Casimir II the Just, Polish son of Bolesław III Wrymouth (b. 1138)
Casimir II the Just (Polish: Kazimierz II Sprawiedliwy; 28 October 1138 – 5 May 1194) was a Lesser Polish Duke of Wiślica from 1166–1173, 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 the Old. 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.