Pope Sixtus IV (Italian: Sisto IV: 21 July 1414 – 12 August 1484), born Francesco della Rovere, was head of the Catholic Church and ruler of the Papal States from 9 August 1471 to his death. His accomplishments as pope included the construction of the Sistine Chapel and the creation of the Vatican Archives. A patron of the arts, he brought together the group of artists who ushered the Early Renaissance into Rome with the first masterpieces of the city's new artistic age.

Sixtus founded the Spanish Inquisition through the bull Exigit sincerae devotionis affectus (1478), and he annulled the decrees of the Council of Constance. He was noted for his nepotism and was personally involved in the infamous Pazzi conspiracy.