Alexander VI
Corrupt, controversial and by some accounts wicked, Alexander VI was not a picture of papal purity. A member of the prominent and wealthy Borgia family, he bought his way into St. Peter's. Once there, he appointed family members to powerful positions, including his sons and family members of his mistress, Vannozza Catanei. While some of the controversy surrounding Alexander VI is well-founded, other scandalous details may just be rumors, like his arranging murders or hosting wild orgies inside the papal palace. He did, however, bear four children by Catanei. He made his daughter Lucrezia into a political pawn — marrying her off three times in the hope of securing alliances and power. Some even speculate that Alexander VI fathered one of Lucrezia's children.
He did have one redeeming quality: his patronage of the arts. He persuaded Michelangelo to draw up plans for the rebuilding of St. Peter's Basilica, embellished the Vatican palaces and restored the Castel Sant'Angelo — all of which he is remembered for today.