Frederick III or Frederick the Wise, 1463-1525, elector of Saxony (1486-1525). At Wittenberg he founded (1502) the university where Martin Luther and Melanchthon taught. At a crucial period for the early Reformation, Frederick protected Luther from the pope and the emperor, and took him into custody at the Wartburg castle after the Diet of Worms (1521), which put Luther under the imperial ban. Frederick, however, had little personal contact with Luther and remained a Catholic, although he gradually inclined toward the doctrines of the Reformation.