John of the Lithuanian Dukes was Bishop of Vilnius (1519–36) and of Bishop of Poznań (1536–38). He was the bishop when Protestantism was making the first inroads into the Grand Duchy of Lithuania and took the first steps in combating it. John was an illegitimate son of Sigismund I the Old, King of Poland and Grand Duke of Lithuania, and his mistress Katarzyna Telniczanka.
- Occupation
- canon, cantor, Catholic priest, Catholic bishop
- Position held
- king's secretary at the Polish court, Roman Catholic Bishop of Poznań, Roman Catholic bishop of Vilnius
- Citizenship
- Grand Duchy of Lithuania, Kingdom of Poland
- Born
- January 8, 1499, 1498
