Definition
Ugo Buoncompagni (1502–1585) was Pope Gregory XIII. He was an Italian lawyer and diplomat before becoming pope. He's most famous for implementing the Gregorian calendar in 1582. Gregory XIII aimed to standardize the calendar and correct inaccuracies in the Julian calendar. His papacy coincided with the Counter-Reformation. Ugo Buoncompagni's legal background influenced his approach to papal governance.