Francisco Guzman was a 13th century contender for the papacy, and part of the Spanish Inquisition. He had his main rival for the position, Chretien d'Alsace, killed.

He tried to discredit the Cathares by convincing them a skull was that of Jesus Christ and thus a holy relic. When they were found with it, they would be accused of trying to usurp Catholic power. The plan failed when the Seventh Doctor was able to smuggle the skull to the Knights Templar. He did not know the Templars were spying on him and were aware of all his scheming. They revealed his involvement in the murders of d'Alsace and de Citeaux, ruining his dreams of becoming pope. (PROSE: Sanctuary)