Duke of Masovia
# Duke of Masovia

Duke of Masovia (Polish: Książę Mazowsza) was a title borne by the sons and descendants of the Polish Duke Bolesław III Wrymouth. In accordance with the last will and testament of Bolesław, upon his death his lands were divided into four to five hereditary provinces distributed among his sons, and a royal province of Kraków reserved for the eldest, who was to be High Duke of all Poland. This was known as the fragmentation of Poland. Subsequent developments lead to further splintering of the duchies.

The following is a list of all rulers of the Duchy of Masovia and its parts. Although not all incumbents listed here had titular rights to the title of Duke of Masovia, they are all listed as such for simplicity's sake.

Also take note that some of the dates are merely approximate and the ownership of certain lands might be disputed. Finally, this table does not include lands ruled by dukes of other parts of partitioned Poland or Wenceslaus II and Wenceslaus III.

## Duchy of Masovia

### Partitions of Masovia

The Duchy went through various border changes in the coming years, sometimes losing and sometimes gaining territory.

Duchy of Masovia (1st creation) (1138-1275) :

| Duchy of Czersk (1st creation) (1275-1294) | Duchy of Czersk (1st creation) (1275-1294) | Duchy of Czersk (1st creation) (1275-1294) | Duchy of Czersk (1st creation) (1275-1294) | Duchy of Czersk (1st creation) (1275-1294) | Duchy of Czersk (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) | Duchy of Płock (1st creation) (1275-1294) |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| Duchy of Masovia (Płock line; 2nd creation) (1294-1313) |||||||||||||||
| Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Warsaw (1st creation) (1313-1355) | Duchy of Rawa (1st creation) (1313-1355) | Duchy of Rawa (1st creation) (1313-1355) | Duchy of Rawa (1st creation) (1313-1355) | Duchy of Płock (2nd creation) (1313-1351) | Duchy of Płock (2nd creation) (1313-1351) | Duchy of Płock (2nd creation) (1313-1351) | Duchy of Płock (2nd creation) (1313-1351) | Duchy of Płock (2nd creation) (1313-1351) | Duchy of Płock (2nd creation) (1313-1351) |
| Annexed to Poland (1355-1370) ||||||
| Annexed to Poland (1355-1370) |||||||||
| Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Płock (3rd creation) (1381-1462) | Duchy of Płock (3rd creation) (1381-1462) | Duchy of Płock (3rd creation) (1381-1462) | Duchy of Płock (3rd creation) (1381-1462) | Duchy of Płock (3rd creation) (1381-1462) | Duchy of Płock (3rd creation) (1381-1462) |
| Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Warsaw (2nd creation) (1381-1495) | Duchy of Rawa (2nd creation) (1426/34-1442) | Duchy of Rawa (2nd creation) (1426/34-1442) | | | Duchy of Bełz (1426/34-1442) | Duchy of Bełz (1426/34-1442) |
| Duchy of Czersk (2nd creation) (1471-1495) | Duchy of Czersk (2nd creation) (1471-1495) | Duchy of Czersk (2nd creation) (1471-1495) | Duchy of Czersk (2nd creation) (1471-1495) | Duchy of Czersk (2nd creation) (1471-1495) | | | | | | Duchy of Płock (4th creation) (1471-1495) | Duchy of Płock (4th creation) (1471-1495) | Duchy of Płock (4th creation) (1471-1495) | Duchy of Płock (4th creation) (1471-1495) | Duchy of Płock (4th creation) (1471-1495) |
| Duchy of Masovia (Czersk line; 4th creation) (1495-1526) |||||||||||||||

### Dukes of Masovia

**Piast Dynasty**

| Ruler | Ruler | Born | Reign | Death | Ruling Part | Consort | Notes |
| - | - | - | - | - | - | - | - |
| Boleslaus (I) the Curly | | 1125 | 1138-1173 | 5 January 1173 | Masovia | Viacheslava Vsevolodovna of Novgorod 1138 three children Maria after 1160 no children | Son of Bolesław III Wrymouth of Poland. Also Duke of Silesia and monarch of Poland. |
| Leszek I | | 1162 | 1173-1186 | 1186 | Masovia | Unmarried | Son of Bolesław the Curly. |
| Casimir (II) the Just | | 1138 | 1186-1194 | 5 May 1194 | Masovia | Helen of Znojmo 1163 seven children | Son of Bolesław III Wrymouth of Poland. Also monarch of Poland. |
| Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Regency of Helen of Znojmo (1194-1200) | Son of Casimir the Just. Also monarch of Poland, after his abdication of Masovia to his brother Conrad, in 1200, shortly after reaching majority. |
| Leszek II the White | | 1184/5 | 1194-1200 | 24 November 1227 | Masovia | Grimislava Ingvarevna of Lutsk between 1208 and 1211 three children | Son of Casimir the Just. Also monarch of Poland, after his abdication of Masovia to his brother Conrad, in 1200, shortly after reaching majority. |
| Conrad I | | 1187/8 | 1200-1247 | 31 August 1247 | Masovia | Agafia Yaroslavna of Peremyshl between 1207 and 1210 ten children | Son of Casimir the Just. Also monarch of Poland. |
| Boleslaus I | | 1208 | 1247-1248 | 25 February 1248 | Masovia | Gertrude of Lower Silesia 1232 no children Anastasia Alexandrovna of Belz between 1245 and July 1247 no children | Son of Conrad I. Died without descendants. |
| Siemowit I | | 1224/8 | 1248-1262 | 23 June 1262 | Masovia | Pereyaslava Danilovna of Halych 1248 three children | Brother of Bolesław I. Killed in a battle against the Lithuanians, who also took his heir prisoner. |
| Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Regencies of Pereyaslava Danilovna of Halych and Boleslaus, Duke of Greater Poland (1262-1264) | Released after two years of captivity. In 1275 divided the land with his brother Bolesław. After the division of the duchy he received Czersk. His death without male heirs allowed his brother to reunite the Duchy. |
| Conrad II | | 1250 | 1264-1275 | 24 June or 21 December 1294 | Masovia | Hedwig of Legnica 1265/70 one child | Released after two years of captivity. In 1275 divided the land with his brother Bolesław. After the division of the duchy he received Czersk. His death without male heirs allowed his brother to reunite the Duchy. |
| Conrad II | | 1250 | 1275-1294 | 24 June or 21 December 1294 | Czersk | Hedwig of Legnica 1265/70 one child | Released after two years of captivity. In 1275 divided the land with his brother Bolesław. After the division of the duchy he received Czersk. His death without male heirs allowed his brother to reunite the Duchy. |
| Boleslaus II | | 1253/8 | 1275-1294 | 20 April 1313 | Płock | Gaudemantė Sophia of Lithuania 1279 three children Kunigunde of Bohemia 1291 (divorced 1302) two children | Reunited the duchy after the death of his brother, but after his own death Masovia was divided again. |
| Boleslaus II | | 1253/8 | 1294-1313 | 20 April 1313 | Masovia | Gaudemantė Sophia of Lithuania 1279 three children Kunigunde of Bohemia 1291 (divorced 1302) two children | Reunited the duchy after the death of his brother, but after his own death Masovia was divided again. |
| Trojden I | | 1284/6 | 1310-1341 | 13 March 1341 | Warsaw | Maria Yurievna of Galicia-Volhynia 1309/10 four children | Son of Boleslaus II, retained Czersk during his father's lifetime. After Boleslaus' death, Trojden received more lands in inheritance and made Warsaw his new capital. Put his own son in the throne of Galicia-Volhynia. |
| Siemowit II | | 1283 | 1313-1345 | 18 February 1345 | Rawa | Unmarried | Son of Boleslaus II, retained Rawa. Left no descendants and his duchy was inherited by his nephews Siemowit III and Casimir I. |
| Wenceslaus I | | 1293/7 | 1313-1336 | 23 May 1336 | Płock | Dannila Elisabeth of Lithuania 1316 two children | Son of Boleslaus II, retained Płock. |
| Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Regencies of Siemowit II, Duke of Rawa and Trojden I, Duke of Warsaw (1336-1340) | Son of Wenceslaus. In 1351 Płock was annexed by the Kingdom of Poland. |
| Boleslaus III | | 1322/30 | 1336-1351 | 20 August 1351 | Płock | Unmarried | Son of Wenceslaus. In 1351 Płock was annexed by the Kingdom of Poland. |
| Annexation to the Kingdom of Poland (1351-1370) ||||||||
| Casimir I | | 1329/31 | 1341-1349 | 26 November/5 December 1355 | Warsaw | Unmarried | Sons of Trojden I, ruled jointly. In 1345 inherited Rawa. In 1349 divided the land between them: Siemowit received Warsaw and Casimir Rawa. After Casimir's death without descendants in 1355, Siemowit reunited Masovia. He also brought Płock from Poland in 1370. After his death the duchy was again divided between his sons Janusz I and Siemowit IV. |
| Casimir I | | 1329/31 | 1345-1355 | 26 November/5 December 1355 | Rawa | Unmarried | Sons of Trojden I, ruled jointly. In 1345 inherited Rawa. In 1349 divided the land between them: Siemowit received Warsaw and Casimir Rawa. After Casimir's death without descendants in 1355, Siemowit reunited Masovia. He also brought Płock from Poland in 1370. After his death the duchy was again divided between his sons Janusz I and Siemowit IV. |
| Siemowit III | | 1320 | 1341-1355 | 16 June 1381 | Warsaw | Euphemia of Opava 1335 five children Anna of Ziębice c.1360 three children | Sons of Trojden I, ruled jointly. In 1345 inherited Rawa. In 1349 divided the land between them: Siemowit received Warsaw and Casimir Rawa. After Casimir's death without descendants in 1355, Siemowit reunited Masovia. He also brought Płock from Poland in 1370. After his death the duchy was again divided between his sons Janusz I and Siemowit IV. |
| Siemowit III | | 1320 | 1345-1349 | 16 June 1381 | Rawa | Euphemia of Opava 1335 five children Anna of Ziębice c.1360 three children | Sons of Trojden I, ruled jointly. In 1345 inherited Rawa. In 1349 divided the land between them: Siemowit received Warsaw and Casimir Rawa. After Casimir's death without descendants in 1355, Siemowit reunited Masovia. He also brought Płock from Poland in 1370. After his death the duchy was again divided between his sons Janusz I and Siemowit IV. |
| Siemowit III | | 1320 | 1355-1381 | 16 June 1381 | Masovia | Euphemia of Opava 1335 five children Anna of Ziębice c.1360 three children | Sons of Trojden I, ruled jointly. In 1345 inherited Rawa. In 1349 divided the land between them: Siemowit received Warsaw and Casimir Rawa. After Casimir's death without descendants in 1355, Siemowit reunited Masovia. He also brought Płock from Poland in 1370. After his death the duchy was again divided between his sons Janusz I and Siemowit IV. |
| John I the Elder | | 1347/52 | 1381-1429 | 8 December 1429 | Warsaw | Danutė Anna of Lithuania 1371/3 four children | Son of Siemowit III, since 1386 hereditary vassal of Poland, after 1391 Duke of Podlasie. Although the division, the duchy of Czersk remained annexed to the duchy of Warsaw. |
| Siemowit IV the Younger | | 1353/6 | 1381-1426 | 21 January 1426 | Płock (with Rawa) | Alexandra of Lithuania 1387 thirteen children | Son of Siemowit III. Since 1386, was an hereditary vassal of Poland, and, although having lost much of his domain to the Teutonic Order in 1382 (Wizna, Zawkrze, Płońsk), he gained other duchies (Bełz) from Poland. |
| Trojden II | | 1403/6 | 1426-1427 | 25 July 1427 | Płock (with Rawa) | Unmarried | Sons of Siemowit IV, ruled jointly. In 1434 the three surviving brothers divided the land: Siemowit received Rawa, Casimir received Bełz, ad Ladislaus received Płock. The death of Siemowit and Casimir in 1442, both without descendants, allowed Ladislaus to reunite the inheritance of his father (all but Gostynin, town that remained under Siemowit V's widow's control). |
| Siemowit V | | 1389 | 1426-1442 | 17 February 1442 | Rawa (since 1434) | Margareta of Opava-Ráciborz bet. 15 October 1434 and 17 February 1437 one child | Sons of Siemowit IV, ruled jointly. In 1434 the three surviving brothers divided the land: Siemowit received Rawa, Casimir received Bełz, ad Ladislaus received Płock. The death of Siemowit and Casimir in 1442, both without descendants, allowed Ladislaus to reunite the inheritance of his father (all but Gostynin, town that remained under Siemowit V's widow's control). |
| Casimir II | | 1401/3 | 1426-1442 | 15 September 1442 | Bełz (since 1434) | Margareta Szamotuły 26 June 1442 no children | Sons of Siemowit IV, ruled jointly. In 1434 the three surviving brothers divided the land: Siemowit received Rawa, Casimir received Bełz, ad Ladislaus received Płock. The death of Siemowit and Casimir in 1442, both without descendants, allowed Ladislaus to reunite the inheritance of his father (all but Gostynin, town that remained under Siemowit V's widow's control). |
| Ladislaus I | | 1406/9 | 1426-1455 | 11/12 December 1455 | Płock | Anna of Oleśnica 1444 two children | Sons of Siemowit IV, ruled jointly. In 1434 the three surviving brothers divided the land: Siemowit received Rawa, Casimir received Bełz, ad Ladislaus received Płock. The death of Siemowit and Casimir in 1442, both without descendants, allowed Ladislaus to reunite the inheritance of his father (all but Gostynin, town that remained under Siemowit V's widow's control). |
| Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | Regency of Anna of Lithuania (1429-1436) | |
| Boleslaus IV | | 1421 | 1429-1454 | 10 September 1454 | Warsaw | Barbara Olelkovna of Slutsk-Kapy 1440/5 ten children | |
| Margareta of Opava-Ráciborz | | 1410 | 1442-1459 | 5 July 1459 | Rawa (at Gostynin) | Siemowit V bet. 15 October 1434 and 17 February 1437 one child | Received Gostynin as her husband's inheritance. After her death her part rejoined Płock. |
| Anna of Oleśnica | | c.1425 | 1455-1482 | After 15 August 1482 | Płock (in Sochaczew (1455-76); in Koło-Mszczonów (1476-82)) | Ladislaus I 1444 two children | Sons of Ladislaus I, ruled jointly. In 1459 inherited Gostynin from their aunt Margareta. After their deaths, Masovia was again reunited by the sons of Boleslaus IV. Their mother Anna, besides the regency of her sons, had also an independent seat in Sochaczew (1455–76). When this land was annexed to Poland, she received Koło and Mszczonów as compensation (1476–82). |
| Sons of Ladislaus I, ruled jointly. In 1459 inherited Gostynin from their aunt Margareta. After their deaths, Masovia was again reunited by the sons of Boleslaus IV. Their mother Anna, besides the regency of her sons, had also an independent seat in Sochaczew (1455–76). When this land was annexed to Poland, she received Koło and Mszczonów as compensation (1476–82). |||||||
| Siemowit VI | | 2 January 1446 | 1455-1462 | 31 December 1461/1 January 1462 | Płock | Unmarried | Sons of Ladislaus I, ruled jointly. In 1459 inherited Gostynin from their aunt Margareta. After their deaths, Masovia was again reunited by the sons of Boleslaus IV. Their mother Anna, besides the regency of her sons, had also an independent seat in Sochaczew (1455–76). When this land was annexed to Poland, she received Koło and Mszczonów as compensation (1476–82). |
| Ladislaus II | | After 31 October 1448 | 1455-1462 | 27 February 1462 | Płock | Unmarried | Sons of Ladislaus I, ruled jointly. In 1459 inherited Gostynin from their aunt Margareta. After their deaths, Masovia was again reunited by the sons of Boleslaus IV. Their mother Anna, besides the regency of her sons, had also an independent seat in Sochaczew (1455–76). When this land was annexed to Poland, she received Koło and Mszczonów as compensation (1476–82). |
| Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Regencies of Barbara Olelkovna of Slutsk-Kapy and Paul Giżycki, Bishop of Płock (1454-1462) | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Casimir III | | 10 June 1448/8 June 1449 | 1454-1471 | 9 June 1480 | Warsaw | Unmarried | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Casimir III | | 10 June 1448/8 June 1449 | 1471-1475 | 9 June 1480 | Płock | Unmarried | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Boleslaus V | | c.1453 | 1454-1488 | 27 April 1488 | Warsaw | Anna Radzanów 20 July 1477 (morganatic, annulled 1480) no children | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| John II | | 1455 | 1454-1471 | 16 February 1495 | Warsaw | Unmarried | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| John II | | 1455 | 1475-1495 | 16 February 1495 | Płock | Unmarried | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Conrad III the Red | | 1447/8 | 1454-1471 1488-1495 | 28 October 1503 | Warsaw | Magdaena Stawrot 1468/70 (morganatic) no children Unknown bef. 20 July 1477 (morganatic, divorced 1493?) no children Anna Radziwiłł bet. 29 September 1496 and 2 April 1497 four children | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Conrad III the Red | | 1447/8 | 1471-1495 | 28 October 1503 | Czersk | Magdaena Stawrot 1468/70 (morganatic) no children Unknown bef. 20 July 1477 (morganatic, divorced 1493?) no children Anna Radziwiłł bet. 29 September 1496 and 2 April 1497 four children | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Conrad III the Red | | 1447/8 | 1495-1503 | 28 October 1503 | Masovia | Magdaena Stawrot 1468/70 (morganatic) no children Unknown bef. 20 July 1477 (morganatic, divorced 1493?) no children Anna Radziwiłł bet. 29 September 1496 and 2 April 1497 four children | Sons of Boleslaus IV, ruled jointly under regency. In 1462 they inherited the rest of Masovia, reuniting the Duchy. However in 1471 they made new partitions: Casimir received Płock, however in 1475 abdicated of his lands to his brother Janusz, who hadn't any share of the land since 1471; Conrad received Czersk and Boleslaus Warsaw, which was reunited with Czersk by Conrad after Boleslaus' death in 1488. In 1495, as the last surviving brother in power, he reunited all Masovia definitely. |
| Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Regency of Anna Radziwiłł (1503-1518) | Sons of Conrad III, ruled jointly. |
| John III | | 27 September 1502 | 1503-1526 | 9/10 March 1526 | Masovia | Unmarried | Sons of Conrad III, ruled jointly. |
| Stanisław I | | 17 May 1501 | 1503-1524 | 8 August 1524 | Masovia | Unmarried | Sons of Conrad III, ruled jointly. |
| Anna | | c.1498 | 1526-1537 | After 26 January 1557 | Masovia | Stanisław Odrowąż 1536 one child | The last Masovian Piast. Sister of Stanislaus and John III. Anna was elected duchess by the nobles to maintain the independence of the Duchy. She forfeited her rights to Poland in 1537. |
