Władysław I of Masovia Polish noble (1389–1455) Parents Alexandra of Lithuania Siemowit IV Children Siemowit VI of Masovia Władysław II of Masovia Siblings Trojden II of Płock Jadwiga of Masovia Amelia of Masovia Cymburgis of Masovia Casimir II of Masovia Catherine of Masovia Euphemia of Masovia Siemowit V of Masovia Maria of Masovia Anna of Masovia Aleksander Mazowiecki Partners Anna of Oleśnica