The (First) Slovak Republic, otherwise known as the Slovak State, was a partially-recognized client state of Nazi Germany which existed between 14 March 1939 and 4 April 1945 in Central Europe. The Slovak part of Czechoslovakia declared independence with German support one day before the German occupation of Bohemia and Moravia. It controlled most of the territory of present day Slovakia, without its current southern parts, which were ceded by Czechoslovakia to Hungary in 1938. It was the first time in history that Slovakia had been a formally independent state. Bratislava was declared the capital city.

In the field of international relations, a client state, is a state that is economically, politically, and militarily subordinated to a more powerful controlling state. Alternative terms for a client state are satellite state, associated state, and dominion, condominium, self-governing colony, and neo-colony, protectorate, vassal state, puppet state, and tributary state.