One who uncanonically claims or exercises the office of Roman pontiff. Historically this situation has occurred as the result of various causes, not all of which imply bad faith. Antipopes have risen by violent usurpation (Constantine II, 767); by election following a prior selection falsely judged as invalid (Clement VII, 1378); accession after an unwarranted deposition or deportation of the previous pope (Felix II, 355); or double election (Anacletus II, Innocent II, 1130). Yet not all antipopes emerged because of malfeasance or bad faith. Because of the lack of a readily accessible electoral code, there could be confusion as to the requirements for a valid choice. Instances occurred where a pontificate, uncanonical in its beginnings, was validated by subsequent acceptance on the part of the electors (Vigilius, after Silverius's resignation or death, 537). It must be frankly admitted that bias or deficiencies in the sources make it impossible to determine in certain cases whether the claimants were popes or antipopes.
The term "antipope" can be traced to c. 1192 [J. H. Baxter and C. Johnson, Medieval Latin Word-List (1950) 22], although other names appear earlier, e.g., perturbator (370; Corpus scriptorum ecclesiasticorum latinorum 35:52), pervasor (506; Thiel, Epist. Rom. pont. 1:697). Authors variously calculate the number of antipopes: Baümer counts 33 with three others bracketed with legitimate popes: Amanieu, 34; Frutaz, 36 plus seven doubtful and nine improperly designated; Moroni, 39. Since 1947 the Vatican Annuario Pontificio has printed Mercati's list of popes that includes 37 antipopes in the text. All lists are subject to reservations, and the Mercati catalogue has provoked dissent. Biographies of the 37 antipopes can be found in this encyclopedia under their pontifical names, except for Anastasius the Librarian, who can be found under that name.
Bibliography: Annuario Pontificio (2001) 7*–22*, cf. a. mercati, "The New List of the Popes," Mediaeval Studies 9 (1947) 71–80. l. duchesne, Liber pontificalis (Paris 1886–92; 1958). p. jaffÉ, Regista pontificum romanorum ab condita ecclesia ad annum post Christum natum 1198 (2d ed. Leipzig 1881–88; repr. 1956). l. a. anastasio, Istoria degli antipapi, 2 v. (Naples 1754). g. moroni, Dizionario de erudizione storico-ecclesiastica (Venice 1840–61) 2:181–215. a. amanieu, Dictionnaire de droit canonique ((Paris 1935–65) 1:598–622. g. jacquemet, Catholicisme 1:653–658. Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner (Freiberg 1957–65) 4:583–585. r. bÄumer, ibid. 8:54–59.
[h. g. j. beck/eds.]