Boleslaus of Masovia may refer to: Boleslaus IV of Poland (1122–1173), Duke of Masovia and Kujavia Boleslaus I of Masovia (1208–1248), of Masovian Piast descent Boleslaus II of Masovia (1251–1313), of Masovian Piast descent Boleslaus George II of Halych (1308–1340), of Masovian Piast descent Boleslaus III of Plock (1322–1351) Boleslaus III of Masovia (1385–1428) Boleslaus IV of Masovia (1421–1454) Boleslaus V of Masovia (died 1488)