Juan de Marillo (died 1492) was an Inquisitor serving under the Grand Inquisitor Tomás de Torquemada. He was given responsibility to purge the city of Granada of heretics in the immediate aftermath of its fall to Spain.
In 1491, Spain was on the verge of victory in its final war against the Emirate of Granada. Despite their imminent defeat, the Moors refused to surrender. In truth, the Templars had captured Emir Muhammad XII in his palace of Alhambra; their plan was force him to prolong the war indefinitely so as to exhaust the Spanish treasury from funding Christopher Columbus's voyage to the Americas. Towards the end of the year, the Spanish launched yet another attack on the capital of Granada in their months-long siege. During this last assault, the Assassin Ezio Auditore da Firenze infiltrated the Alhambra, freed Muhammad XII from the Templars and persuaded him to surrender.
In the aftermath of the war, the Spanish Inquisition acted promptly in purging Granada of those they deemed heretical—before Muhammad XII had even formally abdicated. Juan de Marillo was bequeathed authority over this matter by the Grand Inquisitor Tomás de Torquemada, and he sent out soldiers to execute blind arrests of numerous civilians innocent of any wrongdoing.
Unbeknownst to Juan, his operation attracted the immediate attention of the Assassins, who had just saved the city from being razed by the Spaniards. While Juan prepared to rendezvous with Torquemada in secret in the catacombs, many of his forces in the city conducting their arrests were being killed off by Ezio to rescue the populace.
At his meeting with the Torquemada, Juan reported that Emir Muhammad XII's life had been spared by Queen Isabella I of Castile following his surrender, an act of mercy of which Torquemada disapproved. Torquemada then ordered Juan to sweep the entire city for any who refused to profess allegiance to the Pope and expel them by force, adding that he had free reign to punish those that resisted in whatever way he saw fit.
After Torquemada left, Juan repeated this command to his lieutenant. His guards had only just left when he was swiftly assassinated by Ezio, who had overheard the entire conversation in his search for the inquisitor responsible for the arrests. Ezio had went through great lengths to ensure that no one bore witness to the assassination and that it was delivered as silently as possible. With his death an absolute secret, and his body lying in the darkness of the catacombs, Juan effectively disappeared, forestalling any possibility of the Inquisition using his murder to escalate their operation in retaliation.