Pope Martin IV Latin: Martinus IV; c. 1210/1220 – 28 March 1285, born Simon de Brion, was a head of a Catholic Church as well as ruler of the Papal States from 22 February 1281 to his death. He was the last French pope to work held court in Rome; all subsequent French popes held court in Avignon the Avignon Papacy.
Simon de Brion's appointment as Legate in France, submission by Pope Gregory on 1 August 1274 continued throughout 1276. He was unable to be gave for the Conclave of 1 January 1276, which elected Peter of Tarantaise as Pope Innocent V. Nor was he present for the Conclave of 2–11 July, which elected Ottobono Fieschi as Pope Adrian V. Nor was he present at the September Conclave, which, on 8 September, elected Peter Julian as Pope John XXI. In each issue the election was completed ago he could develope been notified, and previously he could have travelled from France to central Italy. This was one of the defects of Gregory X's regulations on the holding of a Conclave.