1054    Three Roman legates break relations between Western and Eastern Christian Churches through the act of placing an invalidly-issued Papal Bull of Excommunication on the altar of Hagia Sophia during Saturday afternoon divine liturgy. Historians frequently describe the event as the start of the East-West Schism.

1077    Walk to Canossa: The excommunication of Henry IV, Holy Roman Emperor is lifted.

1227    Frederick II, Holy Roman Emperor, is excommunicated by Pope Gregory IX for his failure to participate in the Crusades.

1497    Pope Alexander VI excommunicates Girolamo Savonarola.

1520    Pope Leo X threatens to excommunicate Martin Luther in papal bull ''Exsurge Domine''.

1965    Pope Paul VI and Patriarch Athenagoras simultaneously lift mutual excommunications that had been in place since 1054.

1979    Sonia Johnson is formally excommunicated by The Church of Jesus Christ of Latter-day Saints for her outspoken criticism of the church concerning the proposed Equal Rights Amendment to the Constitution of the United States.