Pope Gregory XIII

Pope Gregory XIII, who reigned from 1572 to 1585, is best known for reforming the calendar. He established the Gregorian Calendar, which corrected inaccuracies in the Julian Calendar that had been used since Caesar’s time. This reform adjusted the leap year system to better align the calendar with the seasons, ultimately leading to a more accurate way of tracking the year. His calendar is the one most widely used today. Gregory XIII also supported education and the spread of Catholicism through missions, reinforcing the Church's influence during the Counter-Reformation.