In Preacher, there's Allfather D'Aronique, the original leader of The Grail before Herr Starr takes it over - he's too fat to move under his own power, and bulimic to boot. He's so heavy that he wrecks passenger jets upon landing.
Starr, While watching a jet's landing gear break: Every fucking time...
The Blob from X-Men is a possible example. In the comics, his bulk is due to his mutation, but in X-Men: Evolution, he was already very fat before he developed his powers.
Another Marvel villain, the Slug, a drug czar from Miami, is nearly twice the size of the Kingpin, and could smother people in the folds of his fat. He can also barely move at all, though. As you might expect, he's a joke.
While not fat, Agent Orange, leader of the Orange Lantern Corps in The DCU. In the emotional spectrum, Orange represents selfishness and greed, and Agent Orange is the greediest creature to ever live; When the Controllers discovered his secluded base, they discover he'd been revelling in the consumption of extremely rotten and disgusting food. True to form, he's the only true member of the corps; the others are all spirits of the people he killed in his constant search for more. Interrupting his meal is also the reason why he's became active again. The Orange Lanterns under his thrall are all immensely greedy themselves, including among their number a literal god of hunger and Glomulus, who was used as a garbage disposal all his life. Agent Orange's hunger is in fact a direct result of being the bearer of the orange light of avarice. He is constantly plagued by a hunger that is seemingly impossible to satisfy no matter how much he eats. When Green Lantern Hal Jordan tried taking away his orange power battery it exerted a similar effect, and even though he just held onto it for a second or so he was starving right after. Leads to a Crowning Moment of Funny when he arrives at a casino hotel in Vegas. When he spots the "All-you-can-eat" Buffet, he reacts like a pilgrim finally reaching Mecca.
Gregorian Falstaff was a Corrupt Corporate Executive business rival of Bruce Wayne in the Batman comics in the 1980s (and ultimately a front man for Ra's al Ghul). He was always depicted eating, usually with a leg of lamb in his hand like Henry the Eighth.
In Tomorrow Stories, one of the First American's recurring enemies is Fatwah Arbuckle, the Guzzlin' Muslim. He's really not evil so much as he has this crazy appetite, but what are you gonna do?
General Tara of Tarakimo in The Phantom is a classic self-indulgent crassly fat villain. He gobbles whole chickens with only his hands while seated on a throne, and his over-decorated dress unniforms barely disguise his big belly. Obesity, overall, is a characteristic shared by many of the bad guys in this strip.
X-Men villain Shadow King is a particularly sadistic example. He's a demonic psychic entity that becomes addicted to eating whenever he possesses someone. Shadow King ruins other peoples' physiques while satisfying his own cravings. The really horrifying part is that this isn't even the worst thing Shadow King does to his hosts/victims.