Manvydas (also: Mantvydas, Polish: Monwid; * to 1288, † probably on February 2, 1348 ) was, according to tradition, the eldest son of the Lithuanian Grand Duke Gediminas († 1341 ) and the progenitor of the eponymous noble family of Manvydai. About his life hardly assured facts are known, but it seems certain that he inherited after the death of his father Kernavė and Slonim. He probably died along with his brother Narimantas in the Battle of the Strėva, which ended with a heavy Lithuanian defeat against the army of the Teutonic Order.