796 (I)
(1) 1. Pasquale Massimi, Roman, monk and abbot of S. Stefano, Rome, cardinal priest of S. Prassede in 796. (1)

(1) Elected Pope Paschal I on January 25, 817. Died between February and May 824. Inscribed in the Roman Martyrology, his feast, on February 11 or May 14, was dropped from the calendar in 1963.

797 (II)
(2) 1. Giovanni, bishop of Porto in 797. + Between 814 and 826. (1)
(3) 2. Gregorio, O.S.B.Fossano, Roman, title of S. Marco in 797. (2)
(4) 3. Sergio, Roman, Can.Reg.Lat., title of Ss. Silvestro e Martino ai Monti in 797. (3)

(1) The diocese of Porto dates back to the third century. Its episcopal series begins after 314. The diocese of Silva Candida or Santa Rufina was united to Porto in 1119. This is its first known cardinal bishop.
(2) Elected Pope Gregory IV in September 827. Died on January 25, 844.
(3) Elected Pope Sergius II on January 25, 844. Died on January 27, 844.

799 (III)
(5) 1. Issa (or Jesse), bishop of Sabina in 799. + Before 804.

803 (IV)
(6) 1. Pietro, bishop of Frascati in 803. His biography in Italian, diocese of Frascati. (1)

(1) The diocese of Frascati (called Tusculum), dates back to at least 269 when its episcopal series starts. This is its first known cardinal bishop. This site says that he was named bihop in 803 o 757?

804 (V)
(7) 1. Bernardo, bishop of Ostia in 804. + 805.
(8) 2. Teodoro, bishop of Sabina in 804. + Before 826.

805 (VI)
(9) 1. Pietro, bishop of Ostia (?) in 805. + Before 826.
(10) 2. Romano, title of S. Pudenziana in 805. + Before 853.

815 (VII)
(11) 1. Stefano, Roman, created cardinal priest or deacon before 815. His title or deaconry is not known. (1)

(1) Elected Pope Stefano IV (V) on June 22, 816. Died January 24, 817.

816 (VIII)
(12) 11. Eugenio Savelli (?), Roman, title of S. Sabina in 816. (1)

(1) Elected Pope Eugenius II between February and May 824. Died in August 827.

Elected pope on June 22, 816. Died January 24, 817. No names of new cardinals are found in his pontificate.

820 (I)
(1) 1. Valentino Leoni, Roman, of the gens Leontia, cardinal deacon in 820, his deaconry is not known. (1)

(1) Elected Pope Valentine in August 827. Died in September 827.

823 (II)
(2) 1. Giovanni, bishop of Silva Candida or Santa Rufina in 823. + 826.

824 (III)
(3) 1. Sisinio (or Zizinio), cardinal priest before 824, his title is not known. + (?) (1)

(1) Elected antipope in February 824 at the same time as Eugenius II, resigned a month later. He is considered Antipope by some authors but is not mentioned in the official list of Roman pontiffs in Annuario Pontificio per l'Anno 2009 (Città del Vaticano : Libreria Editrice Vaticana, 2009).

Unknown date (IV)
(4) 1. Teodoro, called Nomenclator, cardinal priest, his title is not known. + (?).

825 (I)
(1) 1. Giovanni Datus, cardinal deacon of Ss. Sergio e Bacco in 825 (1). + (?).

(1) The deaconry of Ss. Sergio e Bacco, one of the seven original ones, was erected by Pope Agatho in 678 in the VIII Region of Rome, in the Roman Forum, next to the Arch of Septimus Severus. It was suppressed by Pope Sixtus V in 1587 and later demolished during the pontificate of Paul V (1605-1621).

826 (II)
(2) 1. Cesare (or Cesareo), bishop of Ostia in 826. + Before 854.
(3) 2. Gregorio, bishop of Velletri in 826. + Before 853.
(4) 3. Stefano, bishop of Porto in 826. + Before 853.
(5) 4. Costantino, bishop of Palestrina in 826. + (?).
(6) 5. Samuele, bishop of Sabina in 826. + Before 853.
(7) 6. Benedetto, bishop of Albano in 826. + Probably before 844.

827 (III)
(8) 1. Giusto, from Imola, title of S. Cecilia in 827. + Before 853.

Elected pope in August 827. Died in September 827. No names of new cardinals are found in his pontificate.

827 (I)
(1) 1. Luciano, title of S. Eusebio in 827 (?). + Before 853.

829 (II)
(2) 1. Ottavio Elario (or Elarius), from Ardea, title of S. Prassede in 829. + (?).

844 (III)
(3) 1. Lucino (or Luciano), from Foligno, created cardinal deacon of the IX Region of Rome in 844. + (?). (1)

(1) Admitted by Pope Leo IV into the order of cardinal priests. This is the first example of a cardinalitial option.

[Antipope] John was elected by the populace of Rome on January 25, 844. He was a deacon, not a cardinal, and was quickly ejected from the Lateran palace, where his supporters had enthroned him, by Pope Sergius II. He was confined to a monastery and nothing more is known about him. No names of new pseudocardinals are found in his pontificate.

844 (I)
(1) 1. Leone, O.S.B. (or Can.Reg.), Roman, of the monastery of Ss. Silvestro e Martino ai Monti, title of Ss. Quatro Coronati in 844. (1)
(2) 2. Adriano (?), title of S. Marco in 844. + Before 853.
(3) 3. Fortunato Amalario (or Amalarius), cardinal priest in 844 (?), his title is not known. + (?).

(1) Elected Pope Leo IV in January 847. Died July 17, 855. Inscribed in the Roman Martyrology, his feast was celebrated on July 17 and is now suppressed.

846 (II)
(4) 1. Nicola, cardinal deacon in 846 (?), his deaconry is not known. + (?).

847 (I)
(1) 1. N.N., his name is not known, bishop of of Frascati in 847. + (?).

Note. Following is the list given by Chacón-Oldoini, Vitae et res gestae Pontificum Romanorum et S. R. E. Cardinalium, I, col. 625. All of them participated in the Council of Rome of 853.

(853) (II)
(2) 1. Megisto (or Megistus, or Megetius, or Leone?), monk, prior of the monastery of S. Gregorio ad Clivum Scauri, Rome, bishop of Ostia in 854 (?). + Before 868.
(3) 2. Giovanni, bishop of Velletri in 853. + Before 867.
(4) 3. Rodoaldo, bishop of Porto in 853. + (?). (1)
(5) 4. Sergio, bishop of Sabina in 853. + 868 or at least before 879.
(6) 5. Petronacio, bishop of Albano in 853. + ca. 867.
(7) 6. Anastasio il Bibliotecario, created cardinal priest of S. Marcello in 847. + Between 877 and 879. (2)
(8) 7. Romano, title of S. Pudenziana in 853. + (?).
(9) 8. Sergio, title of S. Clemente in 853. + (?).
(10 9. Leone, title of S. Cecilia in 853. + Before 867.
(11) 10. Zaccaria, title of S. Crisogono in 853. + After 867.
(12) 11. Benedetto, seniore, title of S. Maria in Trastevere in 853. (3)
(13) 12. Leone, title of S. Lorenzo in Damaso in 853. + (?).
(14) 13. Paolo, title of S. Balbina in 853. + Before 867.
(15) 14. Leone, title of S. Ciariaco alle Terme in 853. + Before 867.
(16) 15. Adriano, Roman, title of S. Marco in 853. (4)
(17) 16. Giorgio, title of S. Anastasia in 853. + (?).
(18) 17. Romano, title of Ss. Giovanni e Paolo in 853. + Before 872.
(19) 18. Lucino (or Luciano), title of S. Eusebio in 853. + (?). (5)
(20) 19. Gioviniano, title of S. Sabina in 853. + (?).
(21) 20. Adriano, title of Ss. Gervasio e Protasio in 853. + (?).
(22) 21. Giorgio, title of of S. Lorenzo in Lucina in 853. + Before 867.
(23) 22. Giovanni, cardinal priest in 853, his title is not known. + (?).
(24) 23. Leone, title of Ss. Quatro Coronati in 853. + Before 882.
(25) 24. Martino, title of S. Marcello in 853. + (?).
(26) 25. Giovanni, title of S. Prisca in 853. + (?).
(27) 26. Giovanni, cardinal deacon, protodeacon in 853, his deaconry is not known. + (?).
(28) 17. Giovanni, cardinal deacon in 853, his deaconry is not known. + (?).
(29) 28. Nicola, Roman, cardinal deacon in 853, his deaconry is not known. (6)
(30) 29. Benedetto, cardinal deacon in 853, his deaconry is not known. + (?).
(31) 30. Leoncio, cardinal deacon in 853, his deaconry is not known. + (?).
(32) 31. Benedetto, cardinal deacon in 853, his deaconry is not known. + (?).

(1) Deposed and excommunicated in 864 because of simony.
(2) Shortly after having been created cardinal, he abandoned his title, left Rome, sought refuge under Emperor Louis II, intrigued against the pope and refused to return to Rome. He was deposed, anathematized and excommunicated in the Council of Rome on December 16, 850, in Ravenna on May 29, 853 and again in Rome on December 8, 853. At the death of Pope Leo IV, he had himself elected Antipope Anastasius III on September 21, 855. A few days later, he had to leave the place to the legitimate Pope Benedict III, who reduced him to the lay state and confined him to the monastery of S. Maria in Trastevere, Rome. Reconciled with Pope Nicholas I in 858, he became his secretary and legate. Pope Adrian II lifted his suspension as priest and named him Librarian of the Roman Church, hence his nickname Bibliotecario.
(3) Elected Pope Benedict III in July 855. He died on April 17, 858.
(4) Elected Pope Adrian II on December 14, 867. Died in November or December 872.
(5) Annuaire Pontifical Catholique, 1926, p. 152, says that undoubtedly, he is the same as cardinal no. 1 of Pope Gregory IV.
(6) Elected Pope Nicholas I on April 24, 858. Died on September 13, 867. Inscribed in the Roman Martyrology, his feast is on November (September?) 13.

Elected pope in July 855. He died on April 17, 858. No names of new cardinals are found in his pontificate.

Had himself elected Antipope Anastasius III on September 21, 855. A few days later, he had to leave the place to the legitimate Pope Benedict III, who reduced him to the lay state and confined him to the monastery of S. Maria in Trastevere, Rome. Reconciled with Pope Nicholas I in 858. He died between 877 and 879. No names of new pseudocardinals are found in his pontificate.

863 (I)
(1) 1. Leone, bishop of Silva Candida or Santa Rufina in 863. + 867.

864 (II)
(2) 1. Formoso, from Ostia or Corsica, bishop of Porto in 864. (1)

(1) Pope John VIII excommunicated and deposed him in 876. Exiled in France, he was recalled to Rome and reinstated as bishop of Porto by Pope Marinus I in 883. Elected Pope Formosus on October 6, 891. Died on April 4, 896. His body was exhumed and he was tried and excommunicated by Pope Stephen V (VI) in January 897, nine months after his death. Buried in a common grave and later thrown in the river Tiber. A hermit retrieved his body and reburied him. He was rehabilitated by Pope John IX in the Roman Synod of April 898.

867 (III)
(3) 1. Gauderico (or Gaudenzio), O.S.B.Cas., bishop of Velletri in 867. + (?). (1)
(4) 2. Leone, title of Ciriaco alle Terme in 867. + (?). (2)
(5) 3. Leone (?), title of S. Lorenzo in Lucina in 867. + (?). (6) 4. Leone, title of S. Cecilia in 867. + Before 872.
(7) 5. Paolo (?), title of S. Balbina in 867. + Before 872.
(8) 6. Romano Marin, from Gallese, Tuscany, nephew of Pope Marinus I, cardinal priest in 867, his title is not known. (3)
(9) 7. Giovanni, Roman, cardinal deacon in 867, his deaconry is not known. (4)

(1) Resigned cardinalate in 879 and returned to the monastery of Monte Cassino.
(2) Annuaire Pontifical Catholique, 1926, p. 153, indicates that without a doubt he is the same as Cardinal Leone, no. 15 under Pope Leo IV.
(3) Elected Pope Romanus in July or August 897. He died in November 897.
(4) Elected Pope John VIII on December 14, 872. He died on December 16, 882.

868 (I)
(1) 1. Donato (bishop of Ostia). + 870.

869 (II)
(2) 1. Tedone (bishop of Silva Candida or Santa Rufina). + After 872.
(3) 2. Paolo (bishop of Albano). + Before 898.

872 (III)
(4) 1. Leone (bishop of Silva Candida or Santa Rufina). + Before 879.
(5) 2. Benedetto (title of S. Balbina). + (?).
(6) 3. Germano (title of Ss. Giovanni e Paolo). + (?).
(7) 4. Giovanni (title of S. Cecilia). + (?).
(8) 5. Giovanni (title of S. Crisogono). + (?).
(9) 6. Paolo (his deaconry is not known). + (?).
(10) 7. Leone (his deaconry is not known). + (?).

Unknown date (IV)
(11) 1. Pietro (title is not known). + (?).

875 (I)
(1) 1. Pietro (title of S. Crisogono). + (?). (1)
(2) 2. Adriano (title of S. Lorenzo (in Damaso?)). + (?).

876 (II)
(3) 1. Walpert (bishop of Porto). + (?).

878 (III)
(4) 1. Eugenio (bishop of Ostia). + Before 898.

879 (IV)
(5) 1. Gregorio (bishop of Silva Candida or Santa Rufina). + Before 884.
(6) 2. Leone (bishop of Sabina). + Long before 928.

880 (V)
(7) 1. Marino (his deaconry is not known). (1)
(8) 2. Giovanni (his deaconry is not known). + ca. 880.

(1) Elected Pope Marinus I in December 882. He died on May 15, 884.

882 (I)
(1) 1. Basilio (title of Ss. Quattro Coronati). + 882.
(2) 2. Stefano (title of Ss. Quattro Coronati). (1)

(1) Elected Pope Stephen V (VI) toward the end of September 885. He died at the end of September 891.

883 (II)
(3) 1. Valentino (bishop of Porto). + 883.

884 (III)
(4) 1. Benedetto (bishop of Silva Candida or Santa Rufina). + Before 906.

Unknown date (IV)
(5) 1. Adriano (his title or deaconry is not known). (1)

(1) Elected Pope Adrian III on May 17, 884. He died in mid-September 885. His cultus was confirmed on June 2, 1891. His feast, according to the Roman Martyrology, is celebrated on July 8.

Elected pope on May 17, 884. He died in August or September 885. No names of new cardinals are found in his pontificate.

890 (I)
(1) 1. Giovanni (title is not known). + (?).

Unknown date (II)
(2) 1. Sergio (title or deaconry is not known). (1)

(1) Elected Pope Sergius III on January 29, 904. He died on April 14, 911.

891 (I)
(1) 1. Silvestro (bishop of Porto). + 898.

896 (I)
(2) 1. Giovanni (bishop of Velletri). + 898.
(3) 2. Benedetto (title is not known). + (?).
(4) 3. Martino (title is not known). + (?).
(5) 4. Giovanni (deaconry is not known). + (?).
(6) 5. Pasquale (deaconry is not known). + (?).
(7) 6. Giovanni (deaconry is not known). + (?).
(8) 7. Leone (deaconry is not known). + (?).

Unknown date (II)
(9) 1. Benedetto (title of S. Lorenzo in Damaso) + (?).
(10) 2. Pietro (title of S. Eudoxia (S. Pietro in Vincoli)) + (?).
(11) 3. Bonifacio (title is not known). (1)
(12) 4. Stefano (deaconry is not known). (2)
(13) 5. Teodoro (deaconry is not known). (3)
(14) 6. Giovanni, O.S.B. (deaconry is not known). (4)

(1) Elected Pope Boniface VI on April 11, 896. He died on April 26, 896.
(2) Elected Pope Stephen VI (VII) in May or June 896. He died in July or August 897.
(3) Elected Pope Theodore II in December 897. He died in December 897 or January 898.
(4) Elected Pope John IX in December 897 or January 898. He died between January and May 900.

Elected pope on April 11, 896. He died on April 26, 896. No names of new cardinals are found in his pontificate.

Elected pope in May or June 896. He died in July or August 897. No names of new cardinals are found in his pontificate.

Elected pope in July or August 897. He died in November 897. No names of new cardinals are found in his pontificate.

Elected pope in December 897. He died in December 897 or January 898. No names of new cardinals are found in his pontificate.

898 (I)
(1) 1. Stefano (bishop of Ostia). + Before 900.
(2) 2. Pietro (bishop of Albano). + (?).
(3) 3. Leone (title is not known). (1)

(1) Elected Pope Leo V in July 903. He died in September 903.

900 (II)
(1) 1. Guido (bishop of Ostia). + Before 946.
(2) 2. Cristoforo (title of S. Lorenzo in Damaso). (1)

(1) He deposed Pope Leone V and installed himself in his place in September 903, taking the name Christopher. He is listed by the sources as both pope and antipope. The official list of popes in Annuario Pontificio per l'anno 2009 (Cittá del Vaticano : Libreria Editrice Vaticana), p. 12*, has him as antipope. He was deposed and imprisoned by Pope Sergius III in January 904. Some authors say that he spent the rest of his life in a monastery and others say that he was murdered in prison. He did not create any pseudocardinals.

SUMMARY
Leo III (795-816) - 12 cardinals
Stephen IV (V) (816-817) - No names of new cardinals are found in his pontificate
Paschal I (817-824) - 4 cardinals
Eugenius II (824-827) - 8 cardinals
Valentine (827) - No names of new cardinals are found in his pontificate
Gregory IV (827-844) - 3 cardinals
[Antipope] John (844) - No names of new pseudocardinals are found in his pontificate
Sergius II (844-847) - 4 cardinals
Leo IV (847 - 855) - 32 cardinals
Benedict III (855-858) - No names of new cardinals are found in his pontificate
[Antipope] Anastasius Bibliotecarius (855) - No names of new pseudocardinals are found in his pontificate
Nicholas I (858-867) - 9 cardinals
Adrian II (867-872) - 11 cardinals
John VIII (872-882) - 8 cardinals
Marinus I (882-884) - 5 cardinals
Adrian III (884-885) - No names of new cardinals are found in his pontificate
Stephen V (VI) (885-891) - 2 cardinals
Formosus (891-896) - 12 cardinals
Boniface VI (896) - No names of new cardinals are found in his pontificate
Stephen VI (VII) (896-897) - 3 cardinals
Romanus (897) - No names of new cardinals are found in his pontificate
Theodore II (897) - No names of new cardinals are found in his pontificate
John IX (898-900) - 2 cardinals
Total - 115 cardinals