What are your thoughts on the four antipopes that followed St. Clement III? The first two are just as Orthodox in my opinion, though the last two have problems.
Theodoric was an antipope in 1100 and 1101, in the schism that began with Wibert of Ravenna in 1080, in opposition to the excesses of Pope Gregory VII and in support of the Emperor Henry IV. The earliest record of Theodoric is his signature on a document of the antipope Clement III (Wibert) dated 4 November 1084, where he signs as cardinal deacon of S. Maria in Via Lata. In a letter of 29 July 1099, Clement III refers to Theoderic as one of those cardinals who anathematized Gregory VII (who died on 25 May 1085) as a heretic and simoniac. According to the "Annales Romani", the followers of Clement met secretly in Rome, at night, in St. Peter's Basilica, where they elected and enthroned Cardinal Theodoric, the Bishop of Albano, who may have assumed the name Sylvester III. But he did not dare to remain in the city. Forced to abandon Rome to seek protection of the emperor, Theodoric was seized by partisans of Pope Paschal II, and sent to Rome. He was convicted by judgment of the fathers, and immediately sent to the monastery of Santissima Trinità di Cava, near Salerno, where he was compelled to become a monk. He died at Cava in 1102, according to the epitaph in the crypt of the monastery. A later memorial plaque in La Cava commemorates him under the pontifical name of "Sylvester III"
Adalbert (or Albert) was elected pope of the Catholic Church in February 1101 and served for 105 days. He was a candidate of the Roman party opposed to Pope Paschal II and is regarded today as an antipope. Prior to his election he was created a cardinal by the antipope Clement III. Adalbert's first public appearance drew a large crowd and rapidly degenerated into unrest. The situation eventually got so bad that he was forced to take refuge in the basilica of San Marcello al Corso under the protection of Romano and Giovanni Oddoline. Many clergy who tried to reach the church were beaten and stripped naked by the mob. Paschal II then bribed Giovanni to hand the antipope over. Adalbert was stripped of his pallium and handed over to Paschal's forces. His pontificate had lasted 105 days. He was led behind a horse (as a sign of contempt) to the Lateran Palace, where Paschal was residing. He was then imprisoned in a tower. The Annales Romani and the biography of Paschal in the Liber pontificalis agree that the acceptance of the bribe and the antipope's imprisonment took place in the space of one day. Adalbert was eventually sent to the Benedictine monastery of San Lorenzo in Aversa, where he spent the rest of his life. The date of his death and the place of burial are not known.
Sylvester IV, born Maginulf, was a claimant to the Papacy from 1105 to 1111 in opposition to Paschal II. A priest before his election, he was probably a native of Rome. Though he had no connections to the previous followers of Clement III, He did have the backing of the Roman militia and initially of the Holy Roman Emperor Henry IV. Henry later used him as a pawn in his negotiations with Paschal. Henry, who wanted Paschal to crown him emperor, forced Sylvester to renounce the Papacy on 12 or 13 April 1111.
Gregory VIII (died 1137), born Mauritius Burdinus (Maurice Bourdin), was antipope from 10 March 1118 until 22 April 1121. He was born in the Limousin, part of Occitania, France. He was educated at Cluny, at Limoges, and in Castile, where he was a deacon at Toledo. In 1098/1099 his Cluniac connections recommended him as Bishop of Coimbra. After a four-year pilgrimage to the Holy Land, he was made Archbishop of Braga in 1109. There he was one of the principal agents of the Burgundian Henry, Count of Portugal, in his reorganization of the Portuguese church. Portugal was then a fief of León, and the ambitious Count Henry pursued a vigorous program of ecclesiastical and political autonomy. By 1114, Mauritius had become embroiled in a dispute with the Spanish primate and papal legate in Castile, Bernard of Toledo, to the extent that he was called to Rome and suspended by Pope Paschal II (1099–1118). Nevertheless, he found favor at the papal court, and in 1116, when Emperor Henry V (1105–1125) invaded Italy during the ongoing confrontations over the Emperor's rights of investiture of clerics, Paschal II sent Mauritius with some cardinals on an embassy to the emperor, while the Pope and the Curia fled south to Benevento. Mauritius openly espoused the cause of Henry, and defected to the Emperor's side. Henry V went to Rome, and on Easter Sunday, March 23, 1117, was crowned Holy Roman Emperor by Mauritius. Paschal II deposed and excommunicated Henry V and removed Mauritius from office. In March 1118 three cardinals created by Antipope Clement III (1080/84-1100) joined his obedience and formed his own Sacred College:
Romanus — cardinal-priest of San Marco and provost of the titular church of San Marcello
Cinthius — cardinal-priest of San Crisogono
Teuzo — cardinal-priest, former legate of Clement III in Hungary
When Paschal II died on 24 January 1118, he was succeeded by Pope Gelasius II (1118–19). Henry V went to Rome but Gelasius II escaped to Gaeta and refused to meet the Emperor to discuss German affairs. Partly in reprisal the imperial party among the cardinals then annulled Gelasius II's election, and on March 1, 1118 Mauritius was proclaimed Pope, taking the name Gregory VIII. Gelasius II, at Capua, proceeded to excommunicate both Gregory VIII and Henry V on April 7, 1118. After Gelasius II's death, when Calixtus II had been elected Pope in 1119, Henry V was induced to change papal allegiance, in the Concordat of Worms of 1122. Calixtus II entered Rome, and Gregory VIII left, going to Sutri, where he was in April 1121, when papal troops of Calixtus II closed up the city for eight days until its citizens surrendered antipope Gregory VIII. He was taken to Rome and imprisoned in the Septizonium. After having been moved in confinement from monastery to monastery, he finally died at La Cava, Salerno, some time after August 1137.