Alexander VI took the office in 1492 (the year Columbus sailed something), and was part of the notorious Borgia family of Renaissance Italy. The Borgias were really something of a scourge on Italy - they were rich, powerful, completely without scruple, and deadly. They became famous for poisoning people.

Alexander himself led a debauched life, hanging out with Saracen captives, holding feasts with prostitutes, making boatloads of money selling indulgences, starting wars, and even financing his own iniquitous empire by 'confiscations': arresting rich church officials on spurious accusations, and confiscating their wealth for his own use. He was admired by Machiavelli.

He ruled from 1492 until his death in1503. His body, which may have been poisoned, exhibited signs of fantastic decomposition. Contemporary observers said that the body was, "the ugliest, most monstrous and horrible dead body that was ever seen, without any form or likeness of humanity." This kind of super-decomposition is sometimes thought of as a sign of God's particular disapproval.*

*Like how vampires dissolve into dust? Or witches melt? I think we've still got the idea stuck pretty deep in our brains.