Silly images you find on the internet!
From the interview granted by Cardinal Kasper, the oldest elector in the college, to Italian secularist daily La Repubblica, published today (print edition, p. 16):
Your Eminence, what will you say to Benedict XVI when, following the end of the conclave, you go meet him?
"So many things. The first one is a recommendation. I will suggest to him to not let himself be used by anybody. The risk is too great that the government of the Church receive his influence. He made a specific choice, that supposed a step back. He, therefore, ought to be discreet. Avoid mingling with the problems related to the government of the Church. Then I will speak amicably with him of what pleases us both, theology."
My comment: There could be a very real possibility (although I sincerely believe we will not again hear from the "Pontifex Maximus Emeritus" given the nature of his personality and the love he has for the Church) that we could enter into a period of the Church of competing popes and where one is declared eventually the "anti-pope."
But in the 2000 year history of the Catholic Church, there have been more than 40 antipopes. Anantipope is a bishop who claims to be the pope, but was not canonically elected as Bishop of Rome (i.e., supreme pontiff).
The term anti-pope refers to any person who claims to be pope, but whose claim is treated as invalid today by the Roman Catholic Church. This should be a straightforward concept, but in practice it is much more difficult and complex than it might appear.
The problems lie in determining who qualifies as pope and why. It isn't enough to say that their election did not follow standard procedures, because those procedures have changed over time. Sometimes the rules aren’t even followed. Innocent II was elected in secret by a minority of cardinals but his papacy is treated as legitimate. It isn't enough to say that an alleged pope did not lead an adequately moral life because many legitimate popes led terrible lives while the first anti pope, Hippolytus, is a saint.
Over time names have shifted back and forth between the lists of popes and anti-popes because people have changed their minds about what to do with them. The Vatican’s official list of popes is called the Annuario Pontificio and even today there remain four instances where it isn’t absolutely clear on whether someone was a legitimate successor of Peter.
Here is a [purported] list of the 42 antipopes that the Church had to contend with before Vatican II:
1. St. Hippolytus (reconciled with Pope St. Pontian and died as martyr to the church),217–235
2. Novatian, 251–258
3. Felix II (confused with a martyr with the same name and thus considered an authentic-pope until recently), 355–365
4. Ursicinus (Ursinus), 366–367
5. Eulalius, 418–419
6. Laurentius, 498–499, 501–506
7. Dioscorus (legitimate perhaps as opposed to Boniface II but died 22 days after election), 530
8. Theodore (II) (opposed to antipope Paschal), 687
9. Paschal (I) (opposed to antipope Theodore), 687
10. Theofylact, 757
11. Constantine II, 767–768
12. Philip (replaced antipope Constantine II briefly; reigned for a day and then returned
to his monastery), 768
13. John VIII, 844
14. Anastasius III Bibliothecarius, 855
15. Christopher, 903–904
16. Boniface VII, 974, 984–985
17. John Filagatto (John XVI), 997–9
18. Gregory VI, 1012
19. Sylvester III, 1045
20. John Mincius (Benedict X), 1058–1059
21. Pietro Cadalus (Honorius II), 1061–1064
22. Guibert of Ravenna (Clement III), 1080 & 1084–1100
23. Theodoric, 1100–1101
24. Adalbert, 1101
25. Maginulf (Sylvester IV), 1105–1111
26. Maurice Burdanus (Gregory VIII), 1118–1121
27. Thebaldus Buccapecuc (Celestine II) (legitimate but submitted to opposing pope,Honorius II, and afterwards considered an antipope), 1124
28. Pietro Pierleoni (Anacletus II), 1130–1138
29. Gregorio Conti (Victor IV), 1138
30. Ottavio di Montecelio (Victor IV), 1159–1164
31. Guido di Crema (Paschal III), 1164–1168
32. Giovanni of Struma(Callixtus III), 1168–1178
33. Lanzo of Sezza (Innocent III), 1179–1180
34. Pietro Rainalducci (Nicholas V), antipope in Rome, 1328–1330
35. Robert of Geneva (Clement VII), antipope of the Avignon line, 20 September 1378 – 16 September 1394
36. Pedro de Luna (Benedict XIII), anti-pope of the Avignon line, 1394–1423
37. Pietro Philarghi Alexander V, antipope of the Pisan line, 1409–1410
38. Baldassare Cossa (John XXIII), anti-pope of the Pisan line, 1410–1415
39. Gil Sánchez Muñoz (Clement VIII), anti-pope of the Avignon line, 1423–1429
40. Bernard Garnier (the first Benedict XIV), antipope of the Avignon line, 1425–c. 1429
41. Jean Carrier (the second Benedict XIV), antipope of the Avignon line, 1430–1437
42. Duke Amadeus VIII of Savoy (Felix V), 5 November 1439 – 7 April 1449
One of the most notorious cases in Church history was that of the Anti-pope Anacletus II, who reigned in Rome from 1130 to 1138. Anacletus had been implanted in an uncanonical election after Innocent II, the true pope, had already been chosen. Despite his invalid and uncanonical election, Antipope Anacletus II gained control of Rome and the support of the majority of the College of Cardinals. Anacletus held the support of almost the entire populace of Rome, until the true pope regained control of the city in 1138. (The Catholic Encyclopedia, “Anacletus,” Vol. 1, 1907, p. 447.)
My comment: Who will be the first anti-pope after Vatican II and is the stage set for it? Time will tell!