While most Tabletop RPGs have some kind of wound penalties, Dungeons & Dragons does not, thus ensuring that any character with at least one hit point remaining (and several without that) is capable of any kind of action and exertion. This is Handwaved in some editions by the claim that hit points don't actually represent health, but the "ability to avoid injury" (despite the fact that they are recovered through bandages and magical curing spells). This, of course, inspired on RPG.net Fauxtivational Posters of bloodied and beaten (but still standing) characters with a caption of "I've still got one HP left!" (Or of Monty Python's Black Knight, captioned "Anything over 0 means I'm good to go, baby!")
In 3rd Edition you aren't dead until you reach -10 hp. At 0 hp you are disabled, and will lose HP with any action except movement that doesn't heal you. At -1 to -9, you are dying, meaning you fall unconscious and begin bleeding out at a rate of 1 hp per turn (unless you have an ability like Die Hard) unless healed or you reach -10 hp. You recover completely if you are taken out of negative hp via magical or mundane healing—if you aren't dying but you are still in negative hp, you remain unconscious; any healing stabilizes you.
Due to this, a common set of House Rules is to have characters die after being dealt a truly massive amount of damage. (3.5 does have "Death by massive damage" rules - any hit that deals over 50 damage needs a fort save)
Even funnier when a character with the Delay Death spell and -1000 HP or so gets tossed into an Antimagic Field.
Or when you take a Barbarian with a character option that explicitly says you do not die, no matter how deep into negative integers you go, so long as you are still fighting and still raging.
This originated in the Dungeon Master's Guide in 1st Edition. CPR or bandaging wounds would bring a dying character back to 0 HP, and the character would need to rest for many weeks after to be able to fight again.
Oddly enough, all other tomes in the 1st Edition stated that at 0 HP the character was dead.
Also, drowning immediately sets your HP to zero. There are at least three ways to exploit this. One of them involves transfinite numbers.
The 4th edition finally bites the bullet and takes the handwave to its logical conclusion; healing spells and bandages still recover hit points, but so do stirring speeches, special fighting moves, and even just taking a moment to catch your breath.
In 4th edition, you are unconscious and bleeding out at -1 HP or below, you are critically injured; you need to roll a save every turn to not die. If you are healed at all, your HP is set to 0 before healing, the same if you are stabilized. If you fail 3 saves, you are dead, and have to be resurrected. Now where did I put my 5,000GP in diamonds...?
When a PC goes down in 4e, no one knows if he is critically injured or Not Quite Dead. If his death saves run out, he was bleeding out the whole time. If he gets healing or rolls a nat 20, then the injury was Only a Flesh Wound
Worth noting that in 4E a character down to half-health or less is considered 'bloodied'. This has no effect in and of itself, but many abilities will have different effects on (or by) bloodied targets. Dragonborn characters gain an attack bonus when bloodied; Tieflings gain an attack bonus against bloodied enemies; there are several attacks that do more damage against bloodied foes; there are several ways to regenerate or self-heal that only work when you're bloodied. Also, many monsters have attacks that automatically activate when they are bloodied.
Pathfinder Oracles can more literally do this to other people; one of the mysteries they can study is Time, which gives them access to a revelation ability that removes targets from spacetime altogether for a number of rounds if the target fails their Fortitude save.
GURPS is notable for completely averting this trope by including shock penalties for every landed attack, specific rules for dismemberment and allowing characters to survive down to -5xHP as long as they make HT rolls at -1, -2, -3 and -4xHP. In fact the rules note that it is only as -10xHP that there is nothing left of the character.
In addition, it's possible to perform called shots (by taking penalties to the roll) so that you can shoot (or stab) someone in the vitals (for extra damage) or in a limb (where a given amount of damage will cripple that limb). Note that the above-mentioned dismemberment rules are basically an extension of crippling rules—usually for use with really sharp blades.
Averted in some d20-based Tabletop RPGs, most notably Star Wars d20 (the Revised Core Rulebook edition), as well as Spycraft and its derivee, the Stargate SG-1 RPG. Hit points are split into vitality points, which represent the type of damage a character can shrug off relatively easily, and wound points, which represent serious injury. After running out of vitality points, the character is fatigued, suffers ability penalties and cannot run, but is still alive, and further attacks will damage wound points. (Vitality points increase with level; wound points do not.) Only after running out of wound points does a Critical Existence Failure occur. Some types of damage, like fall damage, affect wound points directly and ignore vitality points, as do critical hits. So if you roll well, it's entirely possible for a first-level character to one-shot Darth Vader.
The Saga Edition of the d20-based Star Wars RPG would use hit points (for characters, vehicles, structures and objects alike), but both a damage threshold and a condition track. (Do damage equal to or greater than the damage threshold, the recipient moves down one step on the condition track, with a corresponding penalty to certain rolls: -1, -2, -5, -10, and then unconscious or unwilling-to-fight/resist.) Your character becomes unconscious if the damage is below its damage threshold, and killed or destroyed if the damage is equal to or greater than its damage threshold. An explanation in one of the preview articles was essentially that every blow failed to be serious or connect... except the one that dropped you to zero hit points.
Very averted in Unknown Armies—instead of players keeping track of hitpoints, they are tallied by the GM, who then describes the players' injuries back to them. Each injury must deal at least one hit point naturally, regardless of first aid, and heavy damage leaves permanent skill penalties.
Completely averted in Ars Magica 5th edition. There, every wound a character sustains imposes penalties on rolls, by an amount determined by the severity of the wound. Since you roll for everything, including defense, each wound makes it more likely that the next attack will kill/KO you, and it gets harder and harder to hit your opponent. And after a fight, even the lightest injuries have a chance of becoming worse through infection unless medically/magically treated.
Averted in Cyberpunk 2020, where the more damage your character takes, the higher both the penalties to what he/she can do and the chances to end up unconscious and -especially- die are, being the latter something that given how it's designed that game is quite easy.
Averted in Inquisitor—unless armour totally stops damage to a body part there are repercussions, both immediate and long-lasting. For example, a minimum-damage wound to the head will still cause minor stunning, whereas a heavy shot to the groin will knock them prone, stun them, make them bleed heavily, slow them down and possibly send them into system shock. The only chance of not having a negative effect is taking a weak hit to a limb (you can shrug off the first few points of arm or leg damage), but anything more than a graze will cause bad things to happen. And that's before you factor in blacking out from accumulated pain, or simply having them go Totally Batshit Crazy due to post-traumatic stress. And due to having their scrotum turned into steak tartare.
This system originated with Inquisitor's ancestor, Warhammer Fantasy Roleplay, in which, yes, you can get hit with a spear in the groin and be taken out of action for weeks despite having wounds left.
Not like Inquisitor is realistic in any other factor; the only way to die is via headshot or massive damage, and it generally takes dozens of shots to inflict massive damage. Heck, you can shoot a Space Marine in the head with an anti-tank gun and he'll only have a 1/70 chance of dying.
Still, played straight(at least partially) in its successor, Dark Heresy (and its sibling Rogue Trader) - you can take good amount of damage without any ill effects(apart from having problems with healing it back), but as soon as you've lost the last wound, each wounding hit makes yet more nasty things with you. And of course, there's no difference if you're hit in the head, or leg, while you still have more than zero wounds - apart from difference in armour on those locations(see usual Warhammer "no helmet" problem).
Shadowrun averts this, adding increasing wound penalties to all actions after the character is down to about half health.
Averted in BattleTech, a sci-fi miniatures game. As your 'Mechs (huge bipedal war machines of death) take damage, they can lose weapons, take engine hits, their gyros can be disrupted, and quite realistically the pilot can be killed with a headshot. Ammunition can also explode, critical heat sinks destroyed...whenever a 'Mech runs out of armor in a location, bad things happen.
The pilot hitpoint system seems to play it straight at first, until you get to the consciousness system. As you take damage, it becomes easier for your pilot to slip into unconsciousness. So while you can technically fight at full power with only one HP left, you'll probably fall unconscious long before that happens.
Played straight with Powered Armor units, however. You can strip all the armor off a trooper, but until you take out that last damage box representing the trooper himself, he fights at full power.
Averted in Mutants & Masterminds, which doesn't even haveHit Points. More specifically, you make a special toughness save to avoid damage, with failed saves imposing a penalty on future saves. Characters who fail by a large enough margin are staggered, crippling them to the point where they can only take one action per round. Characters who hit the staggered threshold twice are immediately defeated.
Somewhat subverted in most Sanguine Productions RPGs, notably Ironclaw and Albedo. There are hitpoints in Ironclaw, but take too many wounds and you have to start rolling checks against blacking out, and you can die with only six wounds if you fail a death test. Albedo doesn't have hitpoints and instead has threshold checks to see if you die, or take body point damage.
Promethean: The Created plays it straight to emphasize the rampaging engine of destruction a Promethean can easily become. They take no penalties from damage, and unlike other supernatural creatures, do not risk falling unconscious when all their Health Levels are filled with damage, fighting to the very death. And if they do die, they can come back.
Justified, however in Vampire: The Requiem where vampires don't fall unconscious after having their health bars filled with bashing damage, and can still fight on as long as they have even a single health slot of non-lethal damage left. This is justified, however, because Vampires can control their blood flow, to prevent themselves from bleeding out, and as the undead, their wounds don't get better or worse.
In Wraith The Oblivion, a wraith's corpus (its physical form) is only a shell surrounding its psyche, so damage doesn't hinder you and pain is at most psychosomatic (you can even voluntarily sacrifice a corpus level to become temporarily intangible, which lets you walk through walls). If you lose every point, however, you are instantly in deep trouble, because the real purpose of the corpus is to anchor you to the Shadowlands, and without it your psyche is tossed into the Tempest (the "next level") where you're an open target for psychological attacks from your Shadow and its allies.
Applies to any multi-wound model in the Warhammer and Warhammer 40,000 games, as well as several of their spinoffs, even swarms that actually represent multiple creatures with its number of wounds and attacks.
Although some units have special rules that are based on the wounds remaining/taken - a Steam Tank has more chance of blowing up if you push it hard when it's already taken damage, a Doomwheel has a greater (even more than usual...) chance of going out of control the more it gets damaged, and in previous editions Hydras have had their number of attacks linked to the number of wounds (read: heads) left. Of course, it works both ways as there are items or special rules that give bonus attacks or powers as the model or unit gets closer to death.
Averted with the Doom of Malai'tai and inverted with the Clawed Fiends. The former gets proportionally stronger with each wound it has (it can gain wounds during the course of the game) as it's wound statistic is directly tied to it's strength (both it's innate strength, and the strength of it's weapon). Clawed Fiends, on the other hand, gains attacks when it loses wounds.
Played somewhat straight in Nobilis 2nd edition, where the characters are basically gods. All Nobles have one or more deadly, serious, and surface wounds they can take before death. A Noble suffers no ill effect for any lesser damage until they have used up all their wound ranks of a higher level.note Therefore, you can't beat a Noble to death with your bare hands without miraculous strength because a Noble can take an infinite number of surface or serious wounds as long as that Noble has a single deadly wound left. Gets worse when multiple gifts like Durant and Immortal increase the minimum threshold of damage needed to inflict each level of wound. Even the weakest Noble could survive three gunshots to the head without being significantly impaired. You do however have to spend slightly more miracle points on miracles when out of deadly wounds (and more when out of serious wounds).
Nobles are also nearly immune to non-miraculous damage thanks to the Rite of Holy Fire, which blocks mortal "insult" against you. The higher your Spirit, the more fine-grained the block, so while any Noble would be immune to the outrage of a mortal tactical nuclear strike, an Inferno would also be immune to a mortal's petty fists as well. At middle tiers, this means that you could walk out of a car bombing, shrug off machine gun fire, and then be taken down by a punk with a switchblade.
Third edition mixes this up a bit. You take wounds when you resist the impact of a miracle, but each wound brings with it a bond (for surface wounds) or affliction (for those higher up the tree), and taking a wound of a certain level heals all the ones below it. This means, among other things, that players with Bonds of low combat utility sometimes go out of their way to take surface wounds that provide Bonds such as "I'm mad that he ruined my suit (1)", and that nuking a Noble might in fact make them hugely resistant to physical damage when they take an Affliction of "I'm a ghost (4)". However, Afflictions activate miracles when the HG thinks they should, and are under no restriction preventing them from being massive inconveniences, so unless a player is very careful they are likely to start running into self-originating harmful miracles as long as they're wounded - the guy who took ghostliness now has to possess an Anchor to make his physical actions relevant, for example.
Subverted in The Dresden Files RPG, where the player can elect to remove damage by taking "Consequences" like Bruised Ribs or Broken Leg, which have lasting effects (possibly even persisting the rest of the character's life, depending on the severity) and can be exploited by opponents to do extra damage or otherwise hamper the character's ability to act.
Similarly subverted in other games using the FATE system, such as Spirit Of The Century. The mechanics are meant to emulate and serve storytelling conventions, so that the damage you take isn't even really damage, but "stress" against your health (or mental health, or reputation, or whatever else the game assigns them to). If you get a moment to rest, stress wipes away easily - but if it keeps piling up, then you have to start taking those Consequences or get taken out.
Also averted by many (not quite all, though the two already given are among them) iterations of the Fate system where it's entirely possible for a character to be taken out despite still having stress boxes remaining. (In these versions, each 'hit' applied to the stress track marks off only one box, but it has to be one of appropriate 'size' or, failing that, the next higher-rated one that's still free. And if there isn't one left over, that character is out even if they still have lower-rated free boxes remaining.)
Averted in Tunnels And Trolls, but only for monsters: a wounded monster fights less well than an unwounded one, but player characters consider all wounds but the last one (when the character dies) to be superficial.
Averted by Burning Wheel. There's something that looks like a wound meter, but it's only used to determine just how incapacitating each wound is. Wounds aren't cumulative, but the penalties they impose are. It's very hard to land a single blow that kills an enemy. It's easy to keep hammering on a foe until it gives up, or to beat it into unconsciousness/immobility and then cut its throat at your leisure.
Averted in most of The World of Darkness RPGs by White Wolf: the more damaged you are, the more dice you lose from your actions, to the point where sufficient injury denies you the use of your skills entirely. It even varies from supernatural to supernatural, where vampires are able to ignore more wound penalties than humans, and so on.
Promethean: The Created is the exception, playing the trope straight: Prometheans are literally held together by their own life force. In fact, they don't even suffer wound or injury penalties until they have taken so much damage that they are only a few hitpoints away from permanent death, and even then, if they get healed, there's no real lasting damage. And even if they don't get healed, they can still rise from death. And every Promethean gets one "Get Out Of Death Free" card.
Exalted averts this...in theory. The more health levels you mark off with damage, the greater the penalty on rolls. However. Due to the low number of health levels even for people who invest heavily in Charms to get more, and the insanely high amounts of damage Exalts can dish out, and the availability of cheap perfect defences, you end up with a situation in which two Exalts leap around for twenty minutes in a battle of attrition, perfectly evading or parrying each other's attacks, until one of them runs out of Essence and dies instantly, neither side having felt a wound penalty that wasn't instant death. Against most opponents without perfect defences, you skip the battle of attrition and cut straight to the instant death, still without the involvement of a wound penalty (and Extrasdie so easily almost nobody remembers they have wound penalties because you can kill them with harsh language or a finger poke).
As a shameless plug for the game, there are actual ways to kill with harsh language, literally.
Following the 2.5 errata, Exalted is now a full aversion, with no qualifiers whatsoever. With decreased lethality across the board, armour actually being useful now, and perfect spam being beaten with the nerf goremaul until it stopped twitching, those health level penalties are now actually relevant.
This new Exalted system of combat (which is known for it's brokenness, to the point where a selling point for the 3rd edition is a complete overhaul of the combat rules) leads to a thing called "The death spiral" where, a player, having taken damage, takes penalties to rolls, and thus, continues to take damage, which make the penalties to rolls even worse...
Most Exalts have a Charm that allows them to bypass wound penalties, but not all of those are actually good.
Averted in PDQ System games like Dead Inside, Truth & Justice, and Swashbucklers of the 7 Skies. Your skills and traits (called "Qualities" or "Fortes" depending on the game) are your health, with damage gradually eroding your capabilities. The defender gets to choose which Qualities suck up the damage (with or without Handwave as to why getting punched reduces your Accounting skill), letting you preserve relevant skills in a contest at the expense of irrelevant skills.
In early games, you were out once any of your skills went below the lowest possible rank, meaning you could opt to throw a fight by tanking your lowest skills quickly, or hold on at length by eroding all your skills evenly. By 7 Skies, you were down only once all your skills were out.
Starting with Truth & Justice, the first Quality you take damage to in an encounter is also supposed to be noted down by the Game Master for later use as a "story hook," meaning the damage a Player Character takes creates consequences in their life. This leads to fan jokes that Spider-Man had so many problems with his love life because he "kept getting punched in the Girlfriend" Quality.
Played strait in Magic: The Gathering, you start with twenty life, and can gain into the hundreds with the right deck. Except for a few cards that respond to life totals at other levels, the only thing they do is say that you die at zero and that you can't pay life you don't have for abilities. There are even a few deck builds based around a card that lets a player effectively pay life as mana coupled with an X-pay burn spell(which deals damage based on how much Mana you pay) to precisely kill the opponent on turn 2-3 with 1 point of life left.
Averted in the Mistborn Adventure Game. If an attack deals more than a quarter of your current Resilience in damage, you take a Serious Burden, which anyone attacking or opposing you can invoke to add a die to their pool. If the attack deals more than half your Resilience, you take a Grave Burden, which is worth two dice to your opponents.