thumb|Kaunas Castle was unsuccessfully defended by Vaidotas
Vaidotas () was a son of Kęstutis, Grand Duke of Lithuania. In reliable historical sources he is mentioned only twice: as defender of Kaunas Castle in 1362 and as ruler of Navahrudak. Due to very limited information, his life is subject to wide-ranging theories by historians.
Historical mentions
According to the chronicles of Wigand of Marburg, he was the commander of the garrison of the newly built Kaunas Castle during the three-week siege in April 1362. After strong resistance the castle was taken over and then destroyed. Vaidotas with 36 men tried to break through, but was taken prisoner.