Calixtus II
Calixtus II, Callixtus II, or Callistus II, d. 1124, pope (1119–24), named Guy of Burgundy, successor of Gelasius II. The son of count William I of Burgundy, he was archbishop of Vienne during the investiture controversy with Holy Roman Emperor Henry V. When Gelasius died while in exile in France, Calixtus was consecrated pope at Vienne. He immediately summoned a large council at Reims (1119) that proceeded to anathematize the emperor and the antipope that Henry had installed (1118), Gregory VIII. Public reaction sided with the pope and the antipope was imprisoned. Henry thereupon agreed to sign (1122) the famous Concordat (see Worms, Concordat of), a compromise that recognized the rights of the church in selecting its leadership. Thus was the investiture controversy ended and the reform program of Gregory VII realized. Calixtus then called to Rome (1123) a great council in Western Europe (see Lateran Council, First) to ratify the achievements of Pope Gregory VII. He was succeeded by Honorius II.