Zvíkov (, ), often called "the king of Czech castles", is a castle located at the junction of the Vltava and Otava rivers, some 15 km north of Písek, in the South Bohemian Region, Czech Republic, next to the village of Zvíkovské Podhradí. It stands on a difficult-to-access and steep promontory above the confluence of the Vltava and Otava rivers. The castle is one of the most important early-Gothic castles in Czech lands.