Janusz I of Warsaw Polish noble (1347–1429) Parents Euphemia of Opava Siemowit III, Duke of Masovia Children Bolesław Januszowic Janusz the Younger Konrad Januszowic Siblings Euphemia of Masovia Siemowit IV Henry of Masovia Margaret of Masovia Stanisław Siemowit of Masovia Partners Danutė of Lithuania
