1. St. Peter (32 - 67)
Peter was allegedly the first pope, at least according to Catholic tradition, as well as the one who brought Christianity to Rome. All the evidence indicates, however, that Christianity came to Rome well before he would have and even once there he didn't serve as bishop or any sort of leader.
10. St. Pius I (140 - 155)
First real bishop of Rome. Prior to this the Christian community was governed by a council of elders or deacons. Pius was the first "bishop" who exercised sole authority.
14. St. Victor I (189 - 199)
First African pope.
First pope to attempt to exert authority outside Rome and neighboring communities. He threatened excommunication for anyone who refused to celebrate Easter on Sunday and was soundly rebuked for it at this time, the bishop of Rome wasn't justified in telling others what to do like this.
18. St. Pontain (230 - 235)
First pope to resign his office.
40. St. Innocent I (401 - 417)
First pope whose father was also a pope, Anastasius I. Had Anastasius' marriage not been valid, Innocent would have been an illegitimate child and therefore ineligible for the priesthood.
45. St. Leo I (the Great) (440 - 461)
First pope to explicitly claim authority over the entire Christian Church, East and West.
49. St. Gelasius I (492 - 496)
First pope to use the title "Vicar of Christ."
Last pope of African descent (born in Rome, though).
51. St. Symmachus (498 - 514)
First pope to give a pallium to a bishop outside of Italy. The pallium is a woolen garment worn by bishops as a sign of their pastoral authority.
55. Boniface II (530 - 532)
First pope with German heritage (but he wasn't born in German lands).
56. John II (533 - 535)
First pope to adopt a new name when elected but even then, only because his given name was of the pagan god Mercurius.
58. St. Silverius (536 - 537)
Second pope whose father was also a pope (Hormisdas).
First pope who was subdeacon at the time of his election.
60. Pelagius I (556 - 561)
First pope not actually elected at all he was simply appointed by emperor Justinian.
72. John IV (640 - 642)
First (and thus far only) pope from Dalmatia.
90. St. Gregory III (731 - 741)
Last pope to seek approval from the emperor in Constantinople. Before this, every pope had to get approval from either the emperor or his exarch in Ravenna before assuming office sometimes resulting in delays that lasted months between an election and a coronation.
91. St. Zachary (741 - 752)
Last Greek pope.
93. Stephen III (II) (752 - 757)
Organized the papal states and made the papacy independent of the Byzantine Empire by placing it under the protection of the Franks.
94. St. Paul I (757 - 767)
First pope who succeeded his own brother, Stephen III.
95. Stephen IV (III) (767 - 772)
Declared that the laity could not have any voice in the election of popes anymore.
96. Adrian I (772 - 795)
Oldest person elected pope (80).
97. St. Leo III (795 - 816)
First and only pope to ever formally offer obeisance to a Western emperor.
107. Adrian II (867 - 872)
Last married pope - his wife Setphania and his daughter lived in the Vatican palace with him.
108. John VIII (872 - 882)
First pope to be assassinated: first he was poisoned and then he was beaten to death.
109. Marinus I (882 - 884)
First person elected pope while already bishop of another diocese a violation of rules set down by the Council of Nicaea.
113. Boniface VI (896)
When Boniface was elected pope, he had already been defrocked twice because of immoral behavior.
114. Stephen VII (VI) (896 - 897)
Stephen had the body of Formosus dug up and put on trial on trumped-up charges. For his trouble, Stephen would end up being imprisoned and strangled to death.
120. Sergius III (904 - 911)
Sergius ordered the murder of his predecessor, Leo, and the antipope Christopher.
126. John XI (931 - 935)
First (and presumably only) pope who was the illegitimate son of a previous pope (Sergius III).
131. John XII (955 - 963)
First and only teenager elected pope.
132. Leo VIII (963 - 964)
First pop who was a layman at the time of his election.
138. John XV (985 - 996)
First pope to canonize a saint (Ulrich of Augsburg, 993).
139. Gregory V (996 - 999)
First German-born pope.
140. Sylvester II (999 - 1003)
First French pope.