Lambert Mieszkowic (c. 981 – after 992/95), was a Polish prince member of the House of Piast.
Nothing is known about his first years of life. Lambert's first appearance was in the document called "Dagome iudex" (ca. 991–92), alongside with his parents and brother Mieszko. After Mieszko I's death (25 May 992) began the war between Bolesław I and his half-brothers for the paternal heritage, who, according to some historians lasted only a few weeks, and by others, only finished in 995. Despite the tensions between both parties, Bolesław I's first son with Emnilda of Lusatia was probably named after him; it's expected that the choice of this name for his son was an expression of warming relations between Bolesław I and his stepmother Oda.
At the end, Bolesław I took control over all the country and expelled his stepmother and half-brothers from Poland to Germany. Lambert's further fate is unknown; previously he was identified with Lambert, Bishop of Kraków (d. 1030), but now this identification is contested.
In 1032 certain Dytryk (son of either Lambert or his brother Mieszko) returned of Poland and took control over part of the country after the fall of Mieszko II Lambert, but his reign was short-lived: in 1033 he was deposed and expelled by Mieszko II, who reunited all Poland under his hands.
- K. Jasiński, Rodowód pierwszych Piastów, p. 114.
- K. Jasiński, Rodowód pierwszych Piastów, p. 105; but see G. Labuda: Mieszko II, Poznań 2008, p. 171-172.
- Thietmari chronicon (edited by Marian Zygmunt Jedlicki), Poznań 1953, p. 224.
- B. Kürbisówna, Dagome iudex – studium krytyczne, [in:] Początki Państwa Polskiego, Poznań 1962, vol. I, p. 396.
- O. Balzer, Genealogia Piastów, Kraków 1895.
- K. Jasiński, Rodowód pierwszych Piastów, Wrocław-Warsaw 1992.
- G. Labuda, Mieszko I, Wrocław 2002, p. 154, 178, 188, 193, 195, 199, 268.
- J. Widajewicz, Początki Polski, Wrocław 1948.