- Mar 12 Pope Leo IX escapes captivity & returns to Rome
- Jul 4 Brightest known supernova SN 1054 (creates the Crab Nebula) 1st reported by Chinese astronomers
- Jul 16 Beginning of the Great Schism between Western and Eastern churches when Roman Cardinal Humbert issues bull of excommunication against Cerularius, Patriarch of Constantinople, on the altar of the Hagia Sophia, Constantinople
- Jul 20 Patriarch of Constantinople Michael Caerularius, as head of a Synod held in Constantinople excommunicates Cardinal Humbert of the Western church (Rome)
Gregory I
Gregory XIII
Julius II
Julius III
Leo X
Pius V