Pope Gregory X (Latin: Gregorius X; c. 1210 – 10 January 1276), born Teobaldo Visconti, was head of the Catholic Church and ruler of the Papal States from 1 September 1271 to his death and was a member of the Third Order of St. Francis. He was elected at the conclusion of a papal election that ran from 1268 to 1271, the longest papal election in the history of the Catholic Church.
He convened the Second Council of Lyon and also made new regulations in regards to the papal conclave. Gregory was beatified by Pope Clement XI in 1713 after the confirmation of his cultus.