Pope Innocent IV (Latin: Innocentius IV; c. 1195 – 7 December 1254), born Sinibaldo Fieschi, was head of the Catholic Church and ruler of the Papal States from 25 June 1243 to his death in 1254.
Fieschi was born in Genoa and studied at the universities of Parma and Bologna. He was considered in his own day and by posterity as a fine canonist. On the strength of this reputation, he was called to the Roman Curia by Pope Honorius III. Pope Gregory IX made him a cardinal and appointed him governor of the Ancona in 1235. Fieschi was elected pope in 1243 and took the name Innocent IV. He inherited an ongoing dispute over lands seized by the Holy Roman Emperor, and the following year he traveled to France to escape imperial plots against him in Rome. He returned to Rome in 1250 after the death of the Emperor Frederick II.
On 15 May 1252 he promulgated the bull Ad extirpanda authorizing torture against heretics, equated with ordinary criminals.