Henry II the Pious
Leszek was the eldest son of Duke Casimir I of Kuyavia and his second wife, Constance, daughter of Henry II the Pious from the Silesian branch of the Piast dynasty. His nickname, "Black" (Latin: "Niger"), appears for the first time in the 14th century "Kronika Dzierzwy", and was probably given to him for his dark hair.