Pope Celestine V, born Pietro Angelerio, 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.

Celestine was in his eighties when he was elected pope on July 5, 1294. He accepted only because of the perilous situation of the church: the papacy had been vacant for two years. Though a holy man, he lacked administrative ability and considered the papacy a distraction from his ascetic struggle for salvation. He distrusted the cardinals and became dependent on King Charles II of Naples, with whose supporters he filled the Curia. Further, he favoured his own hermits and the Franciscan Spirituals, whom he permitted to secede from the main part of their order, a solution that was much later made permanent after long struggle.

After Cardinal Benedict Caetani became his successor as Boniface VIII, some claimed the resignation unlawful. Thus the majority of the cardinals found it advisable to keep Celestine under supervision, and he was not allowed to return to his hermitage. On the verge of escaping via the Adriatic Sea, he was captured and sent back to Boniface, who kept him interned in Fumone Castle, where he died.

Celestine was canonized on 5 May 1313 by Pope Clement V.