Pope Gregory IX, (b. 1143)
Pope Gregory IX (Latin: Gregorius IX; born Ugolino di Conti; c. 1145 or before 1170 – 22 August 1241) was Bishop of Rome and hence head of the Catholic Church and ruler of the Papal States from 19 March 1227 till his death. He is known for issuing the Decretales and instituting the Papal Inquisition, in response to the failures of the episcopal inquisitions established during the time of Pope Lucius III, by means of the papal bull Ad abolendam, issued in 1184.

The successor of Honorius III, he fully inherited the traditions of Gregory VII and of his own cousin Innocent III and zealously continued their policy of papal supremacy.