John Frederick, Elector of Saxony
Johann Friedrich I, Elector of Saxony (30 June 1503-3 March 1554) was head of the Protestant Confederation of Germany (the Schmalkaldic League), "Champion of the Reformation", and the son of Johann "the Constant" of Saxony (1468-1532).
In 1526 he married Sybilla of Cleves (1512-1554), daughter of Johann III of Cleves (1490-1538) and his wife, Maria of Juelich and Berg (1491-1543), in her turn daughter of Johann Wilhelm of Jülich and Berg (1530-1573).