| Casimir II the Just | |
|---|---|
 | |
| High Duke of Poland | |
| Tenure | 1177–1191 1191–1194 |
| Predecessor | Mieszko III |
| Successor | Leszek the White |
| Duke of Masovia | |
| Tenure | 1186–1194 |
| Predecessor | Leszek |
| Successor | Leszek I the White |
| Born | 28 October 1138 |
| Died | 5 May 1194 (aged 55) Kraków |
| Burial | Wawel Cathedral, Kraków |
| Spouse | Helena of Znojmo |
| Issue more... | Adelaide Leszek I the White Konrad I of Masovia |
| House | Piast dynasty |
| Father | Bolesław III Wrymouth |
| Mother | Salomea of Berg |
| Religion | Roman Catholic |
Casimir II the Just (Polish: Kazimierz II Sprawiedliwy; 28 October 1138 – 5 May 1194) was a Lesser Polish Duke of Wiślica from 1166 to 1173, and of Sandomierz after 1173. He became ruler over the Polish Seniorate Province at Kraków and thereby High Duke of Poland in 1177; a position he held until his death, though interrupted once by his elder brother and predecessor Mieszko III. In 1186 Casimir also inherited the Duchy of Masovia from his nephew Leszek, becoming the progenitor of the Masovian branch of the royal Piast dynasty, and great-grandfather of the later Polish king Władysław I the Elbow-high. The honorific title "the Just" was not contemporary and first appeared in the 16th century.