In Haou Airen, Hakuron went up the Triads's ranks via basically kicking all kind of ass to get there. Also, that's how he recruited Di Long into the group.
In Naruto, the hidden villages of the Five Great Shinobi Countries are each led by a Kage; candidates are required to be one of the strongest ninjas in the village. However, deficiencies in intelligence and/or character can sometimes disqualify a candidate. In general, this principle of allowing only the best fighters to take the top leadership position seems to apply to any nation/organization run by ninjas and/or samurai.
While Hokage candidates also need to be approved by the Hidden Leaf's elite ninjas in order to take office, it's still implied that they won't even look your way unless you've proven yourself as one of the village's best.
This principle of requiring both combat and leadership abilities applies to promotions in general; the Chunin Exams themselves function more as Secret Tests Of Character, since merely winning all of your fights will not guarantee a rank up.
Goku is the de facto leader of the Z Fighters in Dragon Ball Z, not because he is the smartest (in fact he is one of the least intelligent; the title is probably taken by Piccolo), or because he is a great tactician (Vegeta probably takes that one); no, it's simply because he is the strongest of the group by a huge margin.
Not necessarily: Goku should be classified as more of a Genius Ditz than "the least intelligent"—it's just that his intelligence seems to more attuned to combat than anything else. For example, he incorporates his knowledge of the speed of light when fighting with Frieza, and a lot of the tactics he comes up with are quite clever. If you watch the series, you know he doesn't just win by repetitious punching. Vegeta on the other hand, the alleged "tactician", seems to employ the berserker method more often, particularly during his fight with Cell.
Goku is seen as the de facto leader not only because of Asskicking Equals Authority, but also because he tends to keep a cool mind when things goes to hell. Even when he is not the strongest, he tends to set systems in place that help the characters in the long run, like restoring the Dragon Balls after Piccolo and Kami fused, training Gohan to surpass the limits of a Super Saiyan, and teaching Trunks and Goten the Fusion Dance.
Vegeta is a very good tactician, when he is cool-headed. When Vegeta is upset or being overly prideful, he tends to regress to tactics of throwing energy blasts until the target is dead.
Although this isn't always the case, Vegeta was stronger for the first half of the Android/Cell arc and Gohan surpassed him ever since having the Old Kai unlock his power.
While it is debatable if Gohan is still stronger than Goku at the end of the series, the reason why Gohan is never seen as the leader despite his power is because he tends to rely on his brute strength more than the other fighters. Gohan tends to do poorly against opponents who are equal or a little stronger than him since he cannot just overwhelm them, while Goku, Vegeta, and Piccolo can fight or even bring down opponents stronger than themselves by using fighting tactics.
Straighter example with the Saiyans. King Vegeta became king because he was the strongest of them.
As noted on the Pals with Jesus page, the main characters of Dragon Ball Z get to choose who the official God of Earth is almost entirely due to strength, and aren't afraid to strong-arm gods higher up the chain if need be.
InuYasha: Bankotsu tells Inuyasha that he's the leader of the Band of Seven because he can outfight the other six.
Since one of the main, and most important requirements for a person to become an General of the Black Order in D.Gray-Man is to have over 100% synchronization with their Innocence, this is naturally what happens.
The Soul Society that polices the afterlife in Bleach works like this. The Soul Reapers that act as the military for the Soul Society are divided into 13 divisions known as the Gotei 13. While captains for the divisions are usually trained and schooled for centuries, the single most important quality required to become a captain is raw strength - so much so that Kenpachi Zaraki was made the captain of the 11th division when he killed its previous captain, even though he never attended the soul reaper academy. Meanwhile, Head Captain Yamamoto Genryusai, the Captain of the 1st Division, is so powerful that he has never fought at full strength on-screen (or on-page) and still almost managed to accidentally blow up a city. It's even been stated most captains are more powerful than the entire rest of their division.
The Espada also work like this. Most Arrancar numbers correspond to when they were created, but the numbers 1 through 10 and 0 are given to the ten strongest, with the lowest numbers being the strongest. 11 through 99 are the less powerful subordinates of the first ten (though their numbers shown the order they became arrancar in, rather than power), and 100 and up are former single digit hollows who have been replaced.
Furthermore, at least three of the Espada are known, before joining the organization, to have led their own bands of hollows who followed them largely because they knew the leader could kill them on a whim and the current employer of the Espada pretty much came into power by demonstrating the casual ease with which he could slaughter pretty much anyone.
While the laws of Soul Society allow the Captain of any Division to be replaced by someone who kills them in single combat, the 11th Division in particular (which, unlike the other Divisions focuses exclusively on combat) has this as its long-standing tradition. Every Captain of the 11th has attained the position by killing his predecessor. Whether any other Division has ever used this method of successor hasn't been specified.
Yhwach states the reason Yamamoto is in charge of the Gotei 13 is because he set up the original "13 Divisions", a group of powerful, terrible thugs, of which Yamamoto was by far the worse. While Yhwach states Yamamoto has mellowed since then int "weakness", Yamamoto himself told Aizen that the reason he was still captain-commander is because no-one born in the last thousand years had been more powerful than him. Yamamoto is therefore an overlap between this and Authority Equals Asskicking.
Ultimately subverted with the Gotei 13, however. While this trope applies internally, they are still ruled by the Central 46, Soul Society's governing body mostly composed of nobles who don't actually fight. However, this doesn't come up much as they are killed off during the Rescue Rukia Arc, leaving Soul Society in a state of martial law until after the Time Skip.
Raoh's goal in conquering the world in Fist of the North Star is to bring about a society like this, albeit one that is much more united than the Crapsack World that exists after the nuclear war.
The Three Kings arc in YuYu Hakusho plays with this. At first, there are three warring countries, each led by the strongest fighter. Eventually, everyone agrees to hold a tournament, and crown the winner ruler of all demon world (until the next tournament). The strangest thing is, it works perfectly, even though none of the protagonists made it into the finals. Neither of the two surviving kings win either; instead, an old sparring partner of the recently deceased third king wins.
Tenchi Muyo!Word of God states that this is how becoming Emperor of Jurai works. Ordinary Earthling Seina Yamada from Tenchi Muyo GXP learns that stumbling across a Humongous Mecha with a seed for one of Jurai's space trees catapulted him near the top of the list of potential heirs. The title character, Tenchi Masaki, would be at the top of the list if he had any interest in the job; the creator's semi-official doujin works indicated that eventually he will.
While Dynastical Council in Crest of the Stars evaluates not only the martial prowess of the potential candidates to the Jade Throne, it's still one of their major consideration, and to ascend to the title of Crown Prince, successful aspirant should rise in the military ranks to the position of Commander in Chief — with the Council constantly judging his or her performance and vetting the promotions accordingly.
Specifically invoked in Saiunkoku Monogatari when Rou Ensei explains how he ended up as the Governor of an entire province even though he hadn't passed any of the examinations normally required to qualify for government office: the Sa clan was causing so much trouble in the province that the Imperial court needed to appoint a governor who'd be able to survive their repeated assassination attempts. Ensei was their guy. (That he had The Chessmaster Tei Yuushun supporting him as Lieutenant Governor helped to keep the actual administrative side of things running smoothly as well.)
Yugioh GX has North Academy, where new students have to duel through a forty-man gauntlet to find out their rank. Chazz fights his way to the top and is immediately crowned head of the freshman class.
Not only that, but they also have to do it with a deck they constructed from scratch using cards found outside the academy
The society of Jungle Planet in Transformers Cybertron is based on this. A variant exists on Velocitron, where the planet ruler is whoever is the fastest.
Apparently the set-up of Shibusen in Soul Eater. The more successful the members, the higher their rank of between one to three stars. However, the time the main cast spent as Almighty Janitors would suggest this is less about strict hierarchy than it is about whatever Shinigami feels like putting his students through for his own reasons/amusement.
Not really legal in Code Geass - though it is implied that Charles killed his own father to get the position (at which point it became retroactively legal, since the Emperor is an absolute monarch). Lelouch manages to become Emperor by killing his father, and forcing the rest of his siblings to comply through violence and coercion. By which I mean mind control. Head of the Knight Bismarck Waldstein disagrees with the concept... but finds himself coming down with a case of death, with his killer taking Bismarck's place.
In Record of Lodoss War most rulers are semi-retired adventurers of great fame. Kashue, Parn, Etoh, Shiris, and Spark were all adventurers for many years, before they became rulers of their own countries. Fahn, Beld, Ashram, and Ryona were also great warriors as well.
Basically the entire premise of the Queen's Blade series. In a nutshell: assorted women of various fetishes fight for the right to become queen for a year. Even has two spinoff series for more characters and more fun.
One Piece has Baroque Works, where one's spot in the organization is determined by how much ass you can kick. If lower-ranked members can eliminate higher-ranked ones, they can move up in the ranks. Most of the top ranks are Devil Fruit users.
The Marines also play this straight. Captain (now Vice Admiral) Smoker gets to keep his position and often promoted despite being a Cowboy Cop largely thanks to his fighting ability and powerful devil fruit. After the time skip, the Marines have also recruited two new members entirely from outside the organization and promoted them straight to Admirals, because of their power.
Claymore has this. The organization that Claymores work for only has forty-seven Claymores active at any one time. If a Claymore dies, all the Claymores below her are automatically promoted one rank - and if a new Claymore is powerful enough to take a higher rank than #47, all the Claymores weaker than her are automatically demoted.
Of course, while Asskicking Equals Authority applies to Claymores while they're on missions, the ones who are actually in charge of the organization seem to have no physical power at all.
Invoked by the (probable) Big Bad Naosada Washizu from Gamaran: He has about thirty sons and rules over a region famous for martial arts and full of powerful warriors. His plan? Each of his sons will hire a Ryuu (martial art school), and those Ryuu will fight in the great Unabara Tournament: the heir with the strongest Ryuu will become the new Daimyo, with the members as his vassals.
Subverted in Tengen Toppa Gurren Lagann: after the Time Skip most of the members of Team Dai-Gurren are put in charge of the newly formed government entirely because they're such huge heroes. But, being for the most part a bunch of rowdy jackasses, the majority of them don't have any talent for or interests in politics and they know it. Until there's ass to be kicked, they're content to just sit back and be figureheads for the ones who actually know what they're doing.
In 12 Beast's alternate dimension of Live-Earth, populated by monster girlsand monster boys, positions of authority are rewarded to those that defeat their predecessor and/or the competition on the way up there. It really brings a new meaning to "biting and clawing your way up the ranks."
Attack on Titan deconstructs this. The military system in place makes sense on paper: the best and brightest defend humanity's center (the Military Police Brigade) and the rest either maintain the walls or go on scouting missions (the Garrison and the Survey Corps, respectively). This means ultimately the best soldiers are likely never to be where they're needed most, making them useless to the overall war effort. Few of them ever actually participate in combat. Additionally, any exercises that they do would involve drilling with their guns (as they are responsible for maintaining law and order) so the 3DMG skills that got them to the top are stagnated and see little further use because they're at the top.
In Judge Dredd, in the aftermath of the Apocalypse War, group of robots set up an independent city in the ruins of Mega-City One, with a wrestler droid as king. The law is that anybody who wants to change the way things are run must beat the king in a wrestling match.
In Wakanda of Black Panther, they hold a tournament where anyone can challenge the current king for the right to take the throne.
Sondra Marshak and Myrna Culbreath's Star Trek TOS writings are all about this. Especially in The Prometheus Design wherein we learn that Spock has been living in a cardboard world all these years. Vulcan superiority is their obsessive Author Appeal.
Want to know how to handle impatient hostages you're trying to rescue? Kick the crap of a Mecha-Mook, which is what Rob Jackson did in Power Rangers GPX.
Played straight in the Final Fantasy VII fanfiction Shinra High SOLDIER. Raw, one-on-one physical combat skill is the sole quality required to become the general of the entire Shinra army, by beating the previous one in the Challenges. Sephiroth, an 18 year old who had been a soldier for only a few months, defeats Heidegger and becomes general of the entire army. His 16 year old girlfriend Julia becomes commander by defeating Commander Kinneas.
In the Paris Burning universe, personifications of cities compete fiercely for the right to be capital of their country. Depending on the traditions of the society and the temperaments of the combatants, these conflicts can be long campaigns of political intrigue and underhanded violence, or simple face-to-face duels.
Saito Hiraga invokes this beautifully in Jus Primae Noctis when he storms into the tent with the rebel generals where they’re meeting under truce to negotiate and tells them to sit down, shut up, and surrender to Henrietta or he’ll kill them all. They're not technically bound to obey his orders, since they were trying to use this trope and stage a coup, but they submit.
Almost every single action movie hero takes charge of whatever situation they deal with, precisely because they're kicking the most ass and usually there is nobody who wants to challenge them.
The barbarian horde in The 13th Warrior retreats when their leader is killed by the leader of the heroes' side.
In The Quick and the Dead, Herod is the mayor of a small town because he has the most hired muscle on his side and he is nigh unbeatable in a gunfight.
In Avatar, Jake Sully proves himself the leader of the Na'vi by taking, as his personal mount, the biggest, baddest beast in the sky.
In Rise of the Planet of the Apes, Caesar's rise to power is attained by his asskicking almost everyone into submission, including his fellow chimps who become his army, his bullying handlers at the detention center, then the director of the research facility.
In The Avengers, Captain America has to rally the New York City police to respond to the invading aliens and evacuate the civilians. The police commander on the scene scoffs at Cap's orders, saying that he has no reason to listen to Rogers. Then three aliens suddenly leap down upon them, who Cap beats down in seconds with just his fists and shield. The police commander immediately spins around and begins relaying Cap's orders almost verbatim.
Godzilla. He didn't earn the title "King of the Monsters" for nothing.
Played for laughs in Idiocracy, where President Dwayne Elizondo Mountain Dew Herbert Camacho is porn superstar and five-time Ultimate Smackdown wrestling champion.
Though he was presumably elected, and was popular because of the wrestling and porn. Seeing how physically unimposing but smarter than everyone else in that era Joe Bowers becomes president after him.
At the end of How to Train Your Dragon 2, Toothless becomes the Alpha after challenging and defeating Drago's enormous Bewilderbeast with the help of the rest of the dragons. The rest of the dragons and the Vikings bow down to him.
Visser Three, from the Animorphs series, in The Andalite Chronicles, is a Hork-Bajir Controller with the respectable rank of Sub-Visser Seven. He's promoted to a low Visser rank immediately upon (and explicitly because of) his infestation of Elfangor's commanding officer and becomes the only Andalite-Controller in history. His rise turns meteoric from there. It helps that Visser Three had full access to all of the military knowledge in his host's (a high-ranking though disgraced Andalite warrior-prince) mind. Obtaining a prize like that would definitely warrant a promotion.
The Hyerne nation in 'Philosopher in Arms' chooses its queen through one-on-one combat.
The rank of queen in 'Branded' by Clare London is determined by a war game-style generalship competition.
Rehvenge in the Black Dagger Brotherhood series by J R Ward becomes the supreme ruler of the sympaths by essentially killing the ones in authority.
Gaining rank in the Star Wars universe has a lot to do with asskicking. Both Luke Skywalker and Han Solo are given senior officer status in the Rebel Alliance just based on the fact that they are awesome. Somewhat justified in that a rebel insurgency doesn't have the luxury of OCS and a career advancement system, but still odd that any random smuggler can become an instant General.
The Star Wars Expanded Universe makes it pretty clear that the Sith have generally operated on this principle whenever they have had a structure involving enough of them to do so- the Rule of Two just compresses it, so that one proves one's strength and becomes the Master by killing one's own Master.
In The Dresden Files the main character and narrator reflects that you don't get to become The Merlin, chief wizard on the planet, by collecting bottle caps. Since he is referring to someone who held off an entire Badass Army of Eldritch Abominations with one hasty ward, he may have a point.
In the Kate Daniels series, the Beast Lord is said to rule over the 300+ Shapeshifters of Atlanta specifically for this.
On a less malevolent scale, the Mandalorians also have a tradition of following their leaders based upon this trope. Whenever Mandalore dies (given the nature of their culture, this usually happens in battle), the strongest remaining warrior becomes the new Mandalore. This has been happening for over twenty thousand years.
More specifically, the strongest warriors fight over Mandalore's helmet. If there's no helmet, there's no fighting, and no new Mandalore. KOTOR 2 pointed out how ridiculous this is—Revan managed to deal the death blow to the Mandalorian people basically by just killing Mandalore and taking the helmet with him when he left.
They fixed that. Now either the current Mandalore chooses a successor (the person he or she feels is best fit to lead), or it's the guy who can get the most people the follow him. The second one happens if the Mandalore fails to name a successor before he dies.
The Lensman series by E. E. “Doc” Smith had multiple cultures which followed this method (though this is usually explained by the fact that all of the subject cultures consciously patterned themselves after the primary culture). The Eddorians, the Ploor, the Eich, possibly the Delgonians, and the entire Council of Boskone, fit this trope perfectly. Kim Kinnison even uses this to take over the entire bad guy's empire and become the Overlord of Thrale by assassinating the previous Overlord of Thrale, which was the accepted way of moving up in the world. It was stated that all of these cultures were fairly stable, in that underlings would not try for promotion until they were fairly certain that they could succeed, and in the meantime they had to produce for their superiors or they would be replaced, either by their superiors for not producing or by their own underlings for failure to protect themselves.
One of the two possible ways to get promoted to praetor.
Still in full effect for General Tyson of the Cyclops Army too.
Also the method by which the Amazons can challenge for the queenship.
Among the Children of the Light in The Wheel of Time, a victory in a duel conducted within the proper constraints results in the loser's rank and property being forfeited to the winner. Galad became Lord Captain Commander by using this law.
Another example would be the Aes Sedai, whose internal ranking depends partly on how strongly they can wield magic.
The Forsaken also structure their hierarchy this way; it's justified because of the fact that the Dark One likes pitting his servants against each other. The Forsaken hierarchy is pretty fluid as a result, since whoever is most successful at the moment has ascendance over the others, but Ishamael was always the overall leader both in his original body and as Moridin owing to being the setting's version of The Antichrist, and Lanfear and Demandred were usually close behind, with Graendal, Sammael, and Semirhage generally filling out the top ranks.
The wizards of the Discworld were originally like this, with wizards rising through the ranks at the Unseen University by filling the recently vacated pointy shoes of their higher-ups. This state of affairs ended when the wizards ended up appointing Mustrum Ridcully to the post of Arch-Chancellor; not only did he come down like a ton of bricks on anyone trying it in his faculty, but he was also nigh impossible to kill. The wizards mellowed down shortly after.
In The Fires of Affliction. Sir Roland Balfour's martial skill earns him the top spot on the mission to find the Mystery Cult's base. But he makes poor decisions, disregards advice from people he doesn't like, and is easily outwitted.
The urgals of the Inheritance Cycle. Their entirely social structure is based on feats of combat, meaning that if you don't win duels and raid enemies' villages, you'll never advance in society.
One other way for some of them to advance is a trial of manhood passage, where they go and kill a dangerous animal bare handed. We hear from one chieftain (who is of a larger 8-foot tall sub-species called a kull, take note), that he's the chief because during the passage he went and killed a "cave bear" while everyone else went after wolves. He also states that a cave bear was larger than an adult kull, and when we see one later we find he wasn't exaggerating.
The problem here is not so much a lack of teamwork or strategy, as that Robert Baratheon has no aptitude or interest in actually running Westeros. That, and he's surrounded by about four Manipulative Bastard wannabes.
It does seems possible that he was technically the closest non-Targaryen in the line of succession, as Robert's grandmother was a Targaryen. That being said, it doesn't appear to have played a part in the consideration of who would take the throne (though it is opined that even Eddard Stark, as first of the rebel lords in Kings Landing, could have made himself king if he wanted), as four Lords of equal prominence led the rebellion - Ed Stark, Robert Baratheon. Hoster Tully and Jon Arryn - and Robert was undeniably the leading warrior among them and principle driving force of the fight and thus the obvious choice.
Bronn deserves a point all to himself. Here is a man who rises from a common sellsword to a Lord and Knight, far rarer than most people believe in medieval settings, simply because he's really good at fighting. He even states he could maybe, probably beat Gregor Clegane, one of the most deadly men in Westeros.
The Dothraki seem to work on much the same lines; the most badass warrior calls the shots and leads the horde. Since the Dothraki are a Barbarian Tribe with less of a tendency towards political intrigue, it works better for them than it does for Westeros. The Dothraki's leadership only last as long as their Khal is strong and alive, if they are seen as weak, or are killed, they pick the next strongest warrior as their Khal.
Mance Rayder, King-Beyond-the-Wall, can also be considered this. The wildlings are notoriously individualistic and rebellious, and don't recognize lineage or any form of religious, political or legal authority, only your skill at warfare and your ability to command. To be King means you have to have beaten the other contenders, sometimes in a fight to the death.
Greatjon Umber, one of House Stark's bannermen, initially refuses to follow the young and inexperienced Robb Stark. Then Robb's direwolf bites two of his fingers off and he becomes the young lord's most loyal supporter, as well as the first man to proclaim him King in the North.
The Seguleh in the Malazan Book of the Fallen have their social hierarchy based entirely on martial skill. They were founded by an army of the First Empire after the Empire was destroyed.
It is later revealed that they have a parallel civilian hierarchy that exercises authority on all internal matters that don't pertain to the army. While the top ranks of the army act as the rulers of the nation, there seem to be other paths of advancement available to those not skilled with the sword.
Subverted in Dune. Early on, Paul earns credibility among the Fremen by reluctantly killing one who challenged him to combat. The Fremen, like the Bedouin culture they loosely parallel, have a culture that values "honor," defended through bloodshed. Also, they expect their leaders to succeed by killing their predecessors. Though the Fremen take him for a Messiah and see his leadership as inevitable, he refuses to take the place of the tribe leader Stilgar by killing him. He takes power instead after an impassioned speech deploring the idea of sacrificing a loyal and talented soldier to such a brutal custom. This compels Stilgar to step down, and the Fremen accept Paul's leadership.
In Gav Thorpe's Warhammer 40,000 story "Renegades", when Gessert demands that the members of his company paint over their insignia, so they realize they are renegades and commit themselves, one says that he is no longer authorized by the Imperium as their captain. Gessert says that if he wants to fight him, go ahead.
In Jonathan Maberry's Patient Zero, the protagonist Joe Ledger is introduced to his competitors for leadership of Echo Team and told to think outside the box; six seconds later other five candidates (vets of the Navy SEALs, Marines, Army Rangers, and Delta Force) are flat on the floor.
In the Shadowleague books, Aliana convinces Galveron that this might be true, in which case he would be most fit to be leader.
Jenna and Carum in the Great Alta Saga become king and queen of the Dales because they prove they're the best fighters in the army.
Alanna of the Tortall Universe, who is the King's Champion and has the authority of the crown when the king or queen are not present. Not to mention she has not lost a battle since her training days. King Jonathan also counts, since he is a trained knight (and was in fact Alanna's knight-master while she was a squire).
InThe Stormlight Archive, anyone who wins a Shardblade becomes a noble, regardless of birth. In fact, its possible that that's how the noble houses came about in the first place.
The Biblical Judges were military leaders of ancient Isreal (at the time a loose confederation of tribes) chosen to lead during times of war and were decided by this trope.
In Robert E. Howard's Kull / Bran Mak Morn story "Kings of the Night", Wulfhere insists that Kull fight him for the leadership. Kull, though not knowing his language, deduced it before being told.
In the Incarnations of Immortality series, in "For the Love of Evil", Hell itself is an interesting subversion. When Satan first takes control, he finds it plays this trope straight. After proving his ability, he re-organizes Hell. Interestingly, his greatest power is the destruction of demons which in a complete subversion is solely based on the demons belief and not any real ability
In Codex Alera, Citizenship requires winning a witnessed duel with an existing Citizen, marrying an existing Citizen, or being granted Citizenship by the First Lord, generally for doing something completely awesome. It's largely hereditary, but that's because furycrafting power is largely hereditary.
In Warrior Cats, BloodClan works this way. Scourge can kill a cat in one blow; he's leader. Bone is huge and also a powerful fighter; he's second in command.
A belief in this principle is the undoing of the rabbits of Efrafa in Watership Down. When the biggest, toughest, most badass rabbit you've ever seen has stood alone against your elite warriors, and then rejects an offer of surrender because his chief rabbit has ordered him to stand... well, you don't want to stick around to meet the big guy's boss.
Neatly subverted in that said Chief Rabbit is actually smaller, has a permanent leg injury, and just generally less prone to asskicking than Bigwig. Not that most of the Efrafan Owslafa stuck around to find this out—especially considering there is a bigger rabbit but who is not in command.
The MinotaurEmpire in Dragonlance is all about this trope; anyone can become Emperor so long as they defeat the previous Emperor in a ceremonial (but very real and lethal) duel, and social and legal conflicts are also often solved in the arena. This becomes a plot point in the Minotaur Wars trilogy where a new Emperor comes to power after a coup, and even though he is a much better leader sizeable chunks of the population won't follow him because he dishonorably assassinated his predecessor rather than formally duelling him.
In Larry Niven's novel Footfall, the Fithp ultimately surrender unconditionally to the Humans and join their "herd" after Wes Dawson, aboard the Fithp mothership, overpowers its commander and takes control of it. He then performs a ceremonial gesture of placing his foot on top of the submitting commander's body, becoming the ship's new "Herdmaster".
Averted in The Obsidian Trilogy where Kellen's fighting prowess earns him the respect of his commanders, but he is unable to get his greater strategic goals taken seriously until he is able to succeed in the command of a small squad.
Vorkosigan Saga is a deconstruction. The endless strife and militarism of the ruling classes are ruining the planet Barrayar until they learn to get by with a minimum of asskicking. In a way it is a Coming of Age Story for an entire society.
In one Sister Fidelma novel, King Colgu of Cashel is injured by an assassin — who isn't even trying to kill him, since under ancient Irish law a chieftain was required by law to step down if unable to physically lead his people in battle, thus making way for a rival.
Honor Harrington: In The Honor Of The Queen, the religiously conservative Graysons initially can't handle Honor's mere presence, due to their prejudice against women. They simply can't believe that a woman can in any way be capable of a military command. This changes after the planetary newsnet gets their hands on a security-camera recording of Honor decimating a small army of armed assassins who were trying to kill the planet's leader — with her bare hands. Afterwards, nobody dares question her worthiness of command, suggesting that they're following the logic of this trope.
In the Dirigent Mercenary Corps series, it's a minor plot point in the first book that officer cadets are not allowed to graduate and become officers until they've served a combat tour. Until then, they command no one and are just grunts like the enlisted men.
In Harry Harrison's The Hammer And The Cross the Ragnarssons and their father are all famous champions with a history of victorious battles behind them, and this fame allows them to attract followers. In One King's Way, Shef duels the King of Sweden to the death for the right to the throne. Truth in Television to a great extent, the Norse really were that way.
A Mage's Power: The Dragon's Lair hierarchy is built with this in mind. Proving that he can kick ass is how Eric promotes from Apprentice to Novice. At the top of each Squad is a captain more powerful than several regular members and at the top of the guild is The Dragoness, who could fight all five captains at once.
Survivors uses and deconstructs the trope. In a group with a lot of unrelated dogs, this is how they choose the alpha. The pack leader is an idiotic, occasionally cowardly racist asshole who puts his needs above the entire pack, but because he's the best fighter they can't depose him. Luckily, he leaves anyway in the fifth book, and there's some justice to be found in that he becomes the Omega of the pack he joins.
Live Action TV
In an episode of Star Trek: The Original Series, "Mirror Mirror", Kirk and a few of his bridge crew swap places with their counterparts in an alternate dimension where promotions are earned by killing your commanding officer. It's a wonder they managed to keep their Enterprise crewed by anything but a huge pile of corpses.
The Klingons would've been right at home in that universe, as they actually want their worthy successors to prove their mettle by killing them to take their place.
The Nietzscheans of Andromeda, on account of being a genetically engineered race of Social DarwinistNietzsche Wannabes, base their society on this principle. The males compete with one another to gain the females' attention and the strongest male in the Pride is the Alpha.
Stargate SG-1: The Goa'uld play it deadly straight, since the only way to become Supreme System Lord is to amass enough power to tell all the others to sit down and shut up. Since O'Neil(l) dealt Ra a nuclear sucker punch back in Stargate the other System Lords have been squabbling over who gets to fill his gold-plated shoes; whenever one seems to be getting close it's generally regarded as a bad thing.
The Narn evidently follow this trope to some degree; if a Narn is really pissed off at a higher-up, said Narn can challenge him to single combat for the position. G'Kar was challenged by a young hothead leading attacks on Centauri on the station; despite the underhanded tactics (e.g. having one of his lieutenants try to get G'Kar with a poisoned dart), G'Kar wins and manages to get something of a handle on B5's Narn population.
In the episode "Wipe-Out" of the American TV series Raven, the titular character Jonathan Raven (who is secretly a ninja) decides to infiltrate a gang of surfers. The final test to join the gang is to fight every member, one by one. He defeats every single one except the boss. After losing this fight, he innocently remarks that he must've failed the test, but the boss replies that no, he's now the second in command. Later on, however, Raven (who is actually a ninja) admits to his pal that he lost the fight to the boss on purpose, because if he had defeated the boss he would have undermined his authority, and been unable to infiltrate the gang. The gang are playing the trope straight, and Raven uses Genre Savvy to take advantage of them.
In the seventh season of Buffy the Vampire Slayer, when the group temporarily turns away from Buffy as their leader, they place Faith, who as the other Slayer is the team's second strongest member, in that role instead. This is in spite of the fact that Faith has no leadership experience whatsoever, and virtually every other character has a better claim to the leadership. Willow and Giles are smarter, and Xander is the only member of the group with actual management experience.
Buffy later regains leadership upon slaying a Turok-Han in front of them.
In Kamen Rider Kuuga, the Grongi's Gegeru game revolves around killing humans, each rank taking their turn and getting progressively stronger with rank. The winner of each tribe gets promoted to the next level, the winner of the Gegeru earns the privilege to fight the Grongi King for control of the tribe. To add to it, the king himself kills off 152 Grongi he decides are too weak to engage in the Gegeru.
In The Sopranos, while recovering from a severe gunshot wound, Tony notices that his old lieutenants don't follow his orders as readily as they used to, and he suspects that they now see him as weak. Tony responds by goading his hotheaded, musclebound bodyguard into fighting him. He kicks the everloving shit out of the much younger man in front of his entire crew, to their visible shock, then calmly walks into the bathroom and coughs up blood into the sink. No one questions his orders after that.
Perhaps the practice became outdated after 1980 or so, but if you want to hold any National Wrestling Alliance Championship at the world level, you don't just have to be good at your job in the ring, you also have be prove able to kick ass when your opponent is not cooperating with you to make it look good. Below the world level, things are more relaxed.
Ork society in Warhammer and Warhammer 40,000. "Da bigga an ork is, da more dat 'es da boss." It actually goes both ways-orks know who is their boss because the boss is bigger, but orks actually grow as a response to rising in the social hierarchy-the bosses really are bigger because you start growing when you become the boss. Orks find human social hierarchy very confusing because humans "are all 'bout da same size" and wonder how they ever decide who the boss is.
Ghazghkull Mag Uruk Thraka, the greatest of all Ork warlords, has a head the size of a human torso, and arms thicker than a literal tree trunk. He's actually closer to the size of a large Killa Kan or small Dreadnaught than a typical ork. Nothing more needs to be said about his strength, or his love of all things dakka.
Other such societies in the two settings include, but is not limited to, Norsca, Chaos warbands (especially Beastmen), Skaven, Ogres, Dark Elves and Dark Eldar.
Chaos Lord gain their position through sheer power and favor from the Gods. The latter is gained by the Chaos Lord's quality in the former. Kharn the Betrayer, for example, is the greatest of all Khorne's Champions due to his phenomenal fighting ability. When a Chaos Lord is slain, the best of the warband usually take each other on until only the strongest remain, and then the strongest fight each other so that only the greatest Champion remains.
Eldar also follows this trope; their leaders are usually ones who are lost on the path of the warrior or sorcery, so if they lived that long, you know they can kick ass.
Ogres are the embodiment of this trope. The only requirement to becoming tyrant of a particular tribe is to beat the (sometimes literal) living crap out of the old one.
Given the Eternal War nature of the setting, nearly every single faction is prone to this trope, you only make it that high in rank if you have the skills to survive. It's only subverted with the Imperial Guard and Tau, who are instead privileged to better equipment and/or a good sized command squad to make up for their leader's lack-of-asskicking - though with the Imperial Guard's myriad of different regiments within its vast totality with practices and cultures varying heavily, they may play it straight too.
In Battletech, this is pretty much how the Clans work. The warrior caste is very much in charge with everybody else ultimately working for them, martial skill determines rank and command privileges, and trial by combat is considered a legitimate way to air one's grievances or even overturn political decisions that didn't go your way.
Subverted in a very subtle fashion, rarely explicitly stated. The Clan system selects leaders based on their martial skills in single combat. It does not select on unit-level tactics, administrative skills, or leadership ability. When the Clans have fought in large-scale operations against comparable opponents (Tukkayid, Operations Bulldog and Serpent, Operation Reckless) they typically get their asses kicked.
Not entirely played straight however. The Blood of Kerensky novels make it clear that Khans (who are elected by the Clan Council) have to be able to play politics as well. Furthermore one has to be nominated (requiring connections) to be able to fight for a Bloodname (generally required to serve beyond the age of 35 and rise above the rank of Star Captain). The less successful Clans (Smoke Jaguar, Ice Hellion) tend to play this trope straight. The more powerful and thriving ones including; the Wolves, Jade Falcons, Ghost Bears, Diamond Sharks, and Star Adders for example, select leaders based off both combat ability and political prowess.
Also the drow that follow the spider goddess Lolth, which includes a great majority of the entire race. There are lots of rules in their society that demand severe punishments for betrayal and murder, but only the victims or their immediate families can bring a case before the high priestesses. Thus the only way to power is to kill everyone in your way and intimidate everyone who could make your deeds publicly known. Everything is legitimate, as long as you can get away with it.
Applies to the system as a whole. Since all abilities, from ability to fight to ability to weave baskets, are based on level, anyone that is exceptionally good at something, even a purely non violent profession or trade, is liable to be able to take at least a small army on by themselves... and win. As there is no shortage of ambition and predators - literal and figurative - those who keep a position of authority are those with enough personal power to kick the ass of anyone who wants to take their place. Often ends up being recursive with Authority equals Asskicking, both in that getting to the position in the first place is liable to improve your combat abilities (even if you do not fight your way there) and that it is often necessary to be proactive in order to maintain your position.
And let's not forget the iconic D&D joke - this is a game about breaking into creature's homes, killing them, and stealing their personal possessions. As said creatures tend to resent this, having sufficient combat ability is a job requirement.
Forgotten Realms frequently shows how such things happen. Let's take Wyvern's Spur and a story of one ex-sellsword, now the King's governor:
Giogioni Wyvernspur: Is that a prerequisite for your job?
Samtavan Sudacar: Got to make a name for yourself at court. Slew a frost giant that was terrorizing merchants in Gnoll Pass. That's how I got into politics—a service like that has to be recognized officially.
Exalted has this going on with the Yozi Cecelyne, Hell's lawmaker. Her rules stem from the belief that the strong are to rule over the weak. Her other laws are often arbitrary and sometimes outright contradictory, but this is the one truth she holds to absolutely. Indeed, it's one of her unbreakable themes as a Primordial being, so she can't even conceive of another way it could be.
The Vikings of Fate of the Norns: Ragnarok live in a time when every little problem or power struggle escalates very quickly. As a result, people in power have to be able to kick a lot of ass if they want to stay (case in point: King Erik BloodAxe murdered almost every single one of his brothers to keep his place).
In Apocalypse World it's very difficult to become a leader without being a very good fighter. The Chopper and Hardholder classes even have moves letting them use the same stat for exercising authority and kicking ass.
In Halo, the Elite hierarchy is simple enough: the more enemies you kill, the higher your rank.
The Brutes take this even further; just challenge the current Chieftain of a tribe to single combat, kill him, and you get to be the new one.
Although he's only a non-com in rank, nobody, not even the brass, really ever says "no" to the Master Chief. Thankfully for them, he's also the type to follow orders.
Lasky: At ease, Chief. Feels kinda odd for you to call me "sir."
In World of Warcraft, Ogre hierarchy is based solely on asskicking. Basically, rank and gear go towards whoever can fight for it, since Ogres lack the mental capacity to elect someone democratically.
Notably, in the Dire Maul dungeon players can be declared king(s) of the Dire Maul Ogres by killing the current king (who earned his title by declaring himself king and killing anyone who challenged him). Doing so without killing any of his lieutenants is a Self-Imposed Challenge that has a chance of dropping epic level gear.
Also, the now-abolished honor ranking system lived and breathed this trope: The Grand Marshal and High Warlord ranks were awarded to characters who week after week were the most lethal among their respective factions. In practice, this required nearly nonstop combat for several months.
The tribal Horde races (orcs, tauren and trolls) all seem to be this. It's been stated many times that the leaders of tribes are the most powerful warriors in the tribe (or, in the case of trolls, most powerful witch doctors).
In the Warlords of Draenor expansion, this happens to a Living Legend reknowned for their ability to take names—your character, who gets put in charge of a garrison established in Shadowmoon Valley (for Alliance) or Frostfire Ridge (for Horde) specifically because of your personal strength and power, not to mention the people you've helped and the evil mobs you've taken down over the course of playing the game.
Cosmetically happens in StarCraft II. Every terran unit starts as a Private, then increases in rank depending on how many kills they scored. Zerg and Protoss do the same, but with different titles. Heroes always have a set rank, though.
The Zuul from Sword of the Stars operate on this mentality. They are a Hive Mind, so the strongest personality directs the collective... Until it shows weakness, at which point all the ones who can challenge it will do so.
Overlords in the Nippon Ichiverse. The title of Overlord of a Netherworld will automatically pass from the defeated to the victor if its possessor is defeated; thus, only the strongest demons (or those who can fool their fellows into thinking they're far stronger than they really are) remain Overlords.
Anyone can become a demon Overlord if he or she kicks enough ass. This (canonically!) happens to Prier from La Pucelle Tactics after she defeats too many demons in the Netherworld. The demons pledge their loyalty to her and declare her to be a Demon Overlord, much to her dismay.
Justified as the Laguz kingdoms were founded by rebel slaves: quite logically, they chose as leaders the ones who could beat up the most easily the people who held the whips, and the tradition stuck
The Thraddash of Star Control 2 are willing to reshape their society along your very whims once you've killed about a third of their military. Their history is a series of numerically ordered Cultures, each one defeating the previous one in total war. They've nuked themselves back to the stone age five times, and each culture considers itself the strongest due to this tradition. Kick enough ass and you're in charge of everything.
During the 65 Million B.C. section in Chrono Trigger, Ayla (chief of the Ioka tribe) explains that whoever's strongest is the chief. She makes sure Kino, the second-strongest person in the tribe, is out of danger whenever she's about to do something heroic, just to make sure the line of succession is undamaged. (Well, that and she loves him.)
In Mass Effect, the most badass krogan around is the leader. Wrex is well on his way to becoming the lord of the krogan, and he killed a thresher maw on foot. Shepard briefly wonders why in such a warriorlike race someone would choose to become an ambassador. The answer? He (the ambassador) is the strongest warrior in the clan and therefore gives the best impression of his clan's strength.
After going through the Krogan Rite-Of-Passage together and being the first to kill a Thresher Maw on foot since Wrex, it says a lot when Grunt declares that he considers Shepard to be their Battlemaster.
Spectres. "Individuals forged in the fire of service and battle, those whose actions elevate them above the rank and file." Basically, if you're Badass enough, you get to be Judge, Jury, and Executioner.
All the crazy stunts that Shepard's original crew members pulled off under him/her finally begin to pay off authority-wise in Mass Effect 3 (except for Wrex, who gets his authority in the second game): Ashley/Kaidan is promoted to Lieutenant-Commander/Major, respectively, and appointed the second human Spectre (after Shepard), Garrus gets pretty high up within the Turian Hierarchy (high enough that he's saluted by generals), Tali is an Admiral (and that's as high as you can go on the Flotilla), and Liara is the new Shadow Broker (though that was more of a case of You Kill It, You Bought It).
In The Godfather game, you progress up the ranks of the Corleone family by completing missions for them and gain Respect levels mostly by killing a lot. A real lot.
In the Neverwinter Nights 2: Mask of the Betrayer expansion pack, the player can become the Jarl, or leader, of a tribe of Frost Giants by competing in a trial of strength, namely that whoever's the last man standing and holding the crown, they become the head. The player can even take this to extreme lengths by throwing all the Frost Giants out of the tribe and exiling them.
Final Fantasy VI: Cyan Garamonde is a variation in that his outstanding fighting skills have made him highly respected by his fellow soldiers, although he doesn't seem to wield any actual political power.
There's a damn good reason Ridley is the leader of the Space Pirates.
In Tropico when you decide how your character became El Presidente, a military coupe is an option.
Dragon Age. In Origins, if Sten is in your party when you enter a specific village, he becomes annoyed with your behavior and challenges you to a fight. Beating him increases his respect for your leadership.
This only happens if his approval is below a certain level. If he already has a high approval of you, he simply expresses his concerns, but does not fight you.
And in Awakening, The Warden is so respected for stopping the Blight and killing the Archdemon that they are promoted to Warden-Commander of all of Ferelden and get lands and their very own keep.
That's also how the Tevinter Imperium raised to prominence and how it fell: the most powerful mages became its ruling class, slaughtered everyone in Thedas who was strong/proud enough to stand up against them and enslaved the rest, remaining the sole masters of the continent for centuries. While the Blight weakened it, the coup de grâce came from Andraste, which, depending on the version, was either God's wife or a mage so freakingly powerful that it made the Tevinter Magisters look weak by comparison. Whatever the cause, an army of fanatical zealots and rebel slaves formed around her, and the Chantry founded in her name became the new dominant force in Thedas.
Fenris from the sequel claims that Tevinter is still operating this way. He claims that this means all of the magisters practice Blood Magic even though they officially condemn it like everyone else since Blood Magic is too powerful an advantage to ignore. The magisters have no qualms about enslaving other mages who can't resist Blood Magic.
In Dragon Age II we have Hawke, a former-refugee from Ferelden who became the Champion of Kirkwall after years of ass-kicking culminating in stopping a major threat to the city. In most versions, this involves fighting the Arishok in single combat. This is even more apt when the Mage Hawke has even Knight-Commander Meredith of the Templar Order, who hunts illegal mages having to tip-toe around Hawke with kid-gloves. Even a non-Mage Hawke is implied to have enough authority that the Templars purposefully choose to ignore Anders and Merrill, two of Hawke's well-known Mage friends because of this.
In Liberal Crime Squad, authority is represented by how many people you can have to work under you. That value depends on Juice. And one of the ways you can gain juice is by fighting conservatives.
In Star Wars: The Old RepublicThe Sith Emperor is in every way deserving in his position, being a being with such connection the dark side his power is near godly. So much so he single-handedly captured Revan and killed the Jedi Exile, two godly force users in their own right.
Codified into rule in the Book of Mages games. When the old Great Mage dies, an "election" is held, and whatever mage can defeat all challengers is elected Great Mage. In The Dark Times, this system breaks down; the Black Robes hold an election among themselves and refuse to allow non-Black Robes to participate, while the White Robes expressly reject the system, and their senior members elect a White Mage based on his reputation. A faction of neutral mages, who hold to the letter of the law, attempt to uphold the rules against whoever wins the war and play the trope straight.
In Disgaea this is pretty much how the Netherworld works, power is the only things that demons respect. Whoever defeats the current Overlord/Dean/President becomes the new one or they can appoint someone of their choice.
"There is one law in Valhalla. The weak shall serve the strong."
In Kingdoms of Amalur: Reckoning, two of the Factions work like this. The House of Valor arena celebrates martial strength and conflict and is always passed down to whoever can defeat the current Champion of the House. The Scholia Arcana also works on this principle since the Archsage is always chosen based on his/her mastery of battle magic. This is because the Scholia Arcana's true purpose — a secret that is passed down from Archsage to Archsage — is to watch over the Dark Empyrean's prison. The Archsage must fight the Dark Empyrean if she ever breaks free.
Winning the King of Iron Fist Tournament gives you complete control of the Mishima-Zaibatsu in Tekken.
In The Elder Scrolls III: Morrowind, there are a few guilds and factions which operate on this, but in particular is Great House Telvanni. It's a faction of mostly Evil Sorcerers who strongly believe in Might Makes Right and allow Klingon Promotion as a perfectly legal means of increasing your status within the house. As part of the main quest, in order to be named Telvanni Hortator, you're allowed to simply kill every councilor except for the one needed to actually name your Hortator, and wisely, that councilor will give you his vote with no strings attached.
In The Elder Scrolls V: Skyrim, this is how dragon hierarchy works. If there's a question of pecking order, a fight ensues. A dragon either wins, submits, or dies. Alduinthe World Eater, supposedly the mightiest of all dragons, runs away like a Dirty Coward after the Dragonborn beat him the first time, claiming he's going to gorge himself on souls of the recently dead in Sovngarde. This flight is what causes a number of dragons to question Alduin's lordship, and one of them to actually defect to your side. After you destroy Alduin for good, you get a scene of all the dragons bowing to your supremacy.
In Xenonauts, soldiers are promoted to higher ranks based on the number of skill upgrades they achieve through training. And since the training consists solely of killing alien invaders...
Wolf is about simulating the life of a wolf. If you want to be alpha (and thus have breeding rights), you're going to need to whip every wolf who thinks they can take you.
In Crusader Kings gavelkindnote lands are split among all possible heirs succession often ends up working like this in the ensuing Succession Crisis. It helps that many of the cultures that favor that method are in the real life section.
The closest thing to a government body seen in the mainstream Pokémon games is the Pokémon League, whose leader is the Champion, recognized as the region's strongest Trainer.
In The Adventures of Dr. McNinja one villain has a plan to take over the presidency by convincing Americans that it works this way. The arc ends with the good doctor pointing out all the many flaws in the plan.
There's also the quicker way to become the supreme leader of a rather large army.
Similarly, The Bandit King set up his band of bandits with this as a rule. Unfortunately for him, his daughter, a sorcerer, grew up to be more powerful than he was.
In Dan and Mab's Furry Adventures , this is the basis for most Creatures' system of (ahem) ethics. On the brighter side, it means revenge is pretty rare, since, by such logic, if you were defeated, you deserved to be.
In S.S.D.D this is the basic principle of the Collective of Anarchist States' hierarchy, though most challenges are non-violent, a lower ranking Advisor is promoted if he challenges a superior's decisions and gets a better result. The CORE is a bit more Authority Equals Asskicking due to their use of cybernetic implants.
In TwoKinds the Basitin operate on this principle, after the three generals are killed the succession is largely decided by means of duels, and the king is nearly eight feet tall, in a species that is rarely more than 5'5".
In The Gamers Alliance, the strongest and/or most cunning demons end up in leadership positions in the hordes. Anyone can challenge the current leader of any tier, and if the previous holder of the title is defeated, the victor takes the title.
The Predacons in Beast Wars seem to operate on this principle - when Optimus Primal is kidnapped by the Vok, turncoat Dinobot insists that he should lead the Maximals because he's the strongest. Unfortunately for his ambitions, Maximals elect their leaders by secret ballot.
Their ancestors (the normal evil faction), the Decepticons, make this policy very explicit. Since the entire faction is made up of vicious murderers, the only leader who'll survive is one strong and smart enough to terrify them into submission.
This is repeated with the Predacons in Transformers Prime: Predacons Rising. Darksteel and Skylynx refuse to follow Predaking until he hands them their skidplates.
The Powerpuff Girls episode "Impeach Fuzz" has the Mayor ousted from office by Fuzzy Lumpkins. He beats him in a wrestling match to regain control. Granted, this was Fuzzy's idea.
The TMNT episode "The People's Choice" involves two aliens whose electoral process involves combat with the current ruler. Donatello remarks that our electoral process is more peaceful, with Raphael adding "most of the time."
In ThunderCats (2011), this is the ethos of the Catfolk-populated kingdom of Thundera, who style their ThunderCats as the bringers of "law and order to a world of warring Animals" assuming that only their race is the one "strong enough to maintain this fragile peace!" This culture is reflected in Old Soldier Panthro's refusal to accept young king Lion-O as his liege until Lion-O has proven his prowess with the Sword of Omens.
The Society For Creative Anachronism holds crown tourneys every six months where people fight in armored combat to determine who shall be the next king or queen of their kingdom.
This is Truth in Television for a major part of human history. Many leaders came into power by kicking out the region's current leader, then doing the same to anyone who might try to challenge them later. (Although it's usually the army doing the asskicking rather than the individual leader.)
It is said that when Alexander the Great was asked to whom the succession would go, he replied "to the strongest." note This may actually be the product of Self-Serving Memory by those who witnessed his death. The most logical successor of Alexander was named Krater'oi, but he was not there when he passed away. Those who were claimed Alexander had said that he left his empire to 'krat'eroi' (the strongest), with the only difference being the placement of the accented vowel. Krater'oi initially submitted to Perdiccas, who became regent of Alexander's son in the court intrigues that followed, but then Krater'oi was killed in a rebellion apparently started by Perdiccas' marrying Alexander's sister in a bid for power.. Of course no one ever figured out who was the strongest until the Romans came along and showed everyone, thus becoming The Empire.
Along the Scottish Border that was pretty much how the clans worked too. See The Steel Bonnets
Attila the Hun was the leader of the Huns because he was the strongest of them all.
In ancient Ireland, chieftains were required to be of sound body — if a king lost his arm or leg, he was expected to step down, since obviously he could not lead his armies or protect his people.
Pick any animal species organized by packs or herds, and their social order will generally be ranked accordingly, with the strongest male exerting the most influence, both with regards to the pack as a whole, and with regards to the available females.
The term "pecking order", in fact, originates from hens. Yes, even female chickens will fight to establish dominance. The alpha hen in a flock will frequently pull out the feathers of lower-ranked hens, often drawing blood. And since they usually attack the head, pecking out of subordinate hens' eyes is not unknown.
Wolves and lions are both widely known for their respective social structures.
Though atypical, this can even happen with domestic dogs: If their owner fails to establish authority by the dog's standards, the dog may declare themselves "pack leader" and refuse to be trained.
The Leader of any horse herd is the dominant mare. She chooses routes and takes the best drinking/feeding. The stallion's role is to drive stragglers along and stay at the edges, guarding against threats. Taking down threat after threat wears on the stallion. Sometimes he'll allow a younger stallion to join him, though it means he'll eventually be displaced, thus making for a sith apprenticeship.
Warrant Officers in the United States military are part this and part Genius Bruiser. You get to be a warrant officer by being more skilled in your Military Occupational Specialty than an E-9 (highest ranking enlisted) in that specialty is supposed to be. Unlike regular commissioned officers, warrant officers don't need college degrees (though many have them anyway). Although outranked by regular commissioned officers, they still rate salutes from enlisted members, and can even be made company commanders in specialty units.
Among the Ijaw clans of southern Nigeria, the cultural period before the rise of war-canoe houses and kingship (dated usually as 17th Century) is known as the "Heroic" or "Warlord" period. Basically, clans rallied behind strong fighters who organised them along war-making lines (levies of warriors from each family, garrisons). The top warriors in each clan ruled in council under the strongman, who could be deposed for failure in warfare, or a challenge to single combat. Many of the founding warlords have been elevated to deity status, becoming "patron saints" of combat and national cult heroes for their clans (Fenibeso for Okrika, Egbesu for many of the central Ijaws).
Democratic Elections are (sometimes) a more civilized form of this. When you think about it they are a non-violent Combat by Champion involving an exchange of insults until the one whose reputation has been least destroyed gets the privilege of taking office and being blamed for all the evils of the world for his entire term. In any case it is about giving power to the one who was victorious in a contest.
This trope is a nice summation of the fascist worldview. In the 1930s and '40s, when it was also sometimes referred to as "Realism" in relation to foreign policy, Orwell summed it up with a supposed quote from Germany's "Iron Chancellor" Bismark: when asked if a failure in foreign policy had been caused by being too harsh to a defeated enemy, Bismark was supposed to have replied "No, it was clearly caused because we weren't harsh enough".
William Marshall was one of the most important English military commanders and at the end of his life the regent of the kingdom. While his father and elder brother had held the office of Marshall, he was sent to France as a child, where he eventually became one of the greatest champions in knight tournaments. He first got a foot into politics when he was chosen as the personal coach for the son of the king of England, because he was the greatest fighter in all of Europe! Even in his 70s he still fought in major battles, which probably helped him a lot in being chosen as the regent for the infant king after the death of King John.
This was how Henry IV, Edward IV, and Henry VII became King of England, securing their throne on the battlefield and eliminating opponents through violence.