The Catholic Encyclopedia
notes the historically obscure resignations of Pope Pontian
(230-235) and Pope Marcellinus
(296-308), the historically postulated resignation of Pope Liberius
and that one (unspecified) catalogue of popes lists Pope John XVIII
as resigning office in 1009 and ending his life as a monk
The first historically unquestionable
Papal resignation is that of Pope Benedict IX
in 1045. In order to rid the Church of the scandalous Benedict, Pope Gregory VI
gave Benedict "valuable possessions"
to resign the papacy in his favour.
Gregory himself resigned in 1046 because the arrangement he had entered into with Benedict was considered simony
. Gregory's successor, Pope Clement II
, died in 1047 and Benedict IX became Pope again.
The best-known resignation of a Pope is that of Pope Celestine V
in 1294. After only five months of pontificate, he issued a solemn decree declaring it permissible for a Pope to resign, and then did so himself. He lived two more years as a hermit
and then prisoner of his successor Pope Boniface VIII
and was later canonised
. Celestine's decree, and that of Boniface concurring, ended any doubt among canonists about the possibility of a valid Papal resignation.
Pope Gregory XII
(1406-1415) resigned in 1415 in order to end the Western Schism
, which had reached the point where there were three claimants to the Papal throne: Roman Pope Gregory XII, Avignon Antipope Benedict XIII
, and Pisan Antipope John XXIII
. Before resigning he formally convened the already existing Council of Constance
and authorized it to elect his successor.