Rusty from the Ocean's Eleven series is almost always shown eating something in every scene. According to Brad Pitt, it was decided that Rusty would just eat all the time. He first mentioned this when he was eating after having worked all day without a break for lunch and was hungry, because he thought it would be a good character trait for Rusty Ryan as well. This leads to a gag at the end of the film where Rusty gets heartburn and throws the food away.
Stan Laurel's character in the Laurel and Hardy movies and shorts was known for this.
The Kid from Dick Tracy. "When do we eat?" (Justified, of course, because he hasn't had much to eat for a long time, and is malnourished. The opening scene of the movie shows him eating a sandwich from a trash can.)
The petite Cookie Campbell from One Crazy Summer is given a huge bag of popcorn larger than her entire body, which she effortlessly finishes in a matter of minutes. She shows no signs at all of having an even slightly fuller stomach afterwards.
In The Amazing Spider-Man, Peter Parker is one of these the night he gains his powers - implied to be a side effect of being bitten by the spider.
Pat from The Mad Miss Manton is stylishly fit, but never seems to be without food in her hand or stomach.
Marge Gunderson in Fargo. She is seven months pregnant, so this might not be her normal eating pattern at other times of her life, but certainly is in the movie.
In Kindergarten Cop, Phoebe O'Hara is not thin, but she is very small, and Kimble expresses disbelief at how much she can eat. It backfires on her when she catches food poisoning on the plane, listing all the food she ate on the way. Later she goes to a restrurant with Kimble and starts ordering most of the things on the menu.
Kevin from Home Alone. Oh god, Kevin. For a 10 year old, he's a complete glutton. In the second movie, he spends $967 on room-service all for himself and he eats everything(he does it off-screen though). And even without this, he wolfs away an enormous amount of food in both movies.
One scene in R.O.T.O.R. shows the protagonist and his ladyfriend having lunch in a restaurant. The next time we see them, it is early afternoon of the same day, and they are preparing to cook themselves two steaks the size of toilet seats.
In Pixels, Q*Bert eagerly eats everything Sam and Matty give him, and they feed him a lot.
Drippy from Wild Child. She's a petite and thin 16 year old, but she eats more than a whale. She sneaks into the school's freezer almost every night to stuff her face with ice cream. And she can't stop herself from buying cream eggs when she trying to buy alcohol with her friends.
Little John in Beyond Sherwood Forest, who constantly suggests stopping for a meal, mentions how long it has been since they last ate, and even finds some local fruit to eat while they are in the Dark Woods.
Venom (2018): If the symbiote doesn't get a lot of food, it will end up destroying Eddie's internal organs, and neither of them particularly wants that. In the initial infestation period, the symbiote drives Eddie to eat everything remotely edible in his apartment, no matter how frozen or decayed, and regularly demands food for the rest of the movie. It also has a particular taste for people, particularly the heads, which it swallows whole and apparently digests in a matter of seconds. At one point it swallows an entire person without chewing. Since the symbiote is taking most of it, Eddie never puts on any notable weight in the process.
The Disaster Artist: Tommy is frequently shown eating at restaurants from several plates of food, usually including pizza. In spite of this, he maintains his creepily muscular physique.
A scene in The Nutty Professor 2 shows the Klumps walking like Determinators towards an all-you-can-eat buffet. The family ends up eating everything but the salad. Also, first film has two dinner scenes with the Klumps displaying the amount of food on the table.
The title character of Fat Girl displays signs of Compulsive Eating. Her sister constantly puts Anaïs down for her weight and her constant eating, but also encourages Anaïs to eat when trying to cheer her up.
Fatso stars Dom De Luise as an obese man with an eating problem who has to choose between conforming to other people's expectations and dieting or being himself but remaining unhealthy.
Rosemary in Shallow Hal always eats big. She sucks down a chocolate milkshake while Hal's head is turned for a few seconds, and later, slices off a "sliver of cake" to eat... which is a third the size of the whole cake.
Jen: "Um ... do you want a plate?"
Rosemary: [shaking her head with her mouth full] "Un-uh."
Hal: [unaware of Rosemary's true girth] "I know what you're thinkin', where does she put it?"
Bedazzled (1967) — George (the Devil) tries to cheer up a despondent Stanley by going to a fun park with a couple of fun girls - the Deadly Sins Avarice and Gluttony. Avarice is constantly carping about getting things, and Gluttony is constantly stuffing her face.
All three of the Ghostly Trio in Casper are Big Eaters, but Fatso (true to his name) is the only one who's actually fat.
Earl, a minor character in Diner, orders the entire left side of the menu, which is 22 deluxe sandwiches plus the fried chicken dinner.
Modell: He's not human, he's not a person. He's like a building with feet.
This is a trait that is shared by hobbits and dwarves in The Hobbit, as seen when the dwarves raided Bilbo's pantry. But it's averted with Thorin who is only seen eating from a small bowl and plate.
Thor has Volstagg, though considering his great strength and fighting ability, this is likely a side effect of his Stout Strength. Thor himself is also a voracious eater, showing off his Boisterous Bruiser nature. Stout or slender, Asgardians are a race of big eaters.
In Pixels, Pac-Man, as could be expected. He's seen munching through cars and buildings like they're made of cheese.
Dennis Nedry from Jurassic Park is one, first being seen polishing off an unhealthily large meal that takes up his entire table at a restaurant. Even after he's handed a big bag of money, he still forces Dodgson to pay for his huge bill. Later, his work station is a complete mess of candy and snack wrappers, and he is able to convince his superiors he's going to a vending machine just by virtue of his obesity. If Nedry had escaped from the island with the dinosaur DNA, and with the seemingly limitless flow of cash coming to him in return, it's likely Nedry would've gotten to the size of a Hutt since he probably would've spent much of his new wealth on food.
Terri in Reform School Girls. When the girls are working in the field and waiting for lunch, she complains every time one of them mentions food as she is starving. She later takes advantage of the Prison Riot to grab food and scarf it down rather than rioting.
In Terror in a Texas Town, Fat Bastard McNeil is eating or drinking in every scene he is, and has lobsters and oysters imported from the east coast for his personal delectation.