Kęstutis

Kęstutis (c. 1297–1382), son of Grand Duke Gediminas, was Duke of Trakai and, from 1345, co-ruler with his brother Algirdas, ruling western Lithuania. He spent decades defending Lithuania against the Teutonic Knights, negotiating conversion with the pope and accepting a crown promise from the King of Hungary only to escape.

After Algirdas died in 1377 he seized Vilnius from his nephew Jogaila in 1381 and ruled alone, but Jogaila retook the city in 1382; Kęstutis was captured and died in Kreva Castle. His son by Birutė was Vytautas.