Siemowit of Masovia

Siemowit of Masovia may refer to these Masovian dukes:


 * Siemowit I of Masovia (1224–1262), son of Konrad I of Masovia and his wife Agafia
 * Siemowit II of Masovia (1283–1345), son of Boleslaus II of Masovia and his first wife Sophie
 * Siemowit III of Masovia (ca. 1320–1381), son of Trojden I of Masovia and his wife Maria
 * Siemowit IV of Masovia (ca. 1352–1425 or 1426), son of Siemowit III and his wife Euphemia
 * Siemowit V of Masovia (1388–1442), son of Siemowit IV and his wife Alexandra of Lithuania
 * Siemowit VI of Masovia (1444–1462), a Duke of Masovia