In Real Life, a person's physique, if not their physical size, is generally a dependable indicator of their physical strength. Muscle strength (force applied in Newtons) is proportional to the 'physiological cross-sectional area' (PCSA) or the total number of fascicles of the muscle.note Per cross sectional unit area, healthy human muscle produces the same amount of force with little deviation, regardless of whether or not the muscle has been trained and factors such as age and gender. All things being equal, more muscle translates to more strength.
In fiction, all bets are off. Muscles? Who needs 'em?
The Pintsized Powerhouse is able to physically outperform heavily-muscled guys ten times his size, and is more than capable of sending them flying with a single punch, physics be damned. A thin, wiry character may have no difficulty lifting or punching way above his weight class. This is generally done to show just how Bad Ass he or she really is. Usually lampshaded by Super Strength, and often more dubiously by a Charles Atlas Superpower. Alternatively, The Big Guy may not be very strong at all, but usually his strength is simply dwarfed in comparison. The Big Guy being physically dominated is usually a Giant Mook or similarly unimportant character. Generally, when it comes to important Big Guys, Muscles Are Meaningful.
Weaker characters beating the stronger characters is often a demonstration of the fact that skill and other factors can trump strength in a fight, which is Truth in Television to a certain degree, but not really an example of this trope.
There are several related tropes:
Mind over Matter. A psychic uses telekinesis to augment his own physical strength.
Glass Cannon: A more realistic take on this trope. A character may have insane offensive skills due to their strength and maybe speed/agility/reflex, but their lack of muscle doesn't favor the character defensively once hit.
Dragon Ball, of course. Soon justified by ki energy, but even before that, Goku could destroy rocks as a child when he was still the size of a watermelon and had stubby arms like a baby.
This actually addressed as a plot point in the Cell Saga. Vegeta and Future Trunks had reached a certain ascended version of the basic Super Saiyan, but while it was an insane increase of power, the sheer muscle mass slowed them down too much to actually land a blow on their opponent.
There's also very early on the contrast between Vegeta and Nappa. Nappa, who's huge and brawny appearence was used to emphasize his power and dominance over a 4ft tall man and a child not even six. Naturally, he beats them both with ease. However, as giant as Nappa is, he is less than half as strong as the short, then scrawny Vegeta, and is later evenly matched by Goku, who while buff, is only half to one third his size.
Probably the most striking example, though, is Mr. Satan, who's legitimately strong, extremely muscular, and has a Badass Mustache, but happens to be in a series where ki power beats muscle power ten times out of ten.
Videl is actually one of the straightest examples of this, as even before she learned basic ki manipulation she was at least as strong as her father Mr. Satan, despite being a slender teenage girl with none of his huge muscles. As for why Gohan doesn't accidentally snap her in half, it's probably for the same reason real-life weightlifting champions can pet a kitten or pick up an egg without crushing it. Controlling your strength to use only the amount you want to for the task at hand is not difficult.
Bills from "Battle Of The Gods" has very little muscle mass and looks like a sickly purple humanoid spinx cat and he's the most powerful being in the universe.
Pan is just 4 years old when she competes in her first martial arts tournament, and she's sent up against a very muscular man. She defeats him easily, so easily that it freaks Uub out (who, unbeknownst to him, is vastly stronger than Pan).
Most of the Dragon Ball adult male fighters though, are actually very bulky and muscular. Any more bulky and they would be the Giant.
The complete dependency on Shinsoo in Tower of God. It is the one thing defining power and muscle mass really means absolutely nothing. Not only does the Square/Cube Law come into effect, but being big is an entirely different problem when in some areas of the Tower the Shinsoo, which acts as air surrogate, is as dense a 4°C water. Thus character with high Shinsoo resistance and control like Baam and Yuri have a huge advantage.
Yuri and her clan, the Ha, is also a traditional case of being physically very strong while having a fairly feminine frame. Other characters, especially the damage dealing Fishermen can strengthen their body temporarily while inducing Shinsoo into their body.
The CP9 of One Piece have the huge guy Blueno, but he's one of the weaker ones. By far the most powerful in the team is the lean (though tall) and attractive Knight Templar Rob Lucci. And then there is, of course, Luffy himself, who is one of the strongest people alive and has arms like sticks. Funnily enough, there was at least one occasion where he flexed his arms to reveal muscles larger than his head.
Luffy's small arms are justified since he is made of rubber. Zoro, on the other hand, is just plain crazy. When he flexes, his arms become the size of his torso. When relaxed they are normal size. On the other hand, Sanji's kicks can smash down buildings but he's pretty consistently a bean pole.
The same also applies to the admirals, Kizaru being the most prominent example; they are among the most powerful of antagonists, but all three are very thin for their height.
In the case of Kizaru, however, there's a justification for this. He can move at the speed of light — with that sort of power you're always going to hit hard regardless of how much muscle you have, if only due to sheer speed.
Before Alvida ate her Devil Fruit she had decent Stout Strength (being able to wield a large iron club), but she's still strong after eating even though it made her much skinnier (and more attractive).
Also, Robin is a tall, slight woman with the strength of an above-average athlete, which is pretty weak compared to some of the monsters of the series. However, she easily makes up for it with her Devil Fruit ability, which allows her to break your back effortlessly.
Robin: Power. Speed. Against me, they mean nothing.
The introduction of Amazon Lily featured a refreshing subversion. A slender, beautiful woman duels a gorilla-sized lady-gonk in hand-to-hand combat. The gorilla beats the snot out of her lithe opponent.
YuYu Hakusho deals with this a lot. In one of the first arcs, it's specifically shown that physical strength is different (and weaker) than spiritual strength. If you see someone who is muscular in a fight, chances are he'll be relatively weak (with the exception of Younger Toguro). Particularly addressed in the final Tournament fight, when Yusuke reveals his Spirit Cuffs, and the flashback to when he got them shows him trying to tear them apart, to no avail. Genkai comments that it measures spiritual energy, NOT physical, so knock it off.
In another sense, as various characters get stronger they don't gain much in physical size; they retain the same basic body style that they start the show with.
Hunter × Hunter (by the same Mangaka) has even more fun with this- the two Kid Hero protagonists are skinny 12-year-olds- and at the start of the series, Killua can bench somewhere in the range of 16 tonnes. A later chapter gleefully lampshades this- the two of them decide to go work out to keep their edge. The next panel has them waving around barbells with weights larger than their entire bodies in a rather offhanded manner while casually conversing about their current job, as a gymful of goggle-eyed bodybuilders looks on.
In Fruits Basket, both Yuki and Kyo are skinny bishounens... but they have the strength to practically kill each other and destroy Shigure's house. Also, Kagura is an innocent-looking girl, but can rip out trees by their trunks and swing them around as weapons.
Natsuki Takaya (the artist) actually acknowledges this in an aside from the manga: by all rights, the characters should be more muscular-looking than they are, and it's mainly a design preference that they're not (skinny bishounen and cute girls). In addition, Kagura likely derives her inhuman strength from somewhere else.
Bleach: Used many times due to the fact the characters use spiritual energy to fight. As a result, size can be meaningless in the face of who has the most spiritual power and the most skill to maximise their spiritual power. This can be seen in the zanpakutou and the Menos Grande. A shinigami zanpakutou can look like a completely normal sword but it's sealing enormous power and therefore cannot be used to gauge the strength of the shinigami that wields it. The weakest class of Menos Grande is the Gillian. It's also the biggest type of hollow that can be found. The strongest is the Vasto Lorde, which is no bigger than the average human.
The most dramatic example is Yammy, the 10th Espada. He is physically the largest Espada and can keep getting bigger. As 0th Espada, he's by far the most powerful, too. However, he lacks the skill to apply his power, something that's heavily lampshaded in the manga. As a result, when he fights a captain tag-team while in his largest and most powerful form, the captains, who do know how to use skill to harness their power, curb-stomp him.
This is all over the place in the Tournament Arc of Mahou Sensei Negima!. Just of the eight of eighty we see get through the qualifying royales seven of them are either a slender young woman, a child, or both (physically, at least), and the other one that was an adult male wasn't at all buff. All of them completely trash all but one of the other divisions, which consisted of eighteen other people which were nearly entirely heavily muscled (if not flat-out gigantic) adult men. Many of them weren't even using any special powers like ki or magic. Anyone of above-average size or build who isn't Jack Rakan exists solely to get their ass kicked by someone skinnier and more attractive for the sake of said person looking cool.
Present in Fushigi Yuugi. Even with all the superpowered warriors, there isn't a single highly muscular character. What else would you expect from a shoujo Reverse Harem anime?
A specific case of this is Nuriko, whose power is super strength, yet he's skinny enough to convincingly crossdress as a woman.
Kyohei and Sunako from The Wallflower. Both are very waifish, and both can easily beat down crowds of enemies when they need to.
L from Death Note, who is 5'8" and weighs 110 lbs, is quite strong, and fights using capoeira. He even states at one point in the series, while in a serious fight with Light Yagami, that he is stronger than he looks.
Soul Eater uses the combination of a healthy 'mind, body, and soul' to define strength and point out that it's not purely down to physical power. Characters who are shown to be extremely strong physically do not always appear as such; Maka and Kid for example, though the latter has the excuse of being a god. It doesn't hurt to be muscular, however, as characters like Black Star (especially) and Stein show.
Averted when Maka and Black Star (who while muscular, is still just a child) take on Free, a werewolf. A big and muscular adult male, Free dominated them in battle, despite the fact that he had been rusty after being imprisoned for 800 years.
Averted with Crona and his symbiotic weapon, Ragnarok. When they first appear, they are unbeatable for Maka and Soul, and Ragnarok's huge muscles and large size certainly helped him and Crona in battle. Later the two fight Kid and seem evenly matched with him, which is actually quite impressive, as Kid is a god and the son of Lord Death, a shinigami.
Also, when Ragnarok loses his great muscle mass when his soul is cleansed, he and Crona are noticeably weaker, but still not to underestimated.
Inuyasha is pretty trim under that kimono, but he can uproot large trees and use them as weapons, pick up and carry a bolder larger than he is tall, etc. Even for a hanyo, InuYasha is incredibly strong, stronger than many full Youkai.
His brother Sesshomaru counts as well. The very first thing we see Sesh pull in the manga is placing his hand lightly on a big, muscular man's head... and ripping it clean off without even a hint of effort. He's not any less muscular than Inuyasha (both of them do have some muscle tone, which is more than can be said of many Bishōnen), but he isn't any more so, either. Word of God states that Sesshoumaru's one arm strength alone is equal to Inuyasha's whole strengh.
Somewhat averted, somewhat played with in Naruto. While some characters use special chakra-based abilities to have Super Strength (just look at Sakura and her teacher, Tsunade (whose trademark ability is her raw strength). Barely a muscle on their slim bodies (except for their bosoms), but they can beat down mooks fifty times their size!), the characters known for being physically strong are usually HUGE. A, Killer Bee, and Chouji come to mind. There ARE exceptions, like Rock Lee (who is much stronger than his muscles would suggest, and DOESN'T use chakra to make up for it).
However, in one of the first filler episodes Sakura rips up a ship's mast and uses it to beat the bad guys off the vessel. This is before she began her training with Tsunade, you understand. It was a big ship.
Tsunade, due to being a hybrid of a Senju and a Uzumaki (both clans with massive amount of pure physical ability and vitality) has incredibly high natural physical strength. So much so that without chakra she could lift and wield Gamabunta's sword after being seriously worn out...and when she enhances her strength with chakra she can bust through Madara'sSusano'o.
Kenichi: The Mightiest Disciple has Master Koetsuji Akisame. He's the smallest and skinniest of the masters (The other male's are all about 8' tall and have muscles the size of their heads) and just looks pretty fit. He's actually one of the flat out strongest masters due to the fact that he spent most of his life completely remodeling his body so that he has absolutely no wasted mass on him. Kenichi himself is going through similar training. He looks like a pretty fit teenager, who just so happens to be described as feeling like he's made out of lead and doing such feats as stopping a giant boulder and doing a handstand while in a leglog from a much beefier opponent.
Averted by Badass Grandpa Master Hayato; He's the biggest, tallest and most muscular of all the masters, and actually is strongest of all the masters, not to mention the most skilled.
Akisame is only the smallest and skinniest if you somehow COMPLETELY ignored Kensei Ma, who's a much truer example of this trope. The man is probably barely 4 feet and is the eldest of the masters (barring the Old Master Hayato himself), making him very scrawny. He seems to be of the Weak, but Skilled category, but he's capable of delivering devastating punches at close range, with apparently barely any technique involved.
Kenichi isn't really an example. He's only average looking at first glance, look closer and you'll see he is quite muscular, although he lacks the sheer bulk of some of his masters. Most of the time this isn't apparent since his clothes cover his muscles.
Of course, Saint Seiya has this in spades. Cassios and Docrates, two enormous towers of sheer muscle (Shaina's disciple and one of the Pope's acolytes, respectively) are humbled by skinny 15 year-olds Seiya and Hyoga. Most noticeable in that Cassios' fist is as large as Seiya himself, but the latter can easily stop Cassios' punch with his open palm. Without even using his Cosmo (or leverage, for that matter.)
The Prince of Tennis: Toyama Kintaro was twelve years old, not even five feet tall... and was able to drive a golf ball farther than a college student with a 5-iron that he bent with his bare hands.
Who's the strongest character in Durarara!!? Is it Simon, the huge black Russian sushi tout known to be capable of lifting men his size with one hand? Nope, it's Shizuo the skinny, blonde ex-bartender. A skinny, blonde ex-bartender that can throw vending machines four stories high. This is due to the fact that, beyond lacking the mental limiters most people have to keep them from ripping their body apart via overexertion, most of Shizuo's muscular structure is so dense and compact that most bladed weapons have trouble penetrating it beyond a centimeter.
It's stated in the anime that Simon is better that Shizuo in a one on one fight. He's the only one who can stop Shizuo's rampages, albeit with some trouble; he does it and comes out with some bruises and a black eye. Shizuo is stated to be better in a street fight however, due to an advantage in speed and his nigh invulnerability.
His body is THAT awesome because he literally broke every single bone in his body multiple times in his youth, due to the super strength and Hair-Trigger Temper. After breaking so many times, his bones won't break anymore. On top of that, his pain receptors broke down from overburdening, and he feels no pain. In one of the last episodes, he got shot in the back and in the hip from behind, and thought he slipped in the mud. When he realized what happened, he got up and walked halfway across Ikebukuro to Shinra's house to have the bullets removed.
Pokémon Special: Bruno of the Kanto Elite Four is a muscled powerhouse who trains alongside his Pokémon, always searches for the next big fight (Lorelei interferes when he faces Red, much to his chagrin before he gets brainwashed), and poses the Kanto Dex Holders no end of trouble. His disciple, Hoenn's Brawly, looks to have half the muscle he does, but has the same level of strength, which he pools with his determination to outmuscle Mack's Mind Rape when Groudon goes on a Magma-assisted rampage in Mossdeep.
On the subject of Gym Leaders, Chuck and Bruno are on the big end, the former knowing a vast array of martial arts and takes up the same Fighting Gym Leader habit of training with his Pokémon. In case you think he sucks as a teacher, one of his disciples is Green, who while not demonstrating his talents in martial arts on-panel is hardly a slouch at commanding Pokémon. And if Brawly wasn't "scrawny" enough, then Maylene of Sinnoh manages to top that, being a skinny teenaged Pettanko who can cross blows with a Riolu - which, as we know, grows into Lucario, which is (literally) Made of Iron. This troper sees bad things happening to Team Galactic should she have to get involved.
Many of the Dex Holders themselves manage to perform feats of physical excellence, but the majority of them are a result of being drunk on Heroic Resolve. And then there's Sapphire, whose feats of strength and heroism speakforthemselves.
Hell, even Blue may be stronger than she appears. At age 11, she once held onto her flying Jigglypuff with one hand while the other arm was hoisting up Red.
Hareta from Pokémon: Diamond and Pearl Adventure is absurdly powerful for a kid his age but has no muscles (probably considering he's prepubescent). At one point he flipped a Rhyperior, which is over 600 pounds and a rock Pokemon.
In Pretty Face, Rando was in a coma for a year and his muscles shrank for not using them. Strangely enough, despite this, his physical strength didn't go down at all.
The strongest characters in AIKI are pretty muscular... but only on the middle of the size scale. The strongest women barely have any. The trope itself is invoked when Joukyuu informs Hou Mei of why she's doing badly in a fight against an opponent who's much smaller - she's too muscular and it's slowing her down. She leaves for a time to train, returning noticeably slimmer and much faster.
Played straight twice in Shaman King, first with the characters itself. Being a big guy in Shaman King is meaningless since power in the series is all about Mind over Matter, or more precisely soul over matter. Secondly with the spirit powers itself. During most of the series, when a character gained a power-up, they would start to summon building-sized spirit Battle Aura called O.S.. Then during the final part of the series, the Big Bad says that making those gigantic things was pure waste of power. In the end they fight with much more powerful, yet much smaller O.S.-es.
The mages in the Magical Girl Lyrical Nanoha universe are extremely strong physically, but it doesn't show much in their physique. In the beginning of season two, the nine-year old Nanoha protected herself from attacks from both sides, holding the shields apart with her bare hands in a Star Wars-like double-Advancing Wall of Doom manner. Both attacks had the momentum to blow a hole in an average building and eventually made Nanoha sink ankle-deep into the concrete floor. And that's a nine-year old girl with no excessive muscle mass. Powerhouses like Signum could probably punch holes in reinforced concrete with just those sleek, sexy hands of theirs. (This probably has to do with the series' target demographic, which prefers cute girls to muscular warriors.)
Claymore has this in spades. All Claymore warriors are lithe killing machines powered by Yoma blood inside them. The only exception is Undine, but it is revealed that she built up the muscle mass on purpose in attempt to improve her own self-confidence. In the flashbacks, she is shown with her original, (seemingly) frail constitution.
Justified: she's the daughter of Superman and Wonder Woman. No, really.
Yakitate!! Japan's Azuma Kazuma, he may not be as muscular as his other two teammates (Kawachi and Suwabara). But his bread baking skills beat his opponents into submission.
Rurouni Kenshin: We have Sanosuke, a lean hand-to-hand combat fighter. Yet he's strong enough to lift a heavy zanbato and clash with muscular monk Anji. Anti-hero Saito, who can beat Sanosuke into a bloody pulp, and Shishio, who has enough power to send Sanosuke flying, are also quite slender.
Averted with Seijuro Hiko, Kenshin's master, who seems a tall and slender man... until he takes off his coat, revealing a huge muscled body. Word of God says that some fangirls were disappointed at him not being a Bishounen.
It's also deconstructed with Kenshin himself, who's a small slender man unlike Hiko, and thus not really suited for his style of fighting at all. By the end of the series he's unable to fight as well as he once was because of the strain on his body.
In Ranma ˝, the only two characters who have really visible muscle are Genma Saotome (who is not only a Dirty Coward, but actually comes off as Stout Strength and Acrofatic because his muscles and baggy gi make him pretty barrel-shaped) and Pantyhose Taro... the latter only when he takes on his Mix-and-Match Critterssuper-form (which, admittedly, outclasses everyone that isn't an Old Master.) Everyone else is capable of fits of Super Strength while being, at most, leanly toned looking. Even Ryoga, while thicker-chested then Ranma, still looks pretty scrawny with just a T-shirt on.
Averted humorously in Stand Alone Complex when Batou, jokingly, tells the Major she should switch to a male prosthetic body like his because it would give her more strength. She challenges him on the spot and he brings his fists up ready to spar. She hacks his brain and makes him punch himself out, proving she doesn't need more strength when she has her far more effective brain.
In Rosario + Vampire, Inner Moka is capable of taking down opponents that are larger and more muscular than her with ease. Her sister Kokoa can lift and swing a huge mace seemingly without any effort. Justified as it is a vampire's special ability: they can turn their Yoki, which is already pretty high being S-Class Youkai and all, into physical strength.
Black Lagoon: Dutch, the Lagoon Company's leader, is a fairly muscular guy but gets easily overpowered by the thinner Roberta. Ultimately, the much more trim Revy is the only match for her.
Just about every single Shoujo that involves action, including the male characters and even in series that don't have the supernatural excuse. You can be a pretty boy and still have a good amount of muscle but not in shoujo.
In Fairy Tail, size and muscle mass is hardly ever an indicator of strength, barring a few exceptions like Gildarts. The incredibly thin Sol was able to overpower Elfman with ease, and so could Mirajane.
While the more powerful martial artists in Fist of the North Star are muscular men, they can easily tear apart King Kong sized thugs who are even more muscular than them; Kenshiro didn't even break a sweat killing off the much taller and buffer Zeed.
Shizuka Fujiyama, head engineer of the Daiku Maryu in Gaiking: Legend of Daiku Maryu, has no apparent musculature whatsoever, yet is able to very easily lift at least three of the incredibly heavy metal plates that the other members struggle to even lift one of.
Batgirl is noted in the comics as being far stronger (and faster) than even a highly athletic girl her size should be. This is mostly down to her training.
Averted with some super-strong heroines; She-Hulk and Power Girl (to name two) are typically drawn with a body-builder's level of muscularity, being among the rare believers in the idea that just because you already have super-strength doesn't mean you can't benefit from pumping some iron to get even stronger.
But much like Wonder Woman, it depends on the artist. There are times She-Hulk is drawn without muscles.
Spider-Man possesses incredible strength but also possesses a thin physique that earned him the nickname "Puny Parker".
This highlights Sam's power in iFight Crime With Victorious - having her power prevents her from gaining extra muscle mass. Ricky Flame on the other hand can, and exercises regularly to increase his superhuman strength.
John qualifies when he's wearing his illusion cloak, which makes him look like his normal skinny Earth self.
Millers Crossing: The Bruiser of a Mook duo rolls up his sleeves to administer a warning beatdown on Tom, giving him a sporting chance to remove his own coat. Tom uses that chance to swing a chair into the bruiser's face. The bruiser whimpers and waddles from the room, pathetically nursing a bloody nose. A second later, the tiny old man slams open the door, speed-marches toward Tom, and his fist hardly fills the screen before blackout.
Morpheus: Do you believe that my being stronger or faster has anything to do with my muscles in this place?
Neo:(shakes his head)
Morpheus: You think that's air you're breathing now?
The second live action Transformers movie has Optimus Prime dominating Megatron in battle, despite Prime being smaller and getting beat up by the latter in the first film. Justified in that Prime was distracted by his fear of collateral damage in the first film, whereas he can cut loose with no problems in the second.
In Kung Fu Panda, all of the Furious Five seem to have about the same amount of strength. It seems semi-plausible (Tigress is the biggest and seems to be the strongest), until you get to Mantis, who is an actual praying mantis. He has no problem throwing Po around or holding up the rope bridge that all the others plusTai Lung are fighting on.
In How to Train Your Dragon, Astrid doesn't seem to have much muscle mass at all, and yet she can still hurl giant hammers with enough force to knock out dragons.
Justified for force users in Star Wars in that the force is much more powerful than mere physical strength and can even enhance it,which means that both Jedi and Sith don't need to be extremely fit in order to defeat an opponent twice their size or lift heavy objects that would crush a normal person.
In The Guardian, a movie about the US Coast Guard's rescue swimmers, one of the candidates is extremely well built and is washed out on the first day due to cramping up during a swim. Kevin Costner's character dismisses him with a comment that muscle doesn't float.
In Tangled, Rapunzel can haul a grown woman up the height of the tower, without so much as a pulley, and inflict serious damage with her frying pan. And remains a slight little waif.
Lampshaded and subverted in Robert Asprin's Myth Adventures - Guido is getting the "size doesn't matter in a fight" lecture from a drill sergeant, and muses that this only works if the little guy is very skillful while the big guy is very UN-skillful. He then proceeds to break the arm of the drill instructor, who had been planning to use him as a tackle dummy.
In Power of Two (part of the "Fine Structure" series at Things Of Interest), it's noted that people who get superpowers don't look any different, and the narrator muses that "We don't even know if you gain anything from working out when you have these abilities".
Justified in Codex Alera by Earth crafting, which is explicitly noted to provide strength but not extra mass, and Air crafting (though if it isn't backed up by Required Secondary Powers it can be quite painful) which provides speed, meaning one can make like the Flash.
Sherlock Holmes is tall and wiry, but he is also extremely strong. After a burly man threatens him in "The Speckled Band" by bending an iron poker, Holmes casually straightens it.
Ditto Erast Fandorin. Except that he has the justifying bonus of having been trained in ninjutsu for six years, meaning he can kill pretty much anything with his bare hands while hiding his strength under frail, bishie looks..
Redwall: Continuity Drift makes it hard to tell whether the animal characters are supposed to be human-sized, animal-sized, or somewhere in between, but it's pretty clear that animals which are smaller in the real world tend to be at least a little smaller within the canon than animals which are larger in the real world. It seems to be a rule that the small cute animals are the good guys and therefore more likely to win in any given fight. Mice versus rats is okay, but when a squirrel can fight a wolverine to a standstill it looks a tad odd.
The size difference between animals appears to have decreased between books. The original had Cluny vs. Matthias and Cluny was far larger, and Constance was even bigger than he was, indicating a roughly accurate size difference that continued through the early books. About halfway through the series or so the difference seems to have changed from a normal person fighting a T. Rex to a smallish person fighting a tiger or something. Actual physical strength doesn't appear to be different except in extreme cases like badgers etc.
Elves and Riders in the Inheritance Cycle are often capable of feats of strength (and speed and magic too) beyond that of most humans, including humans with way bigger muscles. Eragon himself notes this in Brisingr by comparing his muscles to his cousin Roran's much larger muscles.
Pippi Longstocking is perhaps the most famous example of this trope in literature. She can lift one of the area's strongest men... when the man is lifting 100-lb weights, and Pippi herself, as the article's image shows, has ridiculously skinny limbs.
Her dad has Stout Strength, and when they meet they throw each other up in the air. When they playfully test each other in Pippi Goes on Board they're about even.
This trope is also used in the Dragaera novels. Dragaerans average about a foot taller than normal humans (or "Easterners", as they call them) and are stronger in spite of rarely having visibly muscular builds.
First played straight in Graceling, as Katsa's extreme talent, flexibility, and speed make her too Bad Ass for strength to matter much, but subverted once she meets another Graced fighter (though of course Po's Grace is a bit more complex than that) and realizes her size and relative weakness do disadvantage her.
The Doctor, in the Doctor WhoEighth Doctor Adventures, can easily carry a grown man around, has threatened one of his companions with the fact he could break any bone in said companion's body (he was really stressed out at the time), and once stabbed a guy with his thumb. He's 5'8", "slight", and "bony".
'Except that it took someone very strong to kill Macleb,' Cage said. 'To me that means a Canvine.'
The Doctor shook his head. 'Not necessarily.'
The Doctor turned and looked her dead in the eye. 'Would you say I'm very strong?' he asked.
This seemed to amuse her. 'Not really.'
But the Doctor was serious. 'Strange,' he said quietly, 'because I could break you in half as easy as sneeze.'
There was silence for a moment. Awkward silence.
The Seventh Doctor in the Doctor Who New Adventures, while not being as physically active as his older counterpart, is often described as having an uncanny strength, and the grip of a bear, when need be. He's 5'6" and of a small build.
Sisterhood Series by Fern Michaels: Yoko Akia. She is 4 feet 8 inches (1.46304 metres) tall, she weighs 90 pounds (40.82 kilograms), and just about everything about her is tiny. She can flatten just about anybody bigger, more muscular and weightier than her in a fight and her fellow Sisters and Vigilantes call her "the 90-pound stick of dynamite"! In the book Lethal Justice, Yoko (who supposedly has a brown belt) spars against Harry Wong, who is likely a Bruce LeeExpy, has a black belt, is bigger than her, has more muscle than her, and could supposedly flatten her without difficulty. Instead, the little "porcelain doll" (as Harry described her) ended up pinning him to the ground. Harry afterwards admits to Jack Emery that that was the first time he was ever pinned to the ground!
Mistborn, those who can burn pewter gain Super Strength but no muscle mass, Vin, a 5 foot nothing skinny girl can beat the living crap out of several large men at once when burning pewter.
Though also partially Averted: a naturally strong man burning pewter is still stronger than a naturally weak man who's also burning pewter.
And totally Averted with Feruchemists, who actually get more muscles when they tap Strength.
Stated in The Kingkiller Chronicle with the matriarchal Adem culture of warrior-philosophers. The hero's female mentor states that women are better fighters then men because they are more moral and therefore understand their fighting style better. The hero asks about men's superior reach and strength, which the mentor dismisses as irrelevant. Since Adem are far and away the most skilled warriors in the world, their views are apparently justified.
In A Song of Ice and Fire, Loras Tyrell is still a teenager and frequently described as slender and feminine in appearance, yet he's one of the best fighters in the Seven Kingdoms and is seen kicking ass with full plate and battleaxe in one scene. He is, however, defeated by a larger, stronger fighter. (Although said opponent was psychotic enough to decapitate his own horse in a rage, so that was definitely a factor.)
A more realistic example than some series. Leaner combatants can get by through skill or speed, but never or rarely overpower the larger fighters. No one has ever overpowered Ser Gregor Clegane, for example. But a lean warrior such as Oberyn could certaintly outmaneuver him into a killing blow.
Dorina Basarab (a.k.a. Dory) from Karen Chance's second series describes herself as small and curvy. Vampires often underestimate her because she appears cute and harmless. She is still, however, a 500 year old dhampir who can easily tussle with all but the most powerful of vampires and other supernatural creatures. During one of her "berserker rages", two First-level Masters could barely hold her down, and are implied to only have managed because one is her father who has incredible mental abilities and hundreds of years of experience in dealing with her. It was revealed in the third book of her series that her "berserker rages" are a result of her her extremely old and powerful vampiric blood taking over, as she is normally in human mode.
In Those That Wake's sequel, What We Become, once he gains access to the neuropleth the wizened Old Man becomes obscenely strong.
Live Action TV
River Tam from Firefly. Physically, she's small and slight, but since she's a genius, has psychic abilities, and was honed to be an assassin at the Alliance Academy, she can kick all kinds of ass without breaking a sweat.
Buffy is a human magically endowed with demon-like physical strength to balance out the super-strength of demonic opponents. While Buffy herself is tiny, some of her predecessors are physically larger with basically the same power level. Some Wizards did it.
Vampires in this series are like that as well.
Considering that the super strength of both Slayers and demons is mystically endowed size doesn't matter at all. The strength is clearly not in the muscles.
This is zig-zagged. Buffy does a lot of physical training, and clearly not just to refine her technique. Also, unactivated Slayers and vampire hunters can go hand-to-hand with super strong demons, apparently just because of practice. Never mind that most demons are perfectly capable of one-handed neck snaps.
Faith is slightly more physically imposing than Buffy, and her fighting style favors powerful strikes. She still shouldn't be able to hit like a truck without Slayer powers.
Also true of Connor. He is very thin and has no noticeable muscles but has enhanced speed and agility, lightning fast reflexes, and can punch a demon across a parking lot without even trying.
J. August Richards said in an Angel commentary that he didn't like having to describe his role in the group as "the muscle" when later in the same episode he's seen shirtless and has no discernible muscles. And his character was a non-powered human, so he doesn't even have the excuse that A Wizard Did It.
Subverted with Illyria; she can hold her own against weaker baddies, but on a level playing field, a bruiser like Hamilton spells trouble.
Discussed in Corner Gas when Brent explains to Lacey that arm size doesn't directly translate to arm wrestling victory... well, unless they're Lacey-small.
Niki/Jessica Sanders, Knox, and now Mohinder on Heroes.
There was also the soldier who was injected with the Super Serum.
Elliot from Scrubs has "fingers like biceps", and can force a nearly-closed elevator door back open with her pinky finger. Not bad for a gal from an orchard in Connecticut.
J.D. (thinking): "Oh no! Elliot has the pinky-strength of a rock-climbing jazz pianist!"
She is also shown to have absurdly strong thighs, to the point that she can break lunch trays with them.
Babylon 5's Minbari, memorably when Lennier picks someone up by the throat and holds them with his arm held straight and level and not bracing himself. All whilst calmly explaining that although looking much like a human he really is an alien.
The Doctor is occasionally shown to have this ability. The Fourth Doctor once karate-chopped a brick in half, and the Eighth dented a heavy steel door in the process of knocking it off its hinges.
Star Trek: Vulcans (and their kin, the Romulans and the Remans) are twice as strong as humans - Spock has effortlessly wiped the floor with Kirk at least two times in the series. And Data is an android with the strength of 10 men.
Data's strength is shown initially in "Encounter at Farpoint" when he lifts Riker up. Later, when a Klingon tries to challenge him in their version of arm-wrestling (B'aht Qul), Data wins effortlessly, at which point the angry Klingon tries to headbutt him and is staggered by the impact. Data points out that his skull is made of the same stuff they use to make starship hulls.
Vulcans are even stronger in Sondra Marshak and Myrna Culbreath's fanworks. In The Promethean Design, where we meet the legendary Vulcan admiral Savaj, Vulcans are revealed to be virtual demigods. He preaches at Spock to admit he's living in a World Of Cardboard and not indulging his full Vulcan potential. This is their explanation for why there are all-Vulcan ships like the Intrepid. At one point, having taken this to heart, Spock actually leaps a tall wall in a single bound.
In Friends, Monica is noted to be "freakishly strong", despite her size.
X-5 series transgenic supersoldiers in Dark Angel. While Zack is fairly bulky, Max and Alec have roughly the same level of enhanced physical prowess.
In Chuck, a new version of the Intersect computer can upload martial arts skills into a user's brain, giving guys with Geek Physiques the ability to beat up trained soldiers without any change in muscle size.
In iCarly, Sam Puckett is apparently strong enough to manhandle anyone she needs to, despite Jennette McCurdy, who plays her, being absolutely tiny. Freddie Benson, after his actor, Nathan Kress, gained a ton of muscle, lost an arm wrestling match with her, despite it being clear his arm is nearly twice as thick as hers.
Pro wrestling usually averts this trope, but when WWE had The Hurricane, he would often chokeslam wrestlers several times his own size. (The chokeslam normally being reserved for huge wrestlers.) Hey, he is supposed to be a Super Hero, after all.
only when he was a good guy. When he first entered the WWE and was a villain, it was played for laughs.
There was also He Who Must Not Be Named (Chris Benoit). Part of his "Silent But Violent" persona was that he was ridiculously strong for his size and able to perform power moves on wrestlers literally twice his size.
In one of his books Mick Foley once wrote that when a wrestler had a less than stellar physique, the commentators would often cover for the wrestler's ability to throw guys around by claiming they had exceptional tendon strength. In some cases, such as with Dan "The Beast" Severn, it was true.
While it is normal for lightweight wrestlers to be squashed by the big guys they are plenty of cases where the smaller guys (and girls) can get the win against them. This can normally only be done with high flyers who rely on hit-and-run type tactics.
ECW's Little Spike Dudley made a career of this as a "Giant-Killer," who would run into the ring, low-blow his opponent and hit the Acid Drop (running-up-turnbuckles bulldog) and pin the big guy in about 15 seconds or so.
If you're a muscular WWE Diva then it's not wise to assume the Waif-Fu girls will be an easy win. Just ask Beth Phoenix.
Another classic example: Tazz. All of 5'9 in a sport dominated by guys who average 6'5 at least, and without a really heavily significant definition in arms or legs. He did, however, have a build normally associated with lumberjacks. He was known as the "Human Suplex Machine" and was able to fling guys a foot taller and 100+ pounds heavier than him. Like his namesake, he was also prone to yelling at you before dropping you on your head.
David Otunga and Wade Barrett actually addressed this in the finale of the first season of NXT. Otunga (who is a bodybuilder) was teasing Barrett (who is a bare-knuckle fighter) about looking a little weak compared to him. Barrett promptly shot back, saying what amounted to, "You train to look pretty, I train to fight."
Vampires' bodies are preserved at the moment of their Embrace, but they can still increase their physical capabilities and boost them further through Disciplines, so that 90-pound wisp of a girl might be as strong as she looks - or she might be an elder that can tear someone's head off before they ever see her running at them.
Mages can augment their bodies magically, giving themselves superhuman strength and speed without any visible sign.
Prometheans are made of dead flesh animated by the Divine Fire, so muscle counts for something, but their Refinements let them smash conventional human limits out of the ballpark with a wielded telephone pole if they train up.
Demons, spirits, and Abyssal entities can manifest physically, but their bodies are more symbolic than indicative of their power. Nobody should ever believe that the gawky, emaciated Prince in Tattersnote (From the Summoners sourcebook.) can't thoroughly ruin their day if they get within reach of its scrawny arms.
In Exalted, the physical prowess of an Exalt is more linked to the way Essence empowers his body than to the amount of muscles. This is especially true for supernatural Strength level; someone with Strength 6 or 7 will usually look very strong, but not more than any well-built guy although he can casually bend thick steel bars, punch metal-reinforced doors out of their frames or lift horses.
Also, the Celestial Exaltation is usually bestowed upon physically hale individuals in the prime of life, but it is not unheard of that it chooses unusually young (13-15 years old) or old (up to around 65) hosts. So this little girl or that old man can actually be a chosen of the Sun able to fight 20 elite soldiers and win without a sweat.
In In Nomine Satanis / Magna Veritas, players play angels and demons who borrow the body of humans, and the body they get is basically the one that are available when they get incarnated, so there is no relationship between the abilities of the angel/demon and the appearance of the body. This skinny blonde can be a warlike angel and master swordsman able to cut through legions of demons, and that cute little boy can be a powerful demon that will casually break your neck the first time you look away.
Warhammer has this to some extent, when one compares the physiques of the miniatures for warriors with the same Strength (S) characteristic. A standard Orc warrior, for instance, has a Strength value of 3, which is the norm, despite that Orc model having gigantic muscular arms bigger than a man's torso. An elite High Elf White Lion Axeman, however, has a Strength of 4, despite the model's slender and willowy frame. Admittedly the biggest disparities tend to come with non-human characters, and could be chalked up to their peculiar biology or magical nature, but it is still noticeable with human models too. Normally proportioned Empire State Troops, for instance, have the same S3 as Chaos Marauders, who are all built like Arnie in the wrong aspect ratio.
Kroot may not look as strong as Space Marines and Orks due to their slim bodies, but they will fool you. Their muscles work by rapidly contracting, snapping and whipping like elastic. They may not have a lot of lifting strength compared to the previously mentioned examples, but if they whack you, you will feel it, and they're fast too, so they can keep up with other races. According to Word of God, their design was inspired by Maasai warriors, who tend to be tall and lithe.
In the same vein, the Eldar. Eldar look downright puny compared to humans, but, naturally, their musculature systems are very efficient and that makes them just as strong as we are. As a demonstration, this◊ is a Catachan Jungle Fighter, and this◊ is an Eldar Farseer. They're both Strength 3.
Abberrant has Mega-Strength as one standard power, but since all Nova abilities are subconscious quantum effects, it has literally nothing to do with actual muscular strength, so you don't have to have big muscles if you don't want to. A lot of Mega-Strong Novas do have big muscles, but it's more because they think they should have them, not because they need to.
In Super Smash Bros. Melee, the Fragile Speedster Fox is not only possibly the fastest character, he also has two of the most powerful KO-moves in his up-aerial and up-smash, the latter of which is the second-most powerful of its sort in the whole game, easily beating the much slower up-smashes of Donkey Kong and Ganondorf in terms of raw power. And the strongest up-smash? Pikachu's.
Who has the strongest of all moves in the game? Is it Captain Falcon? Nah. Os it Donkey Kong? Nope. Is it Mewtwo? You're getting warmer. Surprisingly, it's Jigglypuff, which already unsettling seeing that she's a small Pokemon with absolutely no muscles, is even weirder because she is the second smallest Pokemon in the game. Although her Smash move is hard to connect and, if done wrong, can leave her sleeping and an incredibly easy target, if done correctly, she can send and opponent with at least only 50% damage flying off stage.
This can be seen in MMORPGs as well. Since character appearances are purely aesthetic, a large muscular character could be defeated with ease by a smaller character.
Or a gnome, who in many cases will be swinging weapons larger than him/her self, and is just as capable as a tauren of tearing you to shreds.
Not just MMO's, any game with a customizable strength stat is susceptible to this because often the character model doesn't match the stats. Case in point, in Final Fantasy X, a properly-trained Yuna can do more physical damage than any other character, including Tidus and Auron. With a blunt stick, no less!
Try attacking a Behemoth with a levelled up Yuna doing 99999 damage. The wimpy sound she makes as she swings her staff just makes it that much stranger.
Mario as well; he can do things like lift Bowser by the tail, spin him around swiftly and throw him across an arena with just his arms in Super Mario 64, despite being a short, somewhat pudgy guy.
In the third Gears of War installment features Female COG's to the mix, who have normal/slender builds. This is a very blatant contrast to the average Male COG and Locust drone, who are huge and muscular, easily outweighing the Female COGS by more than 100%. This has no effect on their effectiveness in combat, with female cogs just as easily dragging around heavy weapons, and going toe to toe in HTH combat. Very blatant in this◊ screen shot where a female COG bayonets a Locust and actually lifts off the ground. Note that the locusts arms are about as big as her torso.
In a word, Disgaea. Someone who looks like this◊ should not even be capable of lifting the sword he is holding, much less be able to deal absurdly high amounts of damage or lift and throw ten significantly larger people at once.
Or blow up planets...
Kingdom Hearts' Sora, like most Kid Heroes, is short and has skinny stick limbs, their twiggyness only emphasized by his clothes and big shoes—yet he regularly beats the tar out of adult men and Mooks several times his size. For a villainous example, NPC Axel, especially the Bonus Boss version, should not be able to deal the damage he does with a frame like his.
Same thing that applies to Axel, goes with Larxene.
This is lampshaded early on in the first game, with Jafar openly stating that "the boy's strength is not his own". It's implied that a combination of the Keyblade's magic and The Power of Friendship is what allows him to kick so much ass.
Lampshaded again in 3D when Xigbar tries to use it as a way to break Sora's resolve, He dosen't seem to care.
Link from The Legend of Zelda is generally on the small side and, even as an adult, doesn't get much bulkier than "wiry bishonen" (and, if you're willing to go outside canon and take SoulCalibur II as a visual reference, barely grazes even five feet). He also generally lacks any super powers beyond an absurd level of courage and maybe a few acquired spells. So how is it that the guy can fight toe-to-toe with the hulkingBig Bad or spontaneously perform backflips while wearing chainmail? And that doesn't even get into the time he out-Sumo Wrestled a giant rock creature because he was wearing heavy boots.
Little Mac from Punch-Out!! isn't even five feet tall and weighs a little over a hundred pounds, but he can defeat a variety of legendary heavyweight boxers such as Mike Tyson himself. This isn't due to his physical prowess but rather due to exploiting their stupidity and fighting patterns.
Mega Man allows you to gain the same strength as Gutsman, a boss robot at least twice your size. The strength Mega Man shows in the end of the fifth game needs to be seen.
Saber from Fate/stay night is a little over five feet tall and is built like a somewhat toned fourteen year old, and yet is capable of parrying blows from a ten foot tall crazed Berserker. This is because of her Mana Burst ability, where she consumes magic to perform superhuman feats of strength and endurance. When she's suffering from mana deprivation, she's about as weak as she looks. It is explicitly stated that without magical energy she is weaker that Shirou and Rin in terms of physical strength.
Legacy of Kain: Physically, Raziel is barely more than a walking skeleton, but, as the Elder God states, he's actually stronger as a wraith than he was as a vampire. He can easily push and pull massive stone pillars and overpower vampires.
Kinda averted in Tsukihime and the Nasuverse. Arc and Saber are stated to be as weak as they appear if not for their high levels of supernatural magical energies. Then again, it does fit this trope in that Muscles Are Meaningless compare to magical energies and just about everyone that matters uses magical energies.
Played with in Prototype. Standard human-sized Alex can lift cars and kick helicopters apart with about 3 hits and the Supreme Hunter is a fair powerhouse despite not being much bigger. This is justified as both actually weigh far more than they appear on the surface. On the other hand, the standard human-sized Infected don't pose much threat in melee, Alex's Muscle Mass power (Exactly What It Says on the Tin) noticeably increases his melee power, and the various Elite Mooks that do pose a problem in melee are hulking bruisers towering over Alex.
Makoto Nanaya of BlazBlue, despite being a squirrel girl who only weighs 49 kilograms (108 pounds), is one of the most powerful characters in the game, able to do a lot of physical damage with just her fists. This is not Gameplay and Story Segregation either. In one cutscene she drops from the air and leaves a large crater where she punched the ground and, to further let you know how powerful she is, she effortlessly picks up and carries off an unconscious Tsubaki like she were a rag doll.
Female Shepard Mass Effect, unlike her reasonably built male counterpart, is something of a waif when out of armour. Nonetheless, this doesn't stop her punching krogan to death if she gets close enough. Due to the Lazarus Project in the second game, Shepard has been outfitted in cybernetic implants and a reinforced skeletal structure, allowing her to fire sniper rifles and shotguns designed by Geth and Krogan, which generate enough recoil to shatter every bone in a normal human's arm.
In the second game, an over-amorous Turian makes the mistake of hitting on an Asari and a Female Shepard, before insulting them. Cue the sound of him being beaten to a pulp offscreen, then thrown clean across the room. Made even more amusing if Shepard's wearing the cocktail dress from Kasumi's DLC at the time.
Even more obvious in Citadel where you get the chance to beat Vega at pull-ups, with a whooping score of 182
One of the augmentations the Spartans received in the Halo universe was a thyroid implant that increases their muscular density significantly (tying in to the real life science mention in the description). Spartan II's were "7 foot tall walking tanks" but they became known that way before their strength enhancing Powered Armor made them into near unstoppable soldiers. In a story surrounding the augmentation of John-117, at age 14 he already had an adult Olympic-level physique and after recovering from the thyroid implant he was physically far superior to a pair of ODST special forces soldiers, who made the mistake of trying to push him around...
While not as scrawny as some of the other video game characters listed, in Team Fortress 2, the Scout is able to sending enemies flying with a baseball bat, including the Heavy.
Cloud from Final Fantasy VII. He's 5'7", making him the shortest human male in the cast. Also, while having very well defined muscles, is much smaller than Barret. Yet he's significantly stronger than anyone else in the party and in Advent Children he carries Barret one-handed at high speed.
Fenris of Dragon Age II is an elf, which in this game means very thin and lanky, but specializes in two-handed weapons which not only include greatswords but hammers and axes as well. Helps that he has Lyrium laced throughout his body.
A Female Hawke specialising in wielding two-handed weapons also falls into this trope, being less muscular than her male counterpart. Her proficiency with these weapons is somewhat justifiable however, due to both her and her brother Carver being trained in swordsmanship from a young age by their father, as well as being one of the few survivors of King Cailan's Army at Ostagar.
In Saints Row: The Third, at your complete whim you can change your hulking, muscular beast of a character to a stick-like bishie twerp on the spot via plastic surgery, but you can still drop kick grown men, throw people across a highway, and manhandle a brute with a baseball bat like it's no big deal.
Most fist fighters and two-handed weapon users in Tales Series tend to fall into this category.
Colette and Presea from Tales of Symphonia are, among other things, both shown to be capable of carrying things larger and heavier then themselves with ease despite being devoid of any noticeable muscle. This extends into gameplay in the latter's case, who wields enormous axes with ground shattering force.
Senel from Tales of Legendia looks to be of slightly above average musculature at best, but is nonetheless capable of throwing around monsters about three times bigger than himself with ease.
Karol from Tales of Vesperia wields hammers with heads almost as big as himself along with swords and axes that are twice his height and is a simple 12 year old boy. He does have a possible justification in the form of the blastia on his handbag, though.
Averted with regards to normal enemies, though, as Sammy is the only character who can't throw an opponent using his strength alone. while even the short but muscular Blaze can throw out out a suplex or three, Skate's only actual throw comes from flipping over the opponent and using the momentum and leverage to toss them forward.
Knuckles in Sonic the Hedgehog, as well as Mighty in the comics, are both roughly the same size as Sonic (Knuckles is a little shorter) but have the power to match the likes of Vector, Storm, Big, Omega, Wario, Bowser, and even Donkey Kong In Mighty's case, he was given super strength by Mammoth Mogul and while the comics explain Knuckles was experimented on at birth the games offer no such explanation for his power.
This is averted in Knuckles' case in the upcoming Sonic Boom where his character design is noticeably more muscular.
The Inexplicable Adventures of Bob!. Molly's alien pet Snookums is about the size of a basketball, but began as a giant monster before getting shrunk. He retains all his original mass, so the ground shakes when he hops around, and he can defeat much larger opponents simply by hopping into them.
In evidence in Tales of MU, where many characters' strength comes from magic. The protagonist Mackenzie Blaise is among the stronger characters, but appears to be an underdeveloped eighteen-year-old girl. Puddy is more muscular in appearance, but not enough to account for the fact that she's sometimes stronger than a dragon.
In the web fiction Whateley Universe, you certainly can't judge strength by muscle bulk, because everyone at the Superhero School Whateley Academy is a mutant including plenty of the teachers. Sensei Ito is a tiny little old man.. who starts every term by demonstrating that he - an ordinary human with no mutant abilities - can beat the crap out of the most dangerous mutant in the room. Phase is five-foot-nothing and too skinny (he just grew three inches), but at full strength he can dead-lift nearly two tons.
Usually, Kim: perfectly willing and able to knock down men twice her size. Even discussed when she and Shego faced two huge wrestlers while Trapped In Tv Land; "Well, this shouldn't be a problem."
Ron and Drakken's henchmen wear muscle-enhancing rings in "Ron The Man", but it's still Kim and Shego doing most of the fighting, maybe even more than usual.
Seńor Senior Junior is the most buff-looking of the regular villains, but doesn't get into fights. Maybe he doesn't want to mess up his hair.
The Powerpuff Girls. They can defeat a muscular and super intelligent talking monkey, several large criminals, the finest in technology and human advances that money could buy, an extremely muscular (and kinda fat) pink hillbilly monster who's only truly terrifying when he actually does flex his muscles, several giant robots, monsters, genetic mutations, and even satan himself. Keep in mind that we're talking about three kindergarten girls.
Disney's Hercules, especially in the beginning of the toon. Initially he is quite small and thin but superstrong no matter what.
The Boulder is a very large man who's muscles are so impressive that even he can't help but perform a muscle show and a pec dance for his audience. Aang even questions learning earthbending from this manly earthbender. He defeats every man and woman he battled at an underground earth tournament, all with barely a scratch. Then, who does he face last? Toph, a little blind girl. Guess who wins and becomes a main character.
In Toph's case, this relates specifically to her earthbending. She is clearly very strong for her size and age, often hurting her teammates, no pushovers themselves, with with playful punches. However, situations where she lacks earthbending tend to emphasize her helplessness. This is partly because it takes away the Disability Superpower that allows her to bypass her blindness, but she never demonstrates superior martial arts skills when not aided by her earthbending.
Aang himself, being only ten, does not have the cut, muscular physique that most other male characters like Zuko have, since as a pre-pubescent, it is physically impossible for him to build significant muscle mass. However, he is the most powerful bender in the world and relies on superior speed and agility to take down much bigger opponents. In season 3, however, he switches to a costume that leaves his arms and part of his chest exposed, showing that he has an incredibly defined, but lithe musculature. The final battle between Aang and Ozai ends with a grown man in at least his thirties built like a brick wall being tossed around by a skinny child.
Dave the Barbarian is a very tall muscular guy but he's a total wuss who can't fight worth a damn and always gets his ass kicked by people and animals smaller than him.
Zig-zagged by Cody of Total Drama. He's able to knock out Duncan in one episode but can't even lift a cardboard box in another.
In SilverHawks, Genius Bruisertwins Steelheart and Steelwill exemplify this perfectly. Steelwill is huge and brawny, to the point his facemask looks like a football helmet. Steelheart looks like a very athletic woman, but even she looks positively tiny next to her brother. And yet, they're equally strong and evenly matched in any physical contest, making Steelwill's towering bulk look... inefficient next to his sleeker, more compact sibling.
She's also a Jedi, and considering Anakin's Papa Wolf tendencies, it wouldn't be out of character for him to teach her how to amplify her strength with the Force. It can be done, and this might be what happened, as up to about season two to mid season three (pre-timeskip) she possessed strength normal for a girl her age, i.e. unable to lift Anakin, a 6'1" adult man (which she later did in Season Five).
All the ponies in My Little Pony: Friendship Is Magic seem to possess strength far beyond their size and figure, from earth ponies pulling a five-compartment train at full speed, to pegasi floating a moving car full of anvils, carts, and pianos.
In "A Dog and Pony Show", Rarity (one of the relatively weak unicorns) could pull a cart full of diamonds with ease while three Diamond Dogs could barely move it.
In "Dragonshy", a montage of the ponies getting ready to confront a dragon features Applejack's much larger brother Big McIntosh lifting a heavy set of saddle-bags onto her back with great effort. She sags under the sudden weight, but easily straightens up and leaps into the air. This may be meant to imply she's stronger than he is ("strong" is certainly a description associated with her) — but not necessarily, since he does have to lift it with his neck muscles rather than whole body.
In "Hearts and Hooves Day", Big McIntosh is shown to be strong enough to tow an entire building, presumably having shorn it clear off its foundation. Likewise, in "Lesson Zero", he was shown to be strong enough to toss an entire mob of ponies—most of the town, in fact—off of him with just a shake of his frame. It's clear that, strong as Applejack is, her brother is stronger still.
Partly Truth in Television. Ponies are known for possessing the ability to carry quite heavy loads, even those that match their body weight.
Partially averted at the same time. Big McIntosh is actually extremely strong, as shown in Lesson Zero when he launches pretty much everypony in Ponyville off of himself to get at the Smartypants doll.
Team Umizoomi has Geo, who can easily lift one person and several cartons of milk even for his size and age.
Starfire from Teen Titans isn't noticeably muscular in build, yet she can bench more than Cyborg without difficulty. Her secret? "Boundless confidence!"
Olympic weightlifters usually have less muscle definition than bodybuilders while generally possessing superior strength.
Typically, bodybuilders train for more visible muscles to win competitions based on showmanship. Powerlifters and Olympic weightlifters train for 'neuromuscular response' and hypertrophy, to attain maximal strength and explosive quickness, and generally have little concern for the appearance of their physique. There's a slogan amongst fitness communities, "Lift for strength, eat for size." The big difference between bodybuilders and powerlifters tends to mostly be diet. Bodybuilders will often diet down to increase their muscle definition, while powerlifters, who don't really give a rip, just let that physique-softening layer of fat stay.
The strongest Olympic weightlifters are, in general, very large men (weighing in excess of 150kg, bigger than most bodybuilders.)
Bruce Lee was about 160 pounds at his heaviest, and slimmed down in later years. By his movie-making prime, he was about 135-140 pounds, 5'7, and could do pushups with a 250 pound man standing on his back. Of course, Bruce was no average 160 pound man; his physique was extremely muscular.
The biceps and pectorals are the muscles that many people (erroneously) believe to make up the bulk of physical strength. In actuality, muscles like the Latissimus dorsi and triceps contribute far more to functional strength (especially the Latissimus dorsi). Bruce Lee is an excellent example of this: his biceps and chest were not abnormally large for a man his size, but his Latissimus dorsi were enormous.
A 6-pack abs does not indicate strength; muscle definition means that there simply isn't fat covering up the muscle.
When someone is armed with the right knowledge (where to strike) and the training to match, a heavily muscled opponent can go down as easily as anyone else.
In boxing, the guys who tend to be longer and lankier almost invariably wind up being the hardest punchers around. Alexis Arguello was famously known as the Explosive Thin Man and like his nickname implied, had true one-punch knockout power in either hand. This tends to be because leverage is much more important for generating knockout power as opposed to brute strength, and the most muscular fighters tend to be at a disadvantage because they typically lack the conditioning to go deep in fights.
Averted by people like Earnie Shavers and George Foreman. It's extremely hard to tell what exactly makes a good puncher tick.
Studies suggest that the synchronization of the wrist and shoulder movements is the key to a powerful punch, rather than sheer muscle strength.
Humans are designed to have extremely high endurance rather than high peak strength; as a result, many animals, pound for pound, appear considerably stronger than humans do - chimpanzees, for instance, are roughly twice as strong as humans are for a given body weight. This is also why many animals seem very fast compared to humans. Even on a human-to-human basis, some people are better at things which require a lot of power over a short period of time and some are better at things which require less power over a longer period of time as a result of their genetics.
The surge of adrenaline that occurs when someone is terrified can override the usual safety limits that stop us from contracting more than about 1/3 of a muscle's myofibrils at a time. This increases strength enormously, but at a cost: neither muscles nor tendons can tolerate such extreme tension without risk of injury, meaning that someone who uses all of that extra strength is likely to suffer tendon and muscle tears, or even broken bones.
Soldiers are seldom very big; often they have a bit of a gut to them.
Most special forces and infantrymen tend to have either a skinny but toned build or a (very) slightly chunky build. You're not going to see a group of guys like Arnold, Weathers, and Ventura in Predator. (Note: Ventura is a rare exception, he was a Navy UDT.) If you look at a group of SEAL trainees for example, they're more likely to have a little gut than a six-pack. For them, it isn't about looking good, but its about being good (having to combine raw strength, power, endurance and agility all at once). According to Dick Couch, almost all the bodybuilders that show up to BUD/S drop within days because they cannot keep up because of their mass.
In one episode of the Military Channel's series Surviving the Cut, the trainees in question were wannabe Army combat divers. Unlike episodes featuring other elite units where there was a large variety of body types, the trainees in this case all looked relatively massive: they had to be very good swimmers before they arrived at the course, and anyone putting in that much time in the pool to get ready for the course is going to have big shoulders and arms. It's very possible to not get selected for being TOO big if you survive selection.
One discovery made during World War II regarding cold weather combat was that soldiers with less than 5% body fat tended to have the most trouble with shivering. The reason is that when the body is put under stress fat cells are the quickest and easiest source of energy the body can tap into to counter the stress, this is why exercise burns fat and why you lose weight when sick. It's now recommended to never get below 5% body fat for that very reason, as it leads to other health problems.
This is why "fit or fat" is a misnomer. "Fitness" means appropriate to the environment, not thinness or athleticism. Inuit and other Alaskan Natives eating their traditional food are fit to their surroundings.
While machines were adopted for weight training because they keep the weight from moving around in an unsafe manner, this has turned out to cause more injuries than traditional methods because it works out major muscle groups without also engaging stability muscles. In recent years, there's been a shift to "strongman"-style training with awkward loads (sandbags, water tubes, medicine balls, etc.) to give athletes control to back their strength.
Varya Akulova. Amazingly strong and has been lifting weights since a very young age. At her early teenage years she could lift 350 kg (770 pounds) and herself only weighed 40 kg (88 pounds).
Alain Robert, aka "French Spiderman", is, like many professional rock climbers, fairly short and lean, but also very strong and has a high level of endurance. In his autobiography he recounts stories about how, during some of his short stays in jail, he won the respect of bigger and bulkier inmates by perorming feats of strength such as doing forty one-handed push ups in a row.
This is an interesting thing about performing a suplex. Most women's centers of gravity are low, whereas most men's are higher. Men also tend to be taller than women on the whole. This means that it's actually extremely easy for a lot of women to suplex the majority of men, even if they aren't physically strong— grab them under the butt around the thighs, and then just lean back (or, if they grab you from behind, cling onto their arms and roll forward like you might have done as a child, aiming to land on your shoulder). It's a pure case of physics over strength. You can see a beautiful example of this here.
Roger Moore was mocked by critics for not looking tough enough to be an action star. Moore beat up one of his critics, Lee Marvin, and proved that while he doesn't look like it, he's built like granite.