A glutton or a fat person. Derived from Vitellius, who was both a glutton and a fat person, who was Emperor of Rome in 69 A.D. and whose short reign was notable only for his incredible gluttony. Vitellius was an obese glutton who was notoriously lazy and self-indulgent, spent most of his time as emperor eating at luxurious banquets four or five times a day, all paid for with tax money. He would send the Roman Navy to procure rare foods for his banquets.
Todd: "Jan is such a Vitellius."
Scott: "Yes. She eats at her desk all day and is way too fat and unhealthy."
Todd: "If she would get some exercise or not eat as much then maybe she wouldn't be a Vitellius."
Scott: "I don't know . . . she is quite a glutton and she spends a lot of money on stuff."