Pope John XXI

Born Pedro Julião around 1215, he rose through the Church while possibly doubling as Peter of Spain, a logician and herbalist whose medical texts circulated widely. On 8 September 1276 he became head of the Catholic Church and ruler of the Papal States. His papacy lasted less than a year. He died on 20 May 1277, leaving behind the singular distinction of Portugal's only pope and, if the identification holds, the only doctor to reach the Chair of Peter.