Government General of Warsaw.Following the Armistice of 11 November 1918 ending World War I, in spite of the previous initial total dependence of the kingdom on its sponsors, it ultimately served against their intentions as the cornerstone proto state of the nascent Second Polish Republic, the latter composed also of territories never intended by the Central Powers to be ceded to Poland.

The Regency Council of the Kingdom of Poland (Polish: Rada Regencyjna, or Rada Regencyjna Królestwa Polskiego) was a semi-independent and temporarily appointed highest authority (head of state) in partitioned Poland during World War I. It was formed by Imperial Germany and Austria-Hungary within historically Polish lands around September 1917. The council was supposed to stay in office until the appointment of a new monarch or regent. On 7 October 1918, the Regency Council declared the independence of Poland. That same month, the council took over the command of the Polska Siła Zbrojna armed forces.