Both Alex and Max from Happy Endings-its more notable in Alex's case because she's tiny and petite, and Max is depicted as more of a fat guy, despite having a basically average build. Still, when the petite 5'3 girl and the 5'10 guy are eating roughly the same amount of food, you know which one is playing the trope straighter.
A more modest though still unrealistic form of this ability is displayed by the waifish title characters of Gilmore Girls. Lampshaded when Luke comes over to Lorelai's house and looks in the refrigerator:
Luke: There's nothing in here but ice cream, candy bars, cookie dough, frosting— why are you not 450 pounds?
Lorelai: I know. Scientists call it the Lorelai paradox.
Joey Tribbiani from Friends. In one episode he volunteers to eat a whole Thanksgiving turkey, which doesn't mean he'll stop eating until then. (He calls it "warming up.") Another episode involving Phoebe's birthday dinner at a nice restaurant. Over the course of the episode, everyone, including Phoebe, leaves for other activities... except Joey. He's bummed at first, but lights up when all of the already ordered entrees arrive.
Joey: Dinner for six for one? (to waiters) You guys are about to see something real special... (he even eats the birthday cake afterwards) Joey: This is the best birthday ever!
He even eats - and enjoys - Rachel's infamous Shepherd's Trifle. He likes it so much that he sneaks around and eats the four uneaten portions that the others couldn't manage.
Joey: What's not to like? Custard? Good. Jam? Good. Meat? Good.
Dean Winchester of Supernatural eats constantly and spends most of his life sitting in a car, but still manages to look as toned as Jensen Ackles. All the "Dean eats constantly" jokes have been getting slightly jarring recently because Jensen Ackles looks like he's lost even more weight while Jared Padalecki (the one who's never seen to be eating) looks like he could bench-press him easily.
Leviathans takes this Up to Eleven when it's found out that they want to turn humans into livestock, mostly because there's only seven billion of us...
Fred of Angel is shown to eat a lot, despite being played by the waifishly thin Amy Acker. Lampshaded when, after a breakfast with Gunn, he says "Where do you put it all in that little tiny body?"
Upon being invited for dinner at the Summers home, Faith is ravenously shoveling food down her throat and sneaking food off of Buffy's plate. Slayers in general are big eaters, Faith was just the first one to demonstrate it onscreen. Apparently, Slaying makes them "Hungry and Horny". Given Faith's living situation, it's quite possible she hadn't eaten for a while.
Buffy is apparently more sneaky about it.
Giles: All I know is, the fate of the entire world may well depend on... (sees donut box) did you eat all the jellies? Buffy: ... Did you want a jelly? Giles: I always have jelly; I'm always the one who says "Let's have some jellies in the mix"! Willow: We're sorry.... Buffy had three!
Sylar is often seen snacking on something and clearly enjoyed eating an entire pie by himself. A video montage was collected of how many times he's been seen onscreen with food. He also makes frequent references to food and his desire for abilities is often described as a "hunger".
Samantha Marquez on Las Vegas is Front Of House's secret weapon during a hot dog eating contest against Back of House, despite Vanessa Marcil looking like she's never even touched a hot dog. Sam brags that her nickname used to be "Hummingbird", since she could eat twice her body weight.
An episode of Stargate SG-1 has the team's metabolism boosted by alien devices. The sneak off base and go for steak. Jack orders three steaks, and calls the waitress back with the "That's just for me" line while Carter and Daniel order the same. Then Carter adds And a Diet Coke. (When she gets the look, she explains that she likes the taste.)
From Stargate Atlantis, Dr. McKay is a big eater. He's not terribly discriminating, either — the only thing he doesn't like about airline food is they won't give him seconds. Except for any food including citrus, which he's allergic to.
The Androgums in "The Two Doctors" had huge appetites and would eat just about anything, including their own species.
In The End Of Time, The Master has been revived, but he's...not quite right. One of many unsettling effects include an intense, intense hunger. At a food stall, he orders everything they have in stock, and devours it all at high speed. In another scene, he eats an entire roasted chicken within a minute.
Chuck Noblet in Strangers with Candy is constantly eating at his desk, which turns out to be foreshadowing for "Feather in the Storm" when we find out he's bulimic.
There is an ongoing gag about how much Liz Lemon loves to eat, especially junk food (perhaps because her life is so hectic she never has time for proper meals.) Liz also gets pretty violent when someone steals her food.
Jack also shows some stress-eating tendencies of his own, such as in the first season episode "The Baby Show," where Liz remarks to Josh that "Jack Donaghy is gonna kill me and then he’s gonna kill you and then he’s gonna fold us up in a pizza and eat us.”"
D.I. Peter Carlisle in the BBC miniseries Blackpool is almost always eating, unless he's unhappy.
Jayne Cobb seems to spend more time eating or looking for food than another crew member of Firefly, moreso in the feature film.
"He's always eating! That's why they're so poor."
He has, on at least one occasion, called dibs on food abandoned by other crew members.
"Hey, free soup!"
At least part of it is because the average food for space farers is protein paste. As soon as any fresh food becomes available, even Inara becomes a Big Eater. Also, Jayne is massively muscular and is called upon not only to fight, but to move heavy objects and the like, and is constantly training, so he's losing/using a lot of energy.
Steve from Full House. One episode even shows him grabbing food from the Tanner residence before his dinner date because he wants to "warm up".
Latka Gravas is sometimes featured as this in Taxi: Louie once asked the cabbies to take one chocolate from a box. Then Latka began to eat the entire box except for one chocolate. Louie then lampshaded this:
Louie: I said "take one".
Latka: I thought you said "leave one".
Latka's wife Simka also appears to be this, as Latka himself remarks that one thing he loves about her is that she eats like a pig.
In the pilot of CBS's The Flash, Barry Allen, much like his nephew in the comics, was explained to burn calories at a tremendous rate and was thereafter shown constantly inhaling food. In one episode he's shown stopping a crime at a banquet, and when the people he saved look around after he speeds out, they notice the turkey (Not cold cuts, the entire bird) is gone. The next scene shows The Flash finishing off a drumstick.
Brent and Lacey from Corner Gas. Brent even eats a bowl of perogies in under 5 seconds, and says it isn't his best time. He only took so long because Lacey fed him a big plate of chili cheese dogs before their eat-off in an attempt to fill him up.
Julius Nicholson from The Thick of It: "A man cannot live on Jaffa Cakes alone — I've tried".
Carly Corinthos Jax of General Hospital. Despite never being portrayed by an actress above a size four, Carly's love of junk — especially pizza and chips — is legend. In 2009, junk food nearly becomes its own character when Carly's perilous pregnancy forces her to go on an all health-food diet. References are made on a near daily basis about how her husband and sons are keeping her from her beloved crap, and when Carly finally goes into premature labor, it's while on a clandestine trip to score an order of fries from her favorite bar.
Alex Russo of Wizards of Waverly Place. Her parents run a sub shop, and she often takes customer's orders for herself, or finishes off their leftovers. She sometimes takes the dispensers from the tables in the shop and empties them directly into her mouth. She keeps an assortment of inappropriate food in her locker at school, including pizza, popcorn, milkshakes, whipped cream and maraschino cherries.
The West Wing: Ainsley Hayes — the trope namer for Blonde Republican Sex Kitten — likes to finish her statements with, "Are you going to finish that?" and a common Running Gag is her hunting for something to eat. That said, she doesn't eat as much as most people on this page.
Trick: Ueda Jiro, physics professor, ate a year's worth of rice in one day, then later in the episode (chronologically) ate a pot of rice that had been meant for over a dozen people.
On The Beverly Hillbillies, Jethro Bodine would eat any unguarded food (or what appeared to be food) in the kitchen. His typical breakfast was a large mixing bowl filled with Kellogg's corn flakes and milk.
Mike Stivic from All in the Family, much to the chagrin of Archie, whose fridge Mike is always raiding.
In an early episode of Glee, Will takes a distressed Finn to an all-you-can-eat restaurant where they can talk. One shot shows their plates side-by-side: Will's contains a moderate, healthy amount of meat and salad/vegetables, while Finn's, which is the same size, is piled high and overflowing with everything you can think of. It continues to be implied in later episodes that Finn is a Big Eater: Brittany points out that "You have sloppy joes for lunch every day and think you can get away with it," and being ravenous between meals is the reason he ends up dedicating a week of his life to a Grilled Cheesus. Which he eventually eats. When it is at least a week old and has travelled back and forth between home and school, unrefrigerated, who knows how many times...
We later also find out that Coach Beiste eats a whole rotisserie chicken at every meal - until she's burdened with the musical, student council elections, football etc, discovers that Breadstix delivers, and starts carbo-loading on enormous bowls of pasta. A damn' good trencherwoman, Shannon Beiste.
Pat Sajak and Vanna White really go out of their way to sample local cuisine whenever Wheel of Fortune tapes on location. This was even referenced on a Clip Show (the 4,000th nighttime episode), which showed footage of Pat and Vanna indulging while "Eat It" played.
Lindsay Messer on CSI NY sometimes. In one episode, Danny asks if he can get her something to eat while she's doing paperwork, and she asks for a whole list of stuff. Danny gets an Oh Crap look and she has to assure him she isn't pregnant again.
Veronica Mars: Wallace Fennel, though to be fair, he's a basketball player, and needs the energy:
Wallace: The day of the back-to-school athletics banquet there were spirit boxes in our lockers. There weren't any brownies in there, but there were cookies.
Veronica: Did you eat one?
Wallace: I ate six.
Veronica: That's my Wallace.
Leslie Knope in Parks and Recreation definitely qualifies. Leslie eats massive amount of junk food, especially waffles, sugar and whipped cream, while managing to stay pretty slender.
What boy on House of Anubis doesn't fall under this trope? It's most notable with Mick, Alfie and Eddie.
Even the actors acknowledged Mick's tendency to eat- his eating scenes are written in the script. Apparently the actor isn't much better, either.
With Alfie, not only does he always eat- he eats a lot. And it's rather messy, too. He's the one who once almost ditched Sibuna to eat Trudy's cookies instead while the students were under lock down and not allowed to eat anything Victor didn't allow them to.
Eddie is nearly as bad as Alfie is, though at least he can separate his duties from lunch time.
Kousuke Nitoh on Kamen Rider Wizard. He practically eats anything and usually uses mayonnaise to top his food, even on food that wouldn't make sense with it. His Phantom is an even bigger eater, consuming Phantoms whole. In fact, he requires Nitoh to feed him Phantoms, lest he eats him next.
LOST's Hurley is a compulsive eater and extremely overweight. Since the DHARMA products were discovered in season 2, he has been seen hoarding food and gorging himself at times. This was needed to Scotch Tape the common question of why Hurley was not losing any weight despite being stranded on an island (though some fans still ask it), but also added to the character's Back Story.
Friends: Monica Gellar was shown to be like this as a child, most likely related to her numerous compulsive tendencies. Her parents were even once shown asking her to eat excess Thanksgiving leftovers when they ran out of space in the fridge and the show presented this as a typical request.
One episode of CSI: Crime Scene Investigation dealt with a man whose brain did not process "full" signals from his stomach, and therefore constantly felt hungry. If he was not physically restrained, he would eat every morsel of food in the house and continue foraging for more. (He died of a ruptured stomach in the wake of an eating contest.)
Ron: Just give me all the bacon and eggs you have... Wait, wait. I worry what you just heard was, "Give me a lot of bacon and eggs." What I said was, "Give me all the bacon and eggs you have." Do you understand?
In fairness, this in Indianapolis after learning that his favorite steakhouse—which was the only reason he'd agreed to come to Indy in the first place—had closed. This was his equivalent of taking a freaking drink. While he had fully intended to get two gigantic steaks at the steakhouse, this is hardly as much as "all the bacon and eggs you have."
According to the book Pawnee: The Greatest Town in America, four times a week Ron eats a meal at JJ's Diner called the "Four Horse-Meals of the Egg-Pork-alypse", which consists of a 12-egg scramble, bacon, ham, sausage, hash browns, chicken-fried steak, and a huge stack of buttermilk pancakes.