List of murdered popes
Several Roman Catholic popes have been murdered. The circumstances have ranged from martyrdom (Pope Stephen I) to war (Lucius II), to a beating by a jealous husband (Pope John XII). A number of other popes have died under circumstances that some believe to be murder, but for which definitive evidence has not been found.
The full list of popes from Peter up through John Paul II, including many mentioned as martyrs, is found in I Sommi Pontifici Romani, Annuario Pontificio, and the iconography of the Basilica of Saint Paul Outside the Walls. A secondary source, Liber Pontificalis or "Book of the Popes", adds "crowned with martyrdom" for half a dozen of the first 33 popes not specifically identified as martyrs in the primary sources. Several other popes are traditionally said to have been martyred, according to the Acts of the Martyrs and other sources of unknown authenticity.
- Saint Peter (c.67), traditionally martyred by crucifixion
- Pope Linus (Saint) (c.67-c.76)
- Pope Anacletus or Cletus (Saint) (c.79-c.92)
- Pope Clement I (Saint) (c.92-c.99), thrown into sea with anchor around his neck
- Pope Evaristus (c.99-c.108); not listed in the Roman Martyrology
- Pope Alexander I (Saint) (c.106-c.119); recognition as the martyred Saint Alexander (feast day May 3) rescinded in 1960
- Pope Sixtus I (Saint) (c.119-c.128)
- Pope Telesphorus (Saint) (c.128-c.138)
- Pope Hyginus (Saint) (c.138-c.142); martyrdom dubious
- Pope Pius I (Saint) (c.142-c.154), martyred by the sword; claim of martyrdom removed from the 1969 General Roman Calendar
- Pope Anicetus (Saint) (155-166), traditionally martyred.
- Pope Soter (Saint) (166-175), died a martyr 
- Pope Eleuterus (Saint) (175-189), died a martyr 
- Pope Victor I (Saint) 189-199, died a martyr 
- Pope Calixtus I (Saint) (217-222), died a martyr 
- Pope Urban I (Saint) 222-230, died a martyr 
- Pope Pontian (Saint) 230-235, condemned to mines in Sardinia and died on island of Tavolara
- Pope Anterus (Saint) Elected 235-12-21, martyred at hands of Emperor Maximus 
- Pope Fabian (Saint) Elected 236-1-10 and died a martyr 250-1-20 during persecution by Decius
- Pope Cornelius (Saint) (Elected March 251 and died a martyr June 253).
- Pope Lucius I (Saint) Elected 253-6-25 and martyred 254-3-5.
- Pope Stephen I (Saint) Elected 254-5-12 and martyred 257-8-2.
- Pope Sixtus II (Saint) Elected 257-8-30 and martyred 258-8-6.
- Pope Dionysius (Saint) Elected 259-7-22 after year of persecutions and died 268-12-26, martyred 
- Pope Felix I (Saint) Elected 269-1-5 and died 274-12-30, martyred 
- Pope Eutychian (Saint) Elected 275-1-4 and martyred 283-12-7. 
- Pope Caius (Saint) Elected 283-12-17 and martyred 296-4-22, but not at hands of his uncle, Diocletian 
- Pope Marcellinus (Saint) Elected 296-6-30 and martyred 304-10-25 during persecution of Diocletian 
- Pope Marcellus I (Saint) Elected 308-5-27 after 4-year vacancy and martyred 309-1-16.
- Pope Eusebius (Saint) Elected 309-4-18 and martyred in Sicily 309-8-17. 
- Pope Martin I (Saint) Elected in 649. Died in exile 655-9-16
Chronological list of popes murdered
- Stephen VI (896–897): Strangled
- Stephen VIII/(IX) (939–942): Mutilated
- John XII (955–964): Presumed murdered
- Benedict VI (973–974): Strangled
- John XIV (983–984): Either by starvation, ill-treatment or direct murder
- Gregory V (996–999): Poisoned
Chronological list of popes who are alleged to have been murdered
- John VIII (872–882): Allegedly poisoned and then clubbed to death
- Adrian III (884–885): Allegedly poisoned
- Leo V (903): Allegedly strangled
- John X (914–928): Allegedly smothered with pillow
- Stephen VII/(VIII) (929–931): Allegedly murdered
- Sergius IV (1009–1012): Allegedly murdered
- Clement II (1046–1047): Allegedly poisoned
- Damasus II (1048): Allegedly murdered
- John XXI (1276-1277): While visiting the construction of a church, the roof collapsed on him, leading to conspiracy theories
- Celestine V (1294, died 1296): Held captive and allegedly murdered after his abdication, by order of his successor, Pope Boniface VIII
- Boniface VIII (1294–1303): Death possibly (though unlikely) from the effects of ill-treatment one month before
- Benedict XI (1304–1305): Allegedly poisoned; no evidence provided
- Pius XI (1922-1939): Allegedly (though unlikely), in connection with his doctor's having been the father of Benito Mussolini's mistress
- John Paul I (1978): Death just 33 days after Papal election led to conspiracy theories
- Jacobus de Voragine; William Granger Ryan. The golden legend: readings on the saints. Princeton University Press. p. 39.
- Foul Play Suspected in Popes Death? Baltimore Afro-American - October 10, 1978
- Kirsch, Johann Peter (1911), "St. Peter, Prince of the Apostles", Catholic Encyclopedia 11, New York: Robert Appleton Company, retrieved 2013-06-03
- I Sommi Pontifici Romani
- Liber Pontificalis
- Annuario Pontificio
- First pope listed as a martyr by Irenaeus' Against Heresies
- Kirsch, Johann Peter (1911), "Pope St. Hyginus", Catholic Encyclopedia 7, New York: Robert Appleton Company, retrieved 2013-06-03
- Butler, Alban (1866). "July 11: St. Pius I., Pope and Martyr". The Lives of the Saints 7. Dublin: James Duffy. Retrieved 2013-06-03.
- "Calendarium Romanum" (Libreria Editrice Vaticana, 1969), p. 129
- Pope Stephen (VI) VII New Advent.org
- Pope Benedict VI New Advent.org
- Pope John XIV NewAdvent.org
- Mann, H. (1910). Pope John VIII. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved February 14, 2010 from New Advent: http://www.newadvent.org/cathen/08423c.htm
- Pope Leo V NewAdvent.org
- Pope John X NewAdvent.org
- Pope Clement II NewAdvent.org
- "Pope Celestine V". List of Roman Catholic Popes. Retrieved 19 May 2011.
- Pope Boniface VIII NewAdvent.org
- Yallop, David A. In God's Name: An Investigation into the Murder of Pope John Paul I. Toronto: Bantam Books, 1984. ISBN 978-0-553-05073-8.