Wenceslaus I Premyslid (Czech Václav) (c. 1205–September 1253) was King of Bohemia from 1230 to 1253. Wenceslaus was the son of Ottokar I and Konstancia, daughter of Bela III, King of Hungary. He encouraged huge numbers of Germans to settle in the villages and towns around the perimeter of Bohemia and Moravia. As a sign of increasing development, courtesy of the new settlers, stone buildings began to replace wooden ones in Prague.

In 1241 Wenceslas successfully repelled a raid on Bohemia by Batu Khan, although Moravia suffered devastation at the hands of the Mongols. Wenceslas' foreign policy was based around uniting the Duchy of Austria with the Kingdom of Bohemia following the death of the last Babenberg Duke, Frederick II, at the battle of the Leitha river in 1246. Wenceslas' eldest son, Vladislav, was married to Frederick's sister Marguerite and received the homage of the Austrian barons as their future ruler. However, this prince died before he could be formally acclaimed as Duke. Wenceslas' second son Premysl Otakar then married Marguerite's kinswoman Gertrude and claimed the duchy for himself. The Austrian question was put on hiatus when in 1249 Premysl Otakar led a nobles uprising against Wenceslas. The rebellion was quelled, but Wenceslas felt it prudent to crown Otakar as 'junior King' and to give him control of Moravia. Wenceslas died in 1253 and was succeeded by his son Premysl Ottokar II.