When did the cousin of the Grand Duke of Lithuania die?
Vytautas Vytautas (c. 1350 – October 27, 1430), also known as Vytautas the Great (Lithuanian: "   ", Belarusian: "Вітаўт Кейстутавіч (Vitaŭt Kiejstutavič)" , Polish: "Witold Kiejstutowicz" , Rusyn: "Vitovt", Latin: "Alexander Vitoldus") from the 15th century onwards, was a ruler of the Grand Duchy of Lithuania, which chiefly encompassed the Lithuanians and Ruthenians. He was also the Prince of Hrodna (1370–1382), Prince of Lutsk (1387~1389), and the postulated king of the Hussites.
Michał Kazimierz Radziwiłł Prince Michał Kazimierz Radziwiłł (Lithuanian: "Mykolas Kazimieras Radvila" ) (26 October 1625 – 14 November 1680) was a Polish–Lithuanian noble and magnate. He is sometimes referred to as "the first" Michał Kazimierz Radziwiłł, to distinguish him from the other member of his family to use the name.