Hollywood Thin

Mischa Barton still hasn't gotten much work lately. Casting directors probably think she needs to lose a few.

The opposite of Hollywood Pudgy. Basically, the media's tendency to present women far skinnier than the average person as attractive, healthy and average/normal.

If you were to take these people and compare them with a random selection of people, it would become obvious that many of them are much thinner than average. Often they will have an extremely small waist, very shallow ribcage and extremely narrow shoulders that very few women in the real world can possess.

Women considered "fit" enough to be shown on TV generally fall into the fifth percentile when it comes to shoulder width and rib cage depth. These are hereditary traits that no woman can actually control and that have nothing to do with actual physical fitness. Yet these women are the ones who Hollywood shows as "average", especially if they have unrealistically enormous breasts hanging just above that extremely narrow waist.

For men the opposite holds true. Any male who isn't sporting a six-pack, ripped pecs, or biceps as thick as oak trunks is often portrayed as, or is implied to be, scrawny and weak, even if the character is supposed to be fourteen years old. Again, if you were to take these guys and compare them with a random selection of men in the real world, their bodies would not be seen as very average looking.

Ditto in animation, video games, and a great many comics, doubly so because they aren't required to find living people who have the desired looks. In fact, being unconstrained by human physiology allows non-live-action media to take this trope Up to Eleven; see also Noodle People, Most Common Superpower and Heroic Build.

This is quite possibly a side effect of the entertainment industry's tendency to portray everyone as attractive, healthy, and average/normal except for when the plot demands otherwise.

Contrast Hollywood Pudgy and Hollywood Homely. Compare Informed Attractiveness.

Examples of Hollywood Thin include:

Anime & Manga

Any human or humanoid character (male or female) in any series by CLAMP. All are very tall (except for kids) and very thin. There's a reason why they're often called Noodle People.
Hiko Seijuro in Rurouni Kenshin. He spends a lot of time pumping iron to offset the side-effects of the Hiten-Mitsurugi Ryu, to the point where he has weights put into his trenchcoat. As a result, he has biceps the size of tree trunks, washboard abs, and huge pecs. Contrast this to his student, Kenshin, who does not spend as much time weight-training (and, while not flabby, is nowhere near as muscular as his teacher.)
The titular character of Nana. She's so thin as to be one of the Noodle People; one has to wonder how she got pregnant in the first place!
Clair Leonelli in Heat Guy J. The artist (Nobuteru Yuki) draws thin people to begin with, but really played it up with Clair. (It's especially noticeable with his dark clothes and sickly pale skin. Justified, as he's the resident Ill Boy in this anime. Averted in the manga, where he's still thin, but no more so than any other character, and not sickly looking.

Toys

Barbie is probably the most famous offender of this trope. Countless studies have been done trying to determine what she would look like if she were a real woman. They all say a wide variety of different things, but most come to a conclusion that can be summarized thus: "She would be extremely unhealthy, and her body type is ? virtually impossible for a real woman to attain." To be exact, they said that she would be unhealthily thin, six feet tall in her bare feet, have feet too small to walk with, and have a long, serpentine neck. This is a good image showing just how ridiculous Barbie's proportions really are.
The male counterpart would be newer G.I. Joe figures. If blown up to full size, they would have roughly 25-inch biceps. For comparison, jacked-as-all-hell Mark McGwire had about 22 inches at his peak.
Bratz are this, creepily this.

Live-Action TV

Many, many shows, including...

Ally McBeal was this trope at its extreme. Portia DeRossi has recently come out about her anorexia issues stemming from the show. Callista Flockhart was no fatty either...
Lost, which does this for both men and women (with the exception of Hurley).
House. Particularly Thirteen (Hugh Laurie is skinny—which given the fact he had been a rower at Cambridge makes sense—but any perception of sexiness arises out of his scruffy beard and big Blue Eyes).
The new V series. Justified for the Visitors. For the humans, not so much.
Averted on Mike and Molly. Molly's sister, who is portrayed as the hottie, looks to be about a size 12 (US).
America's Next Top Model. All of them. Even the contestants portrayed as "big" or "full figured" are ~~underweight.~~ fantastically curvy but nowhere near fat.
Actually subverted in the makeover show The Swan, of all places. Contestant Kelly Becker from season 1 was the only girl who had to put on weight during her training as the judges felt she was dangerously underweight. She put on some muscle and looked much healthier by the end.
Nicely subverted in Ringer, as former prostitute and drug addict Bridget attempts to assume her healthier twin sister's identity, and everyone comments on how much thinner she is, which they largely don't see as a good thing. Of course it is still Sarah Michelle Gellar that they're talking about.

Film

Averted in The Machinist - Christian Bale's character Trevor Reznic is described as "if [he] were any thinner [he] wouldn't exist", and it's true - Bale lost an incredible amount of weight to play the role, eating very little. Then he had to bulk up again for Batman Begins, wherein he was around 220.

Music

During his "Thin White Duke" period in the mid-1970s (i.e. Station to Station), David Bowie dropped in weight to 94 pounds as a result of his diet of "red peppers, milk, and cocaine." Let us repeat: 94 pounds. Not 194. Not 94 kilograms. 94 pounds. And no, Bowie is not short: he's 5'10", which is slightly taller than the average British man of his generation.

Professional Wrestling

One episode of Raw had Randy Orton return from injury and Vince McMahon came out and said his clothes looked like they were hanging off him and his neck looked like a stack of quarters (implying he'd lost weight because he hadn't been able to train due to his injury). Except Randy looked exactly the same as he normally does.
The Smackdown writers deserve to be slapped for having Michelle McCool call Maria Kanellis "underfed" when A) Maria has said she was told by management that she was too fat and B) Michelle has a thinner body size and has struggled with anorexia in the past.
- The Lay Cool characters are probably a subtle Take That to this trope as one promo had Natalya insult them by saying their IQ was lower than their combined (non-existent) waist size and of course you have the heels in the situation as two fashion-crazy Valley Girls obsessed with their weight.
A lot of people tend to go on about how the WWE Divas are too skinny but it was quite a shock when Maria Menunous got in the ring and she looked like a skeleton next to Alicia Fox, Rosa Mendes, Gail Kim and Kelly Kelly. Though the difference is obviously down to the divas being actual athletes and having muscle on them even if it's not too visible.

Webcomics

Ciem is the closest to this that Machinomics are capable of committing. Almost every female character uses the same custom "Barbie" mesh (Zenman's Curvy Default Replacement at Mod The Sims, with size B breasts.) Candi herself is extremely prone to narrowly avoiding being the poster girl for Hollywood Thin, especially as a teen. Her sisters, however, are implied to be slightly curvier with their clothes off; though there is little evidence in the written canon. Then again, since her sisters aren't superheroes, their being thinner is tolerated, if not actually justified: not having Candi's job gives them an excuse to be laz y(-ier).

Western Animation

All women in the show Tripping the Rift. All of them, human and alien alike, have wasp waists and massive racks.
Clever show that it was, Sabrina the Animated Series featured a character design for the girls that was just unsettling as far as their skin-and-bones stature was concerned.
The girls in Winx Club. Especially in their fairy forms. (Kinda justified for the main characters and their magical friends. With their magical insect wings, it doesn't seem so strange that they have an insect-like body structure. Not justified for the muggles, however.)
- Oddly enough, they look fairly sized, even if on the small side, as children.
Nearly every female character in Danny Phantom has a small waist, generous rear end, and curvy legs. Even the dead ones. And his middle-aged mom.
Same goes for Fairly Oddparents. They are the Trope Namer for Hartman Hips.
Taken to the extreme in The Simpsons. In the episode "Sleeping With The Enemy," we see a child model who weights so little she's reputed to have gone back to her birth weight, and becomes too thin to see should one look at her from the side.

Fashion

Tabloids. Just... tabloids. Pick one up at random and you'll see a Shocking Exposé of some star's Embarrassing Body Flab or Cellulite, accompanied by ancient stock swimsuit pics. Anyone with ten pounds of extra fat or more is considered "struggling with weight problems."
- Tabloids are really inconsistent about it, too. The cover will show a Hollywood Thin girl with the appropriate headlines (Deathly skinny! Only 94 Pounds! Family is Scared for her Life!). However, open it up and five pages later it will talk about her looking "Fabulous in a [HARD TO PRONOUNCE DESIGNER] gown at a party last week."
- It's also not unusual to see a hand-wringing "How Thin is Too Thin" tabloid that contains pages of advertisements for questionable (and dangerous) diet pills that promise you'll lose twenty pounds in two weeks. In some cases, the woman (and it's usually a woman) in the "before" picture looked a little bit fleshy at the most and in the "after" shot, she looked Hollywood Thin.
- More insidiously, the "BABY BUMP??!??!!" articles/headlines often serve the same purpose, except that instead of directly shaming an actress for daring not to be Hollywood Thin, they purport to be excited about her suspected baby. Even if the suspected "baby bump" is no more than a loose T-shirt or an actress daring not to have a perfectly flat washboard stomach.
Fashion photography has reached the point, in its ever-stricter search for vanishing thinness, where the models are starting to look like death warmed over. So, the visible ribs, the bags under the eyes, the other signs of starvation are photoshopped away, though, of course, the model remains as twig-thin as she was at the start. Readers are led to assume that this kind of body shape can be attained without looking like a walking corpse, and the search for a model who actually looks like Gumby goes onward.
Worth noting is the recent controversy over 2011's London Fashion Week, which used models that were obviously very unhealthy. Say all you want about some people being naturally thin, but that sure as hell ain't natural!
Closely related... shop mannequins generally have Barbie-like implausible figures, being tall and sylph like. To make the mannequins look even thinner, the stores will put them in the smallest possible size, then pull the excess fabric to the back and tie it there so that the mannequin's inhuman figure can be displayed in full.
The aptly named model Twiggy is widely regarded as having first popularized the idea of thin women as sexy, moving away from the "curvy is sexy" image of the early 20th century.
- There were allegations that she was anorexic, despite the fact she was noted for being a Big Eater. That doesn't rule out bulimia, though.
  - Contrary to popular belief, only a small fraction of bulimics are underweight; the majority are average or overweight. There is purge-type anorexia, however, which does present with excess weight loss. If she did have an eating disorder and was severely underweight, it would be classified as anorexia.
- It could have also been an endocrine disorder. If your metabolism is stuck in overdrive, you can easily burn 4,000 calories per day doing nothing.
- Twiggy, herself, observed in interviews at the time that "obviously" no other models would be so freakishly thin in the future.
It has been repeatedly shown in studies that Hollywood Thin is the least health weight category of all (it is far less risky to be among the most morbid of morbidly obese). The lack of body weight causes undue stress on internal organs and means your body has no reserves to fight infection or repair from injury.
Thankfully, this trope may be on its way to become discredited as many Fashion industries impose a minimum weight limit. They're beginning to realize having models that fit their definition of beautiful isn't much good if they're too unhealthy to get on the catwalk.