Why Famous: Best remembered for granting indulgences for those who donated to reconstruct St. Peter's Basilica, which practice was challenged by Martin Luther's 95 Theses. Did not take seriously the array of demands for church reform that would quickly grow into the Protestant Reformation.
- 1513-03-11 Giovanni de' Medici chosen Pope Leo X
- 1514-01-14 Pope Leo X issues a papal bull against slavery.
- 1515-09-13 -14] Battle at Marignano: France beats Habsburgers & Pope Leo X
- 1517-03-16 Pope Leo X signs 5th Council of Lateranen
- 1521-01-03 Martin Luther excommunicated by Pope Leo X from the Roman Catholic Church
- 1521-05-28 Pope Leo X signs treaty with Holy Roman Emperor Charles V
- 1521-10-11 Pope Leo X titles King Henry VIII of England "Defender of the Faith"