Pope Gregory X (Latin: Gregorius X), born Teobaldo Visconti, was Pope from 1 September 1271 to his death in 1276 and was a member of the Secular Franciscan Order. 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 Lyons and also made new regulations in regards to papal conclaves. Though briefly annulled by Pope Adrian V and Pope John XXI, these regulations remained in force until the 20th century, when they were altered by Pope Paul VI.
Pope Clement XI beatified him in 1713 after the confirmation of his cultus.