Schools Relations with: An antipope (Latin: antipapa) is a person who claims to be Bishop of Rome and leader of the Roman Catholic Church in opposition to the legitimately elected pope.
Eusebius quotes[5] from an unnamed earlier writer the story of Natalius, a 3rd-century priest who accepted the bishopric of the Adoptionists,[6] a heretical group in Rome.
Afterwards, Pope Martin V was elected and was accepted everywhere except in the small and rapidly diminishing area of influence of Benedict XIII.
The list of popes and antipopes in the Annuario Pontificio attaches the following note to the name of Pope Leo VIII (963–965): At this point, as again in the mid-11th century, we come across elections in which problems of harmonising historical criteria and those of theology and canon law make it impossible to decide clearly which side possessed the legitimacy whose factual existence guarantees the unbroken lawful succession of the successors of Saint Peter.
[10]Thus, because of the obscurities about mid-11th-century canon law and the historical facts, the Annuario Pontificio lists Sylvester III as a pope, without thereby expressing a judgement on his legitimacy.
[12] As Celestine II resigned before being consecrated and enthroned in order to avoid a schism, Oxford's A Dictionary of Popes (2010) considers he "...is classified, unfairly, as an antipope",[13] an opinion historian Salvador Miranda also shares.
Examples include Palmarians, Apostles of Infinite Love Antipopes, and an unknown number of many other Sedevacantist claimants.