Excommunicated by Leo IVAnastasius was considered an excellent scholar, fluent in both Greek and Latin. In 847 Pope Leo IV (847-855) made him cardinal priest of St. Marco's parish. For unknown reasons today, he abandoned his parish not long after, and was thus excommunicated by Leo IV in 850. In 853, not having returned, he was declared anathemised by a Roman synod, and later deposed.
AntipopeAfter cardinal Hadrian turned down his own papal election, the majority of clergy elected Pope Benedict III (855-858) as the new Pope. A delegation was then sent to receive approval from the Holy Roman Emperor, Louis II, as was required. Anastasius' supporters, most likely championed by his uncle Arsenius, bishop of Orta, secretly met with the delagates and bribed them to persuade Louis II that Anastasius was to be pope.
Cousin rapes pope's familyIn 868, his cousin (some sources say brother) named Eleutherius, raped and murdered both the mother and daughter of Pope Adrian II. The murderer was tried and executed, and Anastasius was removed from his chancery and excommunicated once again. The excommunication was later dropped and he was restored.
DignitaryIn 869 he was sent by Louis II as part of a royal delegation to Constantinople to arrange a marriage between Ermengard, the daughter of Louis II, and Leo VI, oldest son of Basil I, the Eastern emperor.
Pope Joan writingsThe earliest known writings concerning the legend of the female Pope Joan (855-858) are contained in a chronicle by Anastasius.
Two different AnastasiusesAccording to some scholars, Anastasius the Antipope was not the same person as Anastasius the Librarian. Other scholars claim they are.
817-876: King of East Francia, Louis (the German)
839-875: King of Italy, Louis II
842-867: Eastern Roman Emperor, Michael III (the Drunkard)
843-877: King of West Francia, Charles (the Bald)
843-855: King of Lotharingia, Lothar I
847-855: Pope Leo IV
855-858: Antipope Joan
855-858: Pope Benedict III
855-869: King of Lotharingia, Lothar II