Badass Normal/Tabletop Games

Board Games

 * The Imperial Guard of the Warhammer 40,000 universe, consisting of ordinary men and women, regularly take on all varieties of horrific Aliens and Monsters, including swarms of alien locusts like the Tyranids, hordes of Orks, the endless legions of the lost and the damned, backed by gibbering daemons and power-armoured Chaos Space Marines, the Necrons - an undead, implacable race of zombie robots - and technologically advanced Eldar, with little more than a flak jacket, a lasgun, and gigantic balls of steel. And they sometimes win.
 * The Tanith First and Only from Dan Abnett's Gaunt's Ghosts line of Warhammer 40,000 novels. They're just as squishy as any other Guard regiment, yet that doesn't stop them from pulling off feats that would get other Imperial Guard units annihilated. Most of these feats consist of winning against vastly superior numbers of Chaos forces. Individual characters and squads have been known to kill all sorts of things that could easily wipe away enemies and units that could potentially destroy entire armies of Imperial Guardsmen all by themselves. These include, but are not limited to: numerous Chaos warlords, a Dark Eldar assassin, high-level psykers, a Chaos Dreadnought, and an entire squad of Chaos Space Marines.
 * This is made even more impressive because the Ghosts are NOT a standard Guard regiment - they're LIGHT INFANTRY. No tanks, no artillery, and less body armour than most other regiments. They're actually MORE squishy than most of the already quite squishy Imperial Guard. Ironically, since their specialties lie in the stealth and dirty tricks department, having less armour (and a colossal dose of badass) has actually made them more survivable.
 * Ciaphas Cain, HERO OF THE IMPERIUM!, in Sandy Mitchell's novels, who has managed to defeat everything from psykers and Greater Daemons of Slaanesh to Necron warriors, Dark Eldar Reavers, an Ork Warboss, Khornate Berserkers, and Tyranid Hive Tyrants, Broodlords, and Genestealers, along with countless mooks and minions of all of the above.
 * He does generally outwit them first, and his ultimate goal is to not be fighting at all; he just fights with the desperation of a cornered rat.
 * His motives don't change the fact that several of those victories (an Ork Warboss, a great many Genestealers, two and a half Khornate Berserkers (one was killed by Jurgen with his trusty meltagun, but Cain still fought it to a stand still) and the Greater Daemon of Slannesh) were in single combat and all he had was a laspistol and chainsword. He's also taken on at least one Inquisitor and managed to live long enough for reinforcements to arrive.
 * He's described by Vail to be one of the best marksmen and duelists she's ever known. Coming from an Inquisitor, that's extremely high praise.
 * Commissar Yarrick, a perfectly human man who had his arm torn off by a massive Ork warlord and responded by tearing off said Ork's own cyborg arm, attaching it to himself, killing the hell out of the Ork and leading his army to victory before allowing himself to pass out. And he's only got harder since then.
 * This is a man who, upon hearing that his enemies were so afraid of him that they believed he could kill them with an angry glare, replaced his eye with a laser so that he could actually do so.
 * Ghazghkull Mag Uruk Thraka considers Yarrick to be a Worthy Opponent. As in, the largest and most influential Ork in the entire galaxy who has personally led two of the largest and most destructive Ork WAAAGH!s in Imperial history considers a "skwishy humie" to be as good as him. That, ladies and gentlemen, is this trope.
 * Another note on Yarrick and the Orks: Yarrick is so Badass, that the Orks, an army of Ax Crazy Blood Knight Chaotic Stupid Fearless Fools, are utterly terrified of him. The problem is, most Orks think Yarrick is an unkillable badass and their belief actually makes Yarrick an unkillable badass. On the tabletop, if Yarrick is killed by Orks, there is a good chance he will get back up.
 * In the related video game, La'Kais probably qualifies as well. Sure he's an alien, but he's a Tau, which means he's shorter lived and physically weaker than even the average human. And yet, according to the One-Man Army page, on his first day of live fire combat, he personally killed "several battalions of the Imperial Guard, large numbers of Space Marines and several Dreadnaughts, a good deal of Chaos Marines and several Daemons, and he does it all within the timespan of twenty four hours." Alas, he breaks down after that.
 * The Tau in general managed to survive an Imperial crusade, a Tyranid splinter fleet, defeated an Ork WAAAGH! and supposedly killed a daemon prince. The last in particular is quite an accomplishment since killing a daemon prince without the proper warp killing tools at hand is still an admirable effort.
 * As for the daemon prince, it might have helped that the Tau have no warp presence whatsoever.
 * Actually, the Tau's lack of warp presence merely prevents them from being corrupted by it's influence. Daemons are still capable of killing Tau quite handily. Still, the Tau are one of the most dangerous opponents to Chaos forces because Chaos are forced to fight them head-on, rather than simply influencing members of their society and bringing them down from the inside.
 * Although no longer canon, there is probably the biggest example in 40k, Ollianus Pious, a Guardsman that decided to fight a stupidly powerful being that was already at demi-god status before the Chaos Gods decided to use him as a recepticle for all of their power. He was swiftly killed for his troubles, but damn.
 * The Horus Heresy novels also contain a fair amount of them. The one that stands out particularly was the mute bodyguard Maggrad, who was by the standards of ANY universe containing Space Marines, an extremely proficient killer. This was further emphasized later when he was able to almost best an extremely experienced Space Marine captain. Dinas Chayne, another bodyguard, was also an incredibly talented soldier who was, even more amazingly, capable of briefly matching a Primarch in term of swordplay. Many of the Imperial Army soldiers of the era were also pretty badass.
 * Maggrad, having fought waves of mutants to a standstill to protect his charge, is actually congratulated personally by Horus. The giant, superhuman, galaxy-bestriding Primarch and Emperor's favourite who he practically worships actually tells Maggrad that he admires him. Cue the closest thing to Squee in Maggrad's life.
 * Guardsman Hawke. In Graham McNeill's Storm of Iron, he escapes the initial assault (blowing away a couple of Chaos Space Marines with an assault cannon as he does), hoofs it to an orbital torpedo silo, and takes out half of the Iron Warriors Chaos Space Marines besieging the Citadel. He's also the only Imperial to survive the whole war, not counting slaves hauled off to Medrengard. To put that in perspective, he had been written off by his superiors as a useless, foul-mouthed, insubordinate and ill-disciplined Guardsman barely worthy of the name prior to the attack.
 * While not ENTIRELY powerless, the Sisters of Battle do qualify to some extent as they outright shun most of the more common ways to gain power in the Imperium in favor of purity.
 * The Catachans, being born on a planet that tries to kill you every minute you live and breath makes sure the only ones to survive are this trope.
 * The armies of the Empire in Warhammer Fantasy Battle. They fight the same daemonic hordes, massive armored followers of Chaos, and their less superpowered allies as their 40k counterparts. They don't have lasers, aircraft, tanks, Space Marine backup, or howitzers. They hold the line with plain steel armor, swords, and occasionally matchlock muskets.

Card Games

 * Mitos y Leyendas takes this up to eleven with the "Heroes" set, which is based off the War of the Pacific. As a result, ship captains are on the same tiers as Top gods
 * In Magic: The Gathering humans tend to be this, especially white mana humans. In the Gothic themed Innistrad block, White Humans decks repeatedly came in second. They were able to band together and overcome Vampires, Werewolves, Mages, Zombies with little more than the power of teamwork and the grace of God.

Tabletop RPG

 * Any high point GURPS Character will be this, if they didn't load up on lots of fancy exotic advantages.
 * Pretty much any high-level martial character in any edition of Dungeons & Dragons. Fighters? Yes. Warlords/Marshals? Yes. Rangers? Yes. Barbarians? Yes. Rogues? HELL yes. Barbarian/Fighter/Frenzied Berserker? OHSHI--
 * In 4.0 there is an epic destiny for Rangers and Rogues called Godhunter. So yes, your halfling armed with shurikens and a dagger may in fact one day murder Tiamat.
 * Why stop just there? In 4th edition, there are 14 Epic Destinies, counting the Godhunter, restricted to Martial characters alone (that is, Fighters, Rangers, Rogues and Warlords -- Barbarians are Primal in 4e). The Adamantine Soldier is a Fighter or Warlord who has become such a master of heavy armor that they are Nigh Invulnerable; nothing hurts them, nothing can get past them, and they will never be broken in body or spirit. The Beastlord is a beastmaster Ranger who becomes so close to his animal companion that they become a single mind and soul. The Dark Wanderer is a Rogue or Ranger who has wandered so long and so far that they have outrun fate itself. The Eternal Defender is a Fighter who becomes an immovable object in battle, whose courage and duty leads to them taking up arms to protect the world or even The Multiverse for all eternity. The Legendary General is a Warlord who goes on to fight in the greatest battles the planes have ever seen, and if they so desire, may conquer all of reality itself. The Martial Archetype is a multiclassed Martial character who bcomes the ultimate warrior. The Perfect Assassin is a Rogue so skilled at dealing death that even Death itself will not dare to approach them before the Perfect Assassin is ready to die -- they may even slay the God of Death and take the throne for themselves. The Undying Warrior is the ultimate Fighter, immortal and unkillable. The Warmaster is a Warlord who becomes so skilled that there is no challenge left in reality -- defeating armies of demons or outwitting the gods themselves becomes trite, forcing them to seek the Eternal War, the mythical arena where all of the greatest military leaders who have ever lived spend eternity testing their skills against each other. The Dragonheart is a Martial character who reveres dragons as the ultimate embodiment of martial virtue, devoting themselves to those concepts with such fervors that they transcend their original nature and become dragons in body and soul. The Invincible Vanguard is a Martial character is a warrior who yearns to face the greatest threats ever, and who goes on to defeat them all. The Legendary Sovereign is a Fighter, Ranger or Warlord who goes on to found a kingdom, or perhaps an empire, that will never be forgotten. And the Star-Favored Champion is destined to become, simply, one of the greatest heroes ever known. And each and every last one of these characters has no special gimmicks, no magic, nothing at all mystical. They are just. That. Badass.
 * In the New World of Darkness, the Hunters from Hunter: The Vigil are (for the most part) the ordinary humans who take on the supernatural. And then there are the Slashers, humans that can be just as dangerous as horrors...
 * The Sourcebook "Mirrors" introduces the Extraordinary Mortals template, which gives characters access to "Skill Tricks", specialized abilities within their mundane Skills. The best of these verge on Charles Atlas Superpower.
 * Mutants and Masterminds is explicitly designed so that these can compete with ultra-powerful wizards and Nigh Invulnerable aliens from Xenon.
 * In Deadlands, any player character who isn't a Huckster or one of the Blessed has to be this. They're expected to go toe-to-toe with Native American demons, Steampunk Mad Scientists, walking corpses, Evil Sorcerers, and, and are typically armed with nothing more than a Colt revolver, a Badass Longcoat, and a mean disposition.
 * Any of the non-super OOC from Rifts, but in particular the Rogue Scholar. For people whose sole class ability is "Knowledge is Power", they sure do have quite a reputation with the Coalition. And by reputation I mean "KILL HIM NOW! Now, HE'S the biggest threat!"
 * Iron Heroes basically thrives on this, with 9 out of 10 classes having no magical talent at all. Even the magical one could half-fulfill this trope, since spellcasting could horribly backfire and they tend to learn how to fight with weapons anyway.