Pope Gregory XI (c. 1336 - March 27, 1378), born Pierre Roger de Beaufort, Pope from 1370 to 1378, born in Rosiers-d'Égletons, Limousin around 1336, succeeded Pope Urban V (1362-70) in 1370 as one of the Avignon Popes.

During his pontificate vigorous measures were taken against the heresies which had broken out in Germany, England, and other parts of Europe; a sincere effort was also made to bring about a reformation in the various monastic orders. The nineteen propositions of John Wycliffe (c. 1320-84) and the thirteen articles of the Sachenspiegel were formally condemned by Pope Gregory XI in 1377.

His return to Rome is attributed in part to the stirring words of Catherine of Siena, January 27, 1377. This had been attempted by Gregory's predecessor, Urban V, without success. The project was delayed by a conflict between the pope and Florence, known as "the War of the Eight Saints" for the "Eight for War," the Florentine magistrates responsible for the conduct of the war. The pope put Florence under interdict for a time.

Gregory XI did not long survive this removal, dying on March 27, 1378. His successor was Pope Urban VI (1378-89), but the antipope Clement VII (1378-89) also received much support, and the Western Schism (1378-1417) lasted almost forty years.