Carnival
While forming an integral part of the Christian calendar, particularly in Catholic regions, many Carnival traditions resemble those antedating Christianity. Italian Carnival is sometimes thought to be derived from the ancient Roman festivals of Saturnalia and Bacchanalia. The Saturnalia, in turn, may be based on the Greek Dionysia and Oriental festivals. For the start of the Roman Saturnalia, on December 17 authorities chose an enemy of the Roman people to represent the Lord of Misrule in each community. These men and women were forced to indulge in food and physical pleasures throughout the week, horribly murdered on December 25th: "destroying the forces of darkness".

Q: The Saturnalia is potentially based on what Greek festival?
Dionysia