WordNet sense 1 ((Roman Catholic Church) a church father known for his constant fight against perceived heresies; a saint and Doctor of the Church (329-391)):

Gregory Nazianzen, Gregory of Nazianzen, St. Gregory of Nazianzen

WordNet sense 2 (Italian pope from 1831 to 1846; conservative in politics and theology; worked to propagate Catholicism in England and the United States (1765-1846)):

Bartolomeo Alberto Capillari, Gregory XVI

WordNet sense 3 (the pope who sponsored the introduction of the modern calendar (1572-1585)):

Gregory XIII, Ugo Buoncompagni

WordNet sense 4 (the Italian pope from 1406 to 1415 who worked to end the Great Schism and who retired to make it possible (1327-1417)):

Angelo Correr, Gregory XII

WordNet sense 5 (the Italian pope who fought to establish the supremacy of the pope over the Roman Catholic Church and the supremacy of the church over the state (1020-1085)):

Hildebrand, Gregory VII

WordNet sense 6 ((Roman Catholic Church) an Italian pope distinguished for his spiritual and temporal leadership; a saint and Doctor of the Church (540?-604)):

Gregory I, Gregory the Great, Saint Gregory I, St. Gregory I