Vladimir Olgerdovich was a son of which ruler of medieval Lithuania?
Algirdas Algirdas (Belarusian: Альгерд , Russian: Ольгерд , Polish: "Olgierd" ;  1296  – May 1377) was a ruler of medieval Lithuania. He ruled the Lithuanians and Ruthenians from 1345 to 1377. With the help of his brother Kęstutis (who defended the western border of the Duchy) he created an empire stretching from the present Baltic states to the Black Sea and to within fifty miles of Moscow.
Vlad Călugărul Vlad IV Călugărul, (believed born prior to 1425 – September 1495) translated as Vlad the Monk, was the pious half-brother of Vlad III (Vlad the Impaler, or Dracula), and one of many rulers of Wallachia during the 15th century. Vlad the Monk was a contender to his brother's throne as ruler of the principality of Wallachia for many years, but he took no active part in fighting for the throne until near the end of Vlad III's lifetime.