After a two-year impasse with no new Pope, the Cardinals elected a hermit monk who sent them an angry letter, threatening them with divine judgement. He became Celestine V. He served for five months before implementing a law that allowed Popes to abdicate. He abdicated a week later.

Pope Celestine V

Pope Celestine V (Latin: Caelestinus V; 1215 – 19 May 1296), born Pietro Angelerio (according to some sources Angelario, Angelieri, Angelliero, or Angeleri), also known as Pietro da Morrone, Peter of Morrone, and Peter Celestine, was pope for five months from 5 July to 13 December 1294, when he resigned. He was also a monk and hermit who founded the order of the Celestines as a branch of the Benedictine order.

He was elected pope in the Catholic Church’s last non-conclave papal election, ending a two-year impasse. Among the few edicts of his to remain in force was the confirmation of the right of the pope to abdicate; nearly all of his other official acts were annulled by his successor, Boniface VIII. On 13 December 1294, a week after i… Continue Reading

Source: https://en.wikipedia.org/wiki/Pope_Celestine_V