Сигизмунд Кейстутович
The Jagiellonians were the primary inheritors of the title of the Grand Duke of Lithuania following the deaths of Vytautas the Great, Sigismund Kęstutaitis (children of Grand Duke Kęstutis) as they remained as the most powerful branch of the Lithuanian Gediminids dynasty and were direct ancestors of Grand Duke Gediminas by the man's line.