Leo X, 1475–1521, pope (1513–21), a Florentine named Giovanni de' Medici; successor of Julius II. He was the son of Lorenzo de' Medici, was made a cardinal in his boyhood, and was head of his family before he was 30 (see Medici). Leo was not a competent ruler; he was a good, pious man, a dilettante of letters and art, but not greatly interested in the advancement of the church. His chief fame rests on his patronage of Raphael, on the continuation of St. Peter's by Bramante, and on his literary circle, including Cardinals Bembo and Bibbiena and many others. The Fifth Lateran Council, called with the hope that it would effect reforms, achieved little. The Protestant Reformation began when Martin Luther posted (1517) his famous theses against the sale of indulgences, an activity practiced by Leo to provide income for his building program. Leo excommunicated the reformers, notably with the bull Exsurge Domine (1520), but he failed to deal effectively with the trouble. In politics he brought the papacy temporary hegemony in Italy by dexterity in diplomatic maneuvers. Leo granted Henry VIII of England the title Defender of the Faith ( Defensor Fidei ). He was succeeded by Adrian VI.