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.

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

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

Pope Alexander VI excommunicates Girolamo Savonarola.

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

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

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.