The Spanish Inquisition was independent of the medieval Inquisition. It was established (1478) by Ferdinand and Isabella with the reluctant approval of Sixtus IV. One of the first and most notorious heads was Tomas de Torquemada. It was entirely controlled by the Spanish kings, and the pope's only hold over it was in naming the inquisitor general. The popes were never reconciled to the institution, which they regarded as usurping a church prerogative.
The purpose of the Spanish Inquisition was to discover and punish converted Jews (and later Muslims) who were insincere. However, soon no Spaniard could feel safe from it; thus, St. Ignatius of Loyola and St. Theresa of Ávila were investigated for heresy. The censorship policy even condemned books approved by the Holy See. The Spanish Inquisition was much harsher, more highly organized, and far freer with the death penalty than the medieval Inquisition; its autos-da-fé became notorious. The Spanish government tried to establish the Inquisition in all its dominions; but in the Spanish Netherlands the local officials did not cooperate, and the inquisitors were chased (1510) out of Naples, apparently with the pope's connivance. The Spanish Inquisition was finally abolished in 1834.