Siemowit III, Duke of Masovia
Siemowit III | |
|---|---|
| Duke of Masovia | |
Princely seal of Siemowit III; 1371 | |
| Born | c. 1320 |
| Died | 16 June 1381 |
| Buried | Plock cathedral |
| Noble family | Piast |
| Spouse(s) | Euphemia of Opava Anna of Ziębice |
| Issue | Euphemia Anna Janusz I of Warsaw Margaret Siemowit IV of Masovia Henry of Masovia |
| Father | Trojden I of Masovia |
| Mother | Maria of Galicia |
Siemowit III of Masovia (alternatively Ziemowit III; c. 1320 – 1381) was a prince of Masovia and a co-regent (with his brother Casimir I of Warsaw) of the lands of Warsaw, Czersk, Rawa, Gostynin and other parts of Masovia.