Which pope authorized the creation of the Spanish Inquisition?

Pope Sixtus IV authorized the creation of the Spanish Inquisition.

On November 1, 1478, Sixtus IV issued the papal bull Exigit sincerae devotionis affectus, authorizing Ferdinand II of Aragon and Isabella I of Castile to establish an Inquisition in the Kingdom of Castile. This created the institutional foundation for what became known as the Spanish Inquisition.

The monarchs’ request was closely connected to concerns about conversos—Jews who had converted to Christianity—as Spanish authorities feared that some converts were secretly continuing Jewish religious practices. Unlike earlier medieval inquisitions, the new tribunal was strongly shaped and controlled by the Spanish crown.

Sixtus IV later became troubled by abuses and disputes over jurisdiction. In 1482, he criticized serious excesses and attempted to limit some inquisitorial practices. Thus, the pope authorized the institution, but the Catholic Monarchs and their officials directed its development and day-to-day operation.