Made Of Air: Going the opposite direction, there doesn't seem to be something to fight... but that "something" can fight you. Either they have the power of Super Smoke or the Intangible Man completely at will so that you can't attack them, or they may exist in some form that makes direct confrontation just not possible. (A possessing spirit, for example, who jumps from body to body; or an Elemental Shapeshifter whose composing element is too malleable to be directly harmed with any sort of physical force.)
Made Of Liquid, AKA The Blob: a common variant of this, when the character is made of some sort of fluid stuff that makes him tangible, but completely impervious to damage with bludgeoning or piercing weapons.
Made of Rubber: Somewhere in between the last two, where most attacks just seem to bounce off with little to no effect to the victim.
Can Only Kill Part Of Him: Fighting a Shadow. Similar to Regeneration/Regrowth/Resurrection, but basically the whatsit that you were fighting was just its... "representation" in the same world. Killing its body in this dimensional plane is a mild setback... if at all, as it can grow that back very quickly or replaced. Technically not that different from Resurrection except for semantics. Usually applies to gods, demons, and Cosmic Horror.
The Proxy: Another example of Fighting a Shadow, but differing in that the individual in question is very much present in the world and very much capable of dying through conventional means. They usually make use of other bodies or identities in order to conceal themselves and reduce the risk of death or injury through direct contact. The proxy could take the form of a remote-control robot, a cloned flesh puppet, or a victim of mind control or possession, and is usually killable. If the proxy is encountered often enough, it can give the semblance of invulnerability.
External Repair/Spare Body Parts: Like regeneration and/or regrowth, but external, most common with machines but occasionally works for the undead or supernatural foes. Chop off an arm? Meh, if it's too damaged to reattach, no big deal: it's replaceable. Blown into tiny chunks? Allies or drones will show up and rebuild. In some cases, they can modify themselves, or even abandon their body entirely after building a new one to transfer into, or, if they're Made Of Air underneath it, choosing a new one to possess.
Multiple Bodies: The classic power of the Hive Mind. Killing one body is irrelevant; at worst, it will reduce its cognitive abilities; more often, though, the only way to kill him is to kill all of him, as even one survivor may be able to recreate a whole new army of selves.
Body Surf: Similar to Multiple Bodies but at a more individualistic level. When mortally damaged, an enemy has access to other bodies and can move its consciousness to it, with possibly reforming that body to the appearance and capabilities of its original host. Such properties could include superpowers, weapons and other invulnerability properties.
Extreme Luck: You don't need to be invincible when you never get hit.
Paul in With Strings Attached. He needs it, since he's holding a shitload of energy inside him and would explode quite thoroughly without it. He is literally Made Of Diamond; his hair, nails, and teeth are either diamond or diamond-like. Presumably his bones are diamond too. He has so far been invulnerable to most everything, including dragon fire, but he has no resistance to intangible things like wraiths, and the Hunter's BFS once cut him just enough to draw blood.
Pony POV Series has the Alicorns and Draconequi, who are Physical Gods. While they can die, it takes an unholy amount of punishment to do so and being spirits, the only way to TRULY kill one is with Entropy's power or special supernatural weapons. Otherwise just their mortal form is destroyed and they survive, only they can no longer manifest in the mortal world. They're the Made Of Diamond and Healing Factor types, as they're extremely hard to hurt and can regenerate from nearly any damage (Alicorns by regenerating, Draconequi by erasing damage). Rancor, the Draconequi of Passions, Violence, and Revenge, has the added bonus of being immune to physical violence, meaning the only way to actually hurt her is to use methods that don't qualify as violence. However, being a young Draconequus (relatively speaking) she hasn't learned to erase damage yet and has to recharge herself to heal from damage.
Then there's Santa Hooves, who is literally impossible to touch with anything by good intentions. As a result, any attack just bounces off, phases through, or is simply ignored. This includes Discord's power. How he does it is unknown, and even Discord is completely shocked and frustrated by it.
Films — Animated
The title character in the The Iron Giant combines being "Made of Diamond" (survives heavy weaponry from tanks), as well as a mixture of "Regeneration" and "External Repair" (even after being blown apart, the Iron Giant is capable of self-repair while its pieces crawl back together from various places to rebuild itself).
WALL•E's cockroach, who survives being squashed by WALL-E (twice!) and nuked by EVE. He just pops right back up after each accident. However, he's otherwise powerless beyond his survival skills; he's just there to be a cute pet.
Another Pixar film, The Incredibles, deconstructs this a bit. Mr. Incredible can be hurt, as evidenced by a small scratch he receives going up against an omnicidal robot, but that's the only injury he receives and he has super strength to go along with it. That said, he doesn't have super anchoring abilities (he gets smacked around a lot), and when he stops a train he does so by bracing himself first and visibly winces just before impact.
The Omnidroids, which can only be damaged by themselves, according to Mr. Incredible. Special mention goes to the tenth model, who proved immune to the goverments weapons.
Olaf in Frozen receives a lot of Amusing Injuries throughout the film such as being separated from body parts, but that only acts as an inconvenience since he's a snowman. The only thing that can kill him is heat, and even that won't work since Elsa creates a personal snow cloud for him in the end.
Films — Live-Action
The Addams Family. It's not really clear what nature their invulnerability is, of how it works since it's entirely played for laughs. Lurch takes a 20 pound bowling ball to the head from a dozen stories up and barely notices, so it may be they're all Made Of Diamond, but it also extends to poisons, electrocution, and anything else they can get a gag out of. When Debbie aims a gun at him (after blowing up the house with Uncle Fester inside, which he walks away from without harm) Fester thinks she's flirting with him. They apparently use cyanide as a condiment. Even electrocuting Uncle Fester just lets him power a lightbulb with his mouth. Nothing stops them.
In addition to diamond-powers, the Agents in The Matrix also manifest Body Surf and Fighting a Shadow tactics, taking over anyone still directly connected to the Matrix. Truly "killing" an Agent wasn't possible; the best one could do is kill the Agent where there are no bodies nearby for them to immediately retaliate. Neo showed enough brawn to knock unconscious three upgraded Agents at the start of The Matrix Reloaded, but these three returned to fight again later.
Neo is also effectively Made of Diamond (while inside the Matrix), specifically in The Matrix Reloaded and The Matrix Revolutions. He's able to block a sword cut with his hand, only drawing a tiny bit of blood. An on-looker lampshades this act but directs his mooks to continue to attack anyway, ignoring that Neo just proved himself to be ungodly tough even by Matrix standards. The character's NOT as invulnerable in the original movie until he learns to dis-believe the reality of the artificial world at the film's conclusion (and therefore seize the means to manipulate it). When Neo meets the multiple Smiths for the first time in Reloaded ("The Burly Brawl"), it's a case of Diamond vs. Diamond as neither can defeat the other no matter how hard they struck. Smith does draws the stalemate close to a win since there was only one Neo, who escapes from a dog-pile of nearly 100 Smiths atop him.
The Twins from The Matrix sequel, The Matrix Reloaded, combine Made of Air with Regeneration. Not only can they turn intangible at will, but while intangible they almost instantly heal any injuries they have sustained while in corporeal form. On the other hand, the Twins couldn't hurt anyone when intangible either, which the heroes used to their advantage.
Jason Voorhees from Friday the 13th progresses into it in Jason X, being given regenerative powers, explaining why he can't be killed. When he morphs into Über Jason, he becomes more Made Of Diamond than he already was. In Freddy Vs. Jason, it's outright stated that he's immortal(since not even Freddy Krueger could kill him). Jason has the partial justification of being dead to begin with (he drowned as a kid).
Freddy Krueger from A Nightmare on Elm Street is a combination of Fighting a Shadow and in some movies The Proxy. He can be pulled out of the dream world, and then either made to disappear, or with opening an old-fashioned can of whoopass. Freddy's Dead states that every time he is killed, he will be resurrected by the dream demons who gave him his powers in the first place.
This characteristic led to some fan skepticism when Freddy vs. Jason was announced. By their series' respective finales both Freddy Krueger and Jason Voorhees had morphed into for all intents and purposes immortal beings, so what's the point in a fight when neither side can win? One of them does win by the end (or technically, the humans do while the other killer is still standing), but even that was muddled by the Sequel Hook. When they do fight directly, it's pretty much Made Of Diamond versus Fighting a Shadow. When dragged into the real world Freddy is significantly weaker, although he's still pretty good competition to Jason.
Oh, you just burned Chucky, followed by decapitating him & tearing half of his limbs off? News flash, he can still kill you! Infact, even if you do manage to kill him, he can just possess another doll...
Basically, any of the daikaiju in Toho's Godzilla series — any degree of firepower short of Applied Phlebotinum (and some of that, too) or other monsters can at best annoy or distract them. Gamera (from competitor studio Daiei) is comparably tough inside his turtle shell, but more recent films have suggested his exposed limbs can be vulnerable to explosives or concentrated fire.
Godzilla himself can also regenerate from almost anything short of being completely skeletonized or reduced to a radioactive puddle — the two things that actually have killed him in the series. Presumably, this also applies to Biollante and SpaceGodzilla, however this is uncertain, as they never return to show that they actually survived the injuries sustained in their respective movies after dissolving into particles of light and fleeing to space.
In The Crow, when he comes back from the dead, Eric is completely invulnerable to being shot or hurt, until a mystic determines killing the man's crow companion leaves him vulnerable.
The Creeper in Jeepers Creepers is a regenerator with a twist: he cannibalizes his victims for parts. Literally.
From Wishmaster, trying to wish for the Djinn to go kill himself is beyond pointless. The Djinn instantly regenerates after he is ordered to blow his own head off by the heroine. "That which is eternal cannot die". The Djinn does admit it hurt immensely, so he's not absolutely invulnerable.
From the Gag Dubbed And Edited movie, Kung Pow! Enter the Fist, Master Pain, also known as Betty. His invulnerability goes so far as including having a show of power by being beaten by several men with pole weapons. This did not go over nearly so well when the 'chosen one' tries to replicate it...After Training from Hell, Chosen One is able to harm him in one on one combat, but he's still extremely hard to hurt. It turns out that the triangular caps on his chest are the source of his power, and ripping them out not only removes it but kills him.
Aereon from The Chronicles of Riddick shows off two advantages to the Made of Air version. When she's on a plane another character threatens her while she's standing by an open trap door (which would make her fall out of the plane), and goes to take a swipe at Aereon with a sword, asking if Aereon (as an Air Elemental) can fly. Aereon goes insubstantial to avoid the sword, then drift across trap door before becoming solid on the other side, where she replies: "No, we can't fly, but we do glide very well." Made all the more awesome by the fact that Aereon is being played by Judi Dench, complete with a little smirk as she says her reply.
Inspector — sorry, Chief Inspector — Jacques Clouseau would seem to be an example of the "Extremely Lucky" variant of this trope.
Clu in TRON: Legacy is the "Divine Protection" variety, in a manner. He was created by Kevin Flynn to be his assistant and stand-in while Kevin isn't in the Grid. To ensure that Clu was still there if he left, he programmed Clu to be impervious to physical harm. Unfortunately, that came back to bite Kevin in the ass... When Clu executes his Coup, Tron single-handedly dices up all the other black guards accompanying Clu, but when Tron starts attacking Clu, a cutting stroke with a data disc is merely shrugged off.
The Adventures Of Captain Marvel film serial of the 1940's is one of the earliest examples, and interestingly enough, a mild subversion. While Captain Marvel is completely immune to bullets and blades and most forms of harm, there exists technology that can hurt him enough to stun him for a while, and phenomena like molten lava is considered lethal even to him.
The titular creature in the horror parody Monster in the Closet: it emerges unscathed from an artillery bombardment, being electrocuted and shot with a prototype laser. (It turns out it can only be destroyed when all closets in the world are destroyed.)
Hancock is immune to bullets and trains. An apartment fire hurt him but even then, he survived. The only thing that can kill him is being near his wife.
The aliens in Ghosts of Mars are possessing spirits, putting them at Type 4. Moreover, while their hosts can be destroyed (qualifying them for the "nigh" part of this trope) they themselves can't, making them Invincible Villains.
Downplayed with Johann Kraus. He is virtually invulnerable whenever he assumes his intangible form, but must return to his suit within a relatively short period of time.
The nameless monster from the film No Such Thing is completely invulnerable except possibly to the invention of an arcane genius, and as he wants very much to die (he is billions of years old, or at least believes himself to be based on his memories), is seeking the hard-to-find scientist.
Spock: Scan for lifesigns. Sulu: No-one could have survived that. Spock: "He" could.
The Shrike from the Hyperion Cantos, and Rhadamanth Nemes in the Endymion half of the series, would qualify as Trope Codifiers if the series was better known. The Shrike attacks the Swiss Guard, supposedly the greatest soldiers in charted space, and kills them all without sustaining any damage. [[spoiler:Nemes is attacked by a starship that blasts her with a massive laser that only succeeds in melting the ground she'd standing on and encasing her in stone for a while. Even later, the Shrike punches her through about eight metres through solid rock. And the Shrike itself is more than just Made Of Diamond, since it possesses control over time and space even if you did manage to kill the Shrike it wouldn't accomplish anything.
In Stieg Larsson's The Girl Who Played With Fire, massive blond thug Roland Niedermann seems invulnerable to everything from full-force body blows to stab wounds and even gunfire. In fact, this is not the case: due to congenital analgesia, he simply cannot feel the damage inflicted on him. This, when paired with his enormous build, makes him appear invincible. However, the same genetic flaws that give him his strength and numbness result in him being an utterly paranoid psychopath.
In Terry Pratchett's Only You Can Save Mankind, the eponymous "mankind" is a race of aliens who are under relentless assault from a hero who Just Won't Die - the hero being a small boy playing a computer game, that of course allows you replay from the last save point whenever you die. Technically a form of The Proxy as well.
An example from Discworld: Wolfgang von Uberwald in The Fifth Elephant, being a werewolf, survives any number of horrific experiences until Vimes uses a signal flare to destroy him with fire.
Also in Discworld, vampires can be "killed" but they always come back one day. Some blood falls on their ashes or some such thing and then they are regenerated. This is one of the reasons Vimes hates them.
Zombies - after all, how do you kill somebody who is already dead? Shoot him with a crossbow, and it'll make him just annoyed. Losing a limb, or even a head is nothing that a few stitches can't fix. However, this condition doesn't (normally) give you any supernatural durability; in fact, zombies have a weakness in that they are far more vulnerable to fire due to how dry they are.
Honorary mention to Mr. Shine from Thud!!. While ordinary trolls are made out of various kinds of silicate, Mr. Shine is literally Made Of Diamond.
Even moreso, the Luggage once accidentally got stuck in Fourecks' ancient history and buried deep beneath its surface. A couple of geological eras later, an unlucky opal miner chips the opal layer covering it. Moments later it bursts out, again homing on Rincewind.
In the Incarnations of Immortality series, the Incarnations are nigh invulnerable unless they explicitly or implicitly allow it, such as when Death changes offices
The Wild Cards series had Demise, an undead and unhinged assassin whose wild card triggered during a near death experience. He ended up getting a healing factor that allowed him to return from the dead. When his head was chopped off by a similarly psychotic Ace, Dr. Tachyon analyzed the corpse and realized that his head was growing back. He ordered the body cremated, and while Demise hasn't shown up in any other books yet, well...
Wild Cards also had Golden Boy, a classic comic-book Flying Brick (without the flying) who, when hit by anything up to a 50 millimeter artillery shell, would merely glow yellow instead of getting injured. According to Dr. Tachyon, Golden Boy projected a biological forcefield around his body whenever threatened by imminent danger, whether he was aware of this danger or not.
Parodied to hell and back in Nuklear Age by Brian Clevinger. The main character Nuke gets thrown into a sun and survives, beyond him there's Atomik lad who has a nifty forcefield that blocks everything, Angus the Iron Scotsman who's covered in iron and never takes damage (apart from one nasty incident where he is found in his suit backwards), there's a guy made of tungsten, and last but not least Superion who can't be destroyed ever thanks to how his powers work.
The eromakasi (eaters of light) in Carnivores of Light and Darkness, Into Thinking Kingdoms, and the Journey of the Catechist series in general (by Alan Dean Foster) can only be killed by eromakadi, because they are basically mist, and need to be sucked in. The most powerful mage in the world has two of them as bodyguards. That isn't the only nigh invincible creature around. The wall, a several mile long wall that can walk is also next to invincible, with the main characters just running under it.
Usually when people actually run into one of H.P. Lovecraft's Great Old Ones, they end up going insane or getting brutally killed. In the few cases they manage to fight back, it turns out the beings are unkillable by mortal weapons. Sometimes they might be banished, like Nyarlatotep's avatar the Haunter in the Dark, who can't stand bright light, but even then they are likely to come back later. Others fall into the "Made of Air" category, and physical attacks go right through them. Some, like Cthulhu himself, can be harmed, but regenerate any damage within seconds.
In Call of Cthulhu a boat rams Cthulhu in the face, causing his head to blow apart, yet the only effect is to make him slightly annoyed as his head regenerates right after the boat has passed through it. (He did go back to sleep for another millennium afterwards, so it was a net win for Team Humanity.) In another story (not written by Lovecraft himself) humans try to stop the awakened Cthulhu by firing a ramjet missile carrying a 300 megaton nuclear payload right at him. It doesn't even slow him down.
Even the "normal" aliens (i.e. not the godlike extradimensional ones that destroy worlds on whim) in Lovecraft's fiction are extremely resilient, or made from some exotic matter which makes normal weapon very ineffective against them.
Not all of them. Deep Ones and Ghouls aren't especially bulletproof, and a one of the Fungi from Yuggoth was killed by dogs. And Wilbur Whateley, who got ripped apart by an attack-dog.
The One Ring itself is of the standard Made Of Diamond variety. The only thing that will destroy is to throw it back into the fires of Mount Doom where it was forged. (Or dragon fire, but the last dragon was killed in the prequel.) The entire series then revolves around accomplishing this. As Sauron's Soul Jar, it conveys similar Nigh-Invulnerability to him, and he was already quite resilient to begin with.
The Ringwraiths are incredibly difficult, though not impossible, to permanently destroy, and are immortal thanks to the powers of the nine magic rings that sustain them. The only ways to permanently destroy the Ringwraiths are to destroy their rings (which Sauron keeps in his personal possession), or destroy the One Ring. In his letters, Tolkien says that Sauron could have restored the Witch King in time, if not for those meddling hobbits dropping his Ring into a volcano.
Lord Voldemort from Harry Potter went the phylactery route to allow his spirit to remain Earthbound even after his body is destroyed. Since he can't regenerate a new body on his own, however, this turns out to be less clever than he thought.
According to Word of God, the fear inducing soul sucking Dementors are invincible. The Patronus Charm can drive them off, but they can't be destroyed by any means, magic or otherwise. Fortunately for the Harry Potter-verse, Word of God also stated that Dementors are not immortal and do eventually die.
Of course, with no soul to hang on to, they can stick around until their body crumbles (a century or so after their creation, give or take).
In R.A. Salvatore's The Cleric Quintet book 3 The Night Masks, the leader of the eponymous assassins' guild is Ghost - a scrawny, withered man who doesn't look at all imposing. He combines the Regeneration method (a Ring of Regeneration is hidden in his shoe, presumably around a toe) with the Multiple Bodies trick - he possesses an artifact, a Mirror that allows him to swap souls with someone, then kills his own fragile body with his victim's hand. When his body dies the victim's soul departs, Ghost then waits for the body to regenerate then uses the artifact to swap back, putting his soul back in his body and leaving the victim unharmed but soulless and therefore dead. The artifact in question is so powerful that it pulls Ghost's soul out of hell and back into his corpse after he is later finally killed, and has to be destroyed by the breath of an ancient red dragon... and the resulting explosion blinds the dragon in question. And if ALL THAT wasn't good enough, he has Vander, a huge giant-like humanoid called a Firbolg, as a slave with whom he will frequently forcefully swap bodies if the situation demands. Yeah.
In the Xanth series, Bink has the 'extreme luck' form of nigh invulnerability, because his talent protects him from magic attacks using coincidences and so on. The Magician Trent finally figured it out when he was trying to transform Bink and was always missing, to the point of transforming bacteria on Bink's skin instead of Bink.
This is one of the mutant abilities in Those Who Walk In Darkness by John Ridley, rendering one's skin impenetrable. The standard way of killing these mutants is to overload their pain receptors, but apparently contact poison works as well.
Jon Remillard, aka Jack the Bodiless, in Julian May's Galactic Milieu books is nigh invulnerable in his native form of a disembodied brain. His brother Marc actually remarks in the book Diamond Mask that nothing had been discovered to harm Jon in that form up to that point.
In Spider Robinson's Lady Slings the Booze several characters are protected by a bullet-proof forcefield over the entire surface of their skin, of course the flaw being that a gun fired into the mouth of one character causes the bullet to ricochet off the inside of the forcefield with results akin to a sack of chunky salsa.
Vampires in Twilight are invulnerable and sparkle as if coated in diamond dust when exposed to sunlight. The only way to kill them permanently is to rip them into shreds and burn the pieces.
Glen Cook's Black Company novels are full of this. Really high grade sorcerers are near impossible to kill due to their use of magic to do most of the things on the list. One sorceress Soulcathcher survives being beheaded. The limper survives having a building collapsed on him, shot with ballista bolts, shot with magic arrows, beheaded, burned, etc. Many sorcerers presumed dead reappear throughout the series. The only real way to make sure they're dead is to burn every sticking piece of them.
In some cases their soul and raw power (but not their personality) can still survive usually as some kind of artifact.
In Robert E. Howard's Conan the Barbarian story "Rogues in the House" Murilo argues they should leave, "Human weapons cannot harm a were-man." — and Conan's reaction is to merely tell him it's impossible and then setting out with him to escape the place.
Morgan Primus from the Star Trek: New Frontier series of books is both this and immortal. This takes its logical course when something was strong enough to destroy her body... her consciousness transferred to the ship she was on. She is currently the Andromeda-like avatar for the starship Excalibur.
Which is as close as a book can get to Actor Allusion. She looks exactly like several characters who were played by Majel Barrett onscreen, though which ones were really her and which weren't is still unclear. The Federation computer voice is also played by Majel Barrett, so it's quite fitting.
In Jericho Moon, the Biblical Joshua is endowed with Nigh Invulnerability by Yahweh's favor, remaining untouched by any of several attacks that would've killed an unprotected man. Subverted when Yahweh's own storm winds catch up an arrow and send it unerringly towards Barra, so she grabs hold of Joshua and lets the missile pass through her own body and into his. In effect, God overcomes Joshua's God-granted invulnerability.
In Warrior Cats, Lionblaze's special power is that he can't be hurt in battle. He can turn this power off if he really wants to, but it's pretty difficult; he only does it once in the series, to prove to the cat who he wants as his mate that they can control their own destinies.
Darquesse, from Skulduggery Pleasant, can heal From a Single Cell. Sometimes, she chooses not to heal, just to see what it's like to suffer injuries. The only way to kill her is to instantaneously destroy her brain, since she can heal brain damage if it's not complete. At one point, she reattaches her own head.
Evil Vulpie in A Fox Tail is made of tungsten and carbon nanotubes, making him literally Made of Diamond, bullets just annoy him, and even after he self-destructs he is repaired. In the sequel Fox Tails he shrugs off a handheld railgun with only minor damage and a bunch of mining explosives only succeed in snapping off his (still active) head. The "Goddess" gynoids he makes are similarly hard to destroy, but the Mecha-Aila takes it to extremes, surviving a bomb that was just short of a nuke and a 70-foot robotic tank, requiring an orbital bombardment to destroy her.
I Have No Mouth and I Must Scream, AM transforms the last of its human playthings into a hideous blob-like creature who can't smash his skull on a computer bank, hold his breath until he faints, or cut his throat on a rusted sheet of metal. And he wants to die so very badly, but can't even scream.
Big Bad Mayor Wilkins of Buffy the Vampire Slayer regenerated all damage, thanks to a dark ritual performed a hundred days prior to his ascension. The Next Big Bad, Adam, was Made of Diamond; until the finale none of the heroes' attacks even made him flinch. Besides which, he was sustained by a uranium power core, and so could continue functioning without a head; destroying him meant either utterly annihilating his body or destroying the power core. Adam was followed by Glory, a hell goddess who wasn't budged by anything short of semi trucks or the hammer of a troll god.
Also in the Buffyverse are the Beast, whose hide is so tough that the only thing that can hurt him is a piece of himself; The First, who's made of air; the mystic orbs that the Geek Trio use towards the end of season 6—whoever holds them is made of diamond and super strong; and Jasmine, whose weaknesses revolve around her blood.
And, in the last season of Angel, Marcus Hamilton. Until...
Hamilton: Let me say this as clearly as I can. You cannot beat me. I am a part of them. The Wolf, Ram, and Hart. Their strength flows through my veins. My blood is filled with their ancient power.
Angel (a vampire): Can you pick out the one word there you probably shouldn't have said?
Basically every Big Bad from Buffy. Dark Willow from season six was unstoppable, if it wasn't for that pesky human conscience...
Claire and Peter from Heroes — for the same reason. Both have healing powers so strong that they both regenerated after being dead for several hours, and Claire proved her resilience by being at the core of a nuclear reaction and having her skin burned off - then having it grow back leaving her perfectly unharmed just ten seconds later. Since Peter's powers are taken from Claire, he has the same potential (though, for full resurrection, she might have to be with him).
In the second season, we are introduced to Adam, who essentially has the same ability as Claire: he automatically heals all damage. He is also immortal (his body, after his ability emerged, stopped aging). It is also revealed that both Adam and Claire can use their blood to temporarily grant their powers to other people and heal them (including bringing back people from the dead). In fact his power is only thing keeping Adam alive. When he loses it he quickly withers into a pile of dust.
In season three, Sylarfinally gets his hands on Claire's power and becomes immortal as well. Peter, on the other hand, is un-immortal'd due to the sudden alteration of his power (he can only use one at a time, and therefore ages normally whenever he isn't using Claire's power - which is most of the time).
The Daleks of Doctor Who are nigh-on invulnerable, generally needing to be out-thought rather than out-fought. However, this often suits the Doctor, who is a classic Technical Pacifist.
Aim for the eyepiece! The eye* ZZZAAAPP! Even THAT apparently doesn't work anymore:
Dalek: ::sizzle:: My vision is NOT impaired!
Their Plot Armor is even stronger than their physical defenses - if even a single Dalek survives extermination, it will inevitably end up traveling back in time and regrowing the whole species. Again and again and again...
And the Doctor himself managed a regrowth in New Who: he was able to regrow a severed hand, but only because he'd only just regenerated.
Captain Jack Harkness (of Doctor Who and Torchwood) has a direct link to the Heart of the TARDIS, and just regenerates whenever he dies — which he does quite often (over 1,000 times in the twentieth century alone). Eventually Gwen Cooper, the other main character of Torchwood, stops screaming whenever Jack dies, realising that it's really no big deal. However, Jack does age very slowly.
On Battlestar Galactica the humanoid Cylons have the ability to "redownload" and resurrect in shiny new bodies after they're killed, but only when there's a resurrection ship nearby. Even if one manages to make death stick for one of them, though, there are plenty of copies. It is possible to shut an individual Cylon (or even an entire model) down for good, but the only ones with the technology to do this are the other Cylons.
As of season 4 subverted, where the Cylons have lost the ability to resurrect due to the destruction of the resurrection hub.
There are many examples of this trope in the Stargate Verse - almost every category has an example: The Ori are Gods, The Ori Priors have Divine Protection, The Kull warriors are Made of diamond, the Black Knights are Made of air, Human-form replicators are The Blob, the Wraith, the first Unas and the Replicators have Regeneration, Anubis: Can only kill part of him, Ba'al and the Replicators have Multiple bodies and Apophis had Extreme luck during the first four seasons.
Daniel Jackson, while not actually invulnerable in any reliable or definitive way, has managed to recover from death on a frightening number of occasions, arguably placing him in Resurrection. To the point where the fanon has him dying and recovering on an almost monthly basis. On one occasion, it's even lampshaded in the show late in the show's run when it's clear Daniel could not have survived the attack on the enemy. Jack utterly refuses to mourn, search for him or believe he's never coming back and instead says that he expects to see Daniel drop in naked at any moment. Sure enough, Jack's right.
The Changelings from Star Trek: Deep Space Nine are immune to any "regular" damage - they simply liquify and reshift. Odo survives being shattered (while being a glass) and run through in human form. Laas can even travel in vacuum. The only things that can kill them are beam weapons at high setting (it took over 100 hits to finish off the Martok impersonator), radiation and a special virus developed by Section 31.
Although Mirror!Odo is destroyed by a common phaser blast
Borg are hive-minded and can quickly adapt to energy weapons, although kinetic weapons can always kill them.
Also Q, though godlike aliens have weapons to kill each other - which are powerful enough to make stars go supernova as a side effect.
The Objects from The Lost Room are indestructible as long as they're outside the eponymous room. Including the Occupant.
Jesse Kilmartin of Mutant X is both the Made of Airand Made of Diamond version of this trope. His favorite tactic is to wait for someone to hit him, then punch them out while they nurse their now-broken hand. He's also used as cover, since he's not only Immune to Bullets, but he's been shown to reflect lasers and even Brennan's electrical attacks.
Ex-demon Cole Turner in Charmed became functionally invincible after absorbing the power of MANY fallen demons; he was able to use this power to return from beyond the grave so he could be with Phoebe again. Sadly, his immense power now made him a threat to her and her family, so she divorced him. To his dismay, he found that he could not even kill himself while in a stint of depression. He was eventually vanquished during a last-ditch (failed) attempt to win Phoebe back in an alternate timeline.
This - specifically the Resurrection version - was what made Big Bad Master Org so hard for the rangers to take down in Power Rangers Wild Force. While they had won a number of prior battles simply by the sheer number of Zords they had available to throw at an enemy, Master Orge was able to absorb all their attacks, regenerate without a scratch, and eventually wear down and destroy 4 different Megazords as well as the leftover stragglers. They get better.
God: Pagan gods can be killed by mere mortals, but the trope does apply to the Big G, since it seems like Death is the only entity that could kill him.
Divine protection mixed with Resurrection: In season 5 Sam and Dean are functionally incapable of staying dead. If they do die then the Angels (and in Sam's case, also Satan) will just resurrect them because they can't be used as Angelic vessels if they're dead.note After season 5, this no longer applies, though they are still protected by other forms of Plot Armor.
External Repair: Dr. Benton is a scientist who somehow gained immortality, but his body kept on decaying. In order to continue functioning he regularly harvests new organs.
Regeneration: The Leviathans recover from almost anything. The only known means of immobilizing them so far is to chop off the head, and then keeping it absolutely out of reach of the body so it can’t just reattach itself. The only thing that can kill a leviathan is the bone of a righteous person dipped in the blood of the king of hell, an alpha monster, and a fallen angel. These ingredients are nigh impossible to obtain.
Myths & Religion
Achilles. According to the Romans, his skin was impenetrable because his mother, a nymph named Thetis, dipped him in the waters of the Styx. His only weak spot was his heel, which didn't touch the water because it was where Thetis was holding him. Of course, this legend leads to a bit of Fridge Logic, even referenced in the movie Troy, as to why Achilles would bother wearing all that armor if that were the case.
Achilles is actually depicted as fighting naked in a lot of Greek art... but so are most Greek heroes.
The Nemean Lion also had impenetrable skin, according to Pindar and Bacchylides (both c. 480 BCE). The only way Hercules managed to kill it was either choking it or shooting it in the mouth with arrows (depending on the version).
Antaeus, the giant wrestler. According to Roman writer Ovid, he could not be defeated as long as he was touching the ground, as he was the son of Gaia, the Earth. Hercules quickly caught on, and finally killed him by holding him above the ground and crushing him to death in his arms.
BIONICLE featured Vezon and Fenrakk. When cursed by the Mask of Life, they gained the power to absorb any energy tossed at them and get stronger. Even throwing them in lava did not help, they just came out bigger. They were stopped by freezing time and removing the mask, but even after that, Vezon still has a knack for not dying.
The Tarrasque, a monster from Dungeons & Dragons, is not only incredibly tough but regenerates at a hideous rate and will not stay dead, and is immunized to 50% of the offensive spells. The only way to kill it is to bring it to -10 hit points (the normal point of death for living creatures in D&D) and cast wish or miracle, specifically wishing for/requesting that the Tarrasque remains dead.
The 4th edition version of the Tarrasque just plain cannot be killed; reducing it to 0 Hit Points simply banishes it back to its resting place at the core of the world. However, while still incredibly tough on account of massive hit points and all-purpose damage resistance, it no longer regenerates.
There is a Shout-Out to this creature in Starcraft, in which one of the higher-level Zerg units is called a Torrasque. It is quite durable, regenerates quickly, and is presented as being continually reincarnated by a specific cerebrate.
That may actually also be a reference to the original creature of actual legend, a dragon named "the tarrasque". It had a turtle-like shell, and proved invulnerable to everything - until blessed by a saint, at which point it became both vulnerable, and docile as a lamb. Too bad for it the local villagers weren't in a forgiving mood, despite the saint's pleading.
Another Blizzard-related Shout-Out comes from the popular Warcraft 3 map Defense of the Ancients with an item known as the Heart of Tarrasque. Providing a dramatic increase in health total and regeneration, the Hero carrying it becomes difficult to kill except by sustained vicious focus-fire from the enemy team.
Anarchy Online also has a Shout-Out to this critter by having it as one of their early endgame bosses, which drop bits of its own body that you can turn into armor.
Prior to 3rd edition, lots of D&D monsters had Nigh Invulnerability to weapons below a certain "plus" value, meaning that heroes without such equipment could only defeat them with spells, fire, or improvised alternative methods (e.g. holding a werewolf underwater until it drowns). This rule got the nickname "You Must Be This Tall To Fight This Monster", and was fortunately replaced with damage resistance in 3E.
Particularly noteworthy were the AD&D versions of the rakshasa (invulnerable to mundane weapons and nearly all magic) and the intellect devourer (same deal, and even magical weapons' damage would be reduced to almost nothing on a hit).
In the Mirrodin block of Magic: The Gathering, there is a substance called darksteel that certain objects, including some artifact creatures, are made of. Anything made of this substance is indestructible, meaning in game terms that it can't be destroyed or killed (although it can be removed through indirect means). A prime example of this is Darksteel Colossus, a huge artificial giant that not only can't be killed by usual means, but if someone manages to actually send it to the graveyard, then it is simply put back into its owner's deck to be drawn again later. The indestructibility mechanic was retained and used in later blocks, and has been applied to many things not made of darksteel.
just as an idea of how indestructible it is, Word of God says that it is easier to rewrite the laws of physics such that you find a piece of darksteel in the shape you want than it is to forge the darksteel by any conventional means.
Also in the Magic Universe is Squee, an innocent and friendly goblin who just couldn't stay dead. What started out in the books as him simply not retaining any damage as a form of comedic discontinuity was latter changed into a legitimate supernatural ability, causing him to come back from any level of abuse, even death. Unfortunately for Squee, this is used as a form of torture when Ertai, The Dragon to Big Bad Crovax, kills him over and over again.
Another MTG example is Lord Konda, the evil daimyo of Kamigawa, who stole a powerful spirit from the otherworld and bound it inside an artifact that granted him eternal life and imperviousness to harm.
Possibly the oldest example of this trope in MTG is the "Regenerate" mechanic, which (almost always for a cost, though usually a small one) negates the next attempt to kill or destroy the thing being regenerated, presumably by means of a phenomenal Healing Factor. With the right cards and a healthy stockpile of mana, your entire army can essentially become nigh-invulnerable.
Platinum Angel gives you Nigh Invulnerability, stating quite simply that while the angel is in play, you can't lose the game and your opponents can't win the game.
If you can get your life total above 30note For those who don't know, you typically start the game at 20. while he's on the field, Rune-Tail, Kisune Ascendant becomes an enchantment that makes all your creatures impervious to any and all forms of damage.
Emrakul, while not actually possessing the "Indestructible" rule, does prevent itself from being countered and being affected by almost all spells (so only colorless artifacts can harm him). Given his insanely high Power and Toughness, as well as the flying ability, this makes him VERY hard to put down.
Not only are Warhammer 40,000's Necrons Terminator-like metal skeletons with amazing damage resistance, they have the ability to teleport matter directly to their own system from their tombs for nanites to incorporate it into their forms as a self-repair mechanism powerful enough to rebuild them even if cut to pieces. And if you DO manage to get one to stay down, its various component parts will be teleported back to the tomb and rebuilt no matter what sort of damage has occurred. The Imperium doesn't even know if there exists weapons that can kill Necrons. And given the kind of weapons that exist in Warhammer 40000, that's saying quite a lot.
One Necron managed to directly regenerate from being melted into a puddle of metal. And this was not even a leader, just a Necron mook.
There is technically a way to kill Necrons and possibly their C'Tan gods — hitting them with weapons that expose them directly to the Warp, since their existence is purely material, and they can't survive the Immaterium. That's the purpose of the Blackstone Fortresses aka Talismans of Vaul. The background tends to get retconned with every version release, so this may no longer be valid.
Daemons aren't so easy to dispose of either. Powerful ones cannot actually be killed (at least with physical weapons), merely banished back into the Warp, and even doing stupendous amounts of damage only make the banishment longer. Kill a daemon, and he'll probably be back in a couple centuries, which isn't much time in Warhammer 40,000. Other supernatural entities share similar traits, such as the bodiless "walking armor" soldiers of the Thousand Sons legion of Chaos Space Marines, who have an annoying tendency to come back from the dead.
Space Marines almost constantly wear armour better than most tanks, underneath which is a three-metre-tall Super Soldier with a bullet-proof chest and multiple spare organs. Even severe damage near to the point of death doesn't stop them, as they are wired into a Dreadnought and continue fighting.
Da Orks are already ridiculously tough, being hulking brutes with physical strength equal to or greater than a fully equipped Space Marine, but they are further resilient due to being animals with a symbiotic relationship to fungi, almost completely devoid of vital organs and any injury short of missing limbs being superficial (it is thought that bolters, self-propelled explosive rounds, were invented originally to combat Orks). There are reports of Orks being decapitated, killing the person who decapitated them then reattaching their own severed head, with no problems whatsoever. Datz reel Orky.
Makari (a grot who was Ghazghkull's standard bearer) had the supernatural luck version of this, effectively granting him a great saving throw against pretty much anything. The most recent codex informs us that he "lived to the ripe old age of nine before finally being sat on by his master and subsequently fed to an ill-tempered Squiggoth."
The dwarves from the Warhammer games. While still being mortal and technically still squishy on the inside (so no "Made of" rules) the Blood Bowl rule book comments on their "Stubborn Knack of refusing to Die".
While there's not really such a thing as "invulnerability,", Prometheans come pretty damn close. For instance, most mortals and supernatural creatures take wound penalties to all actions after they take a certain amount of damage. Similarly, if their health meters fill with bashing, they have to resist passing out, and if they fill up with lethal, they start bleeding out. Prometheans experience none of this; the only way to put them down is to fill their health meters with aggravated damage. And after that, they can still come back if their Azoth is high enough. Of course, this is the World of Darkness. The only reason they're that tough (gameplay-wise) is because they need to be tough; the worldliterallyhatesthem, and the only way out is to lose their powers, including invulnerability.
Similarly, there are the slashers who follow the Mask Undertaking. Any attack against them, be it with a sword, a machine gun, or a flamethrower, only fills one box on their health meter, and it has to fill all the way before they go down (and even then, that's not much of a guarantee).
No mention of Sin-Eaters? These guys are able to Shrug off injury to a degree, cannot be knocked out, and to top it all off, unless you destroy the geist after killing them, they won't stay dead. Of course... each resurrection after the first one sends them further out of sync with the geist and may lead to a 
Mummies are effectively indestructible. They take damage pretty much the same as any other player character; the difference is they regenerate damage, and have something like 7 wound levels past incapacitated that define various levels of dismemberment to their corpse. The reason? To figure out how long it will take before they can get back up again. The answer is usually, not long.
GURPS has the Supernatural Durability advantage that gives the ability to survive any amount of punishment unfazed until you reach -5xhp and even then only one form of damage can truly kill you. The rules do say that being blown to pieces by a single attack is still lethal.
In GURPS:Supers, on the discussion of cosmic scale characters, buying enough Damage Reduction to divide an attack's damage by one billion is noted as being "alarmingly cheap" at just 1350 points. Consider that the destruction of Hiroshima required not even a hundred thousand points of damage.
Several characters in Scion come with Invulnerability, though this almost always has one caveat - a character with higher Legend can damage them. There are some exceptions to even this, however.
Liches in most games that have them will regenerate from any sort of destruction unless their Soul Jar is broken first.
In Nobilis, all Nobles know a simple rite that renders them immune to a certain level of mortal harm. Unusually, as the character gets more powerful, t mechanic, which (almost always for a cost, though usually a small one) negates the next attempt to kill or destroy the thing being regenerated, presumably by means of a phenomenal Healing Factor. With the right cards and a healthy stockpile of mana, your entire army can essentially become nigh-invulnerable.
Savage Worlds has the "Edge" (AKA feat) called 'Harder to Kill', which grants a player a 50/50 shot at survival any time they would otherwise be killed.
In accordance with The Zeroth Law of Trope Examples Marcellus in Hamlet describes the apparition of old Hamlet thus after throwing his spear fails to have any effect: "It is as the air, invulnerable."
The games uses a detailed Subsystem Damage system, where creatures usually die either from blood loss or having their brain destroyed. Unless the creature has neither blood nor brains, in which case decapitating or drowning it will work. But then maybe it doesn't need a head or need to breath either, in which case cutting in half should do the trick. Unless the creature only has one body part, making it impossible to cut in half, in which case you're screwed.
This, incidentally, is why the giant sponge is the most unusual Demonic Spider ever. It's a single body part which regenerates instantly, has no nervous system at all, and does not bleed. It can't move, but like all other limbless creatures, has a "push" attack which deals damage based on the creature's size - and since it's a giant sponge, this allows it to kill any dwarf that comes within range with a single hit. The only ways to kill it are to freeze it in ice, seal it in rock, or drag it from the water and air-drown it.
Touhou: The main protagonist, Reimu, has a Spell Card called Fantasy Heaven, which makes her completely impossible to touch. It's even implied by secondary character Kirisame Marisa that the best strategy against this ability is simply to run away. However, Reimu rarely, if ever, uses this Spell Card, and it only appears twice in the series: in Imperishable Night, where it's essentially an unlockable bonus boss (you have to dodge all her attacks within a time limit) and Scarlet Weather Rhapsody, where it's probably the most powerful Spell Card in the game. In SWR's update, Hisoutensoku, it's turned into a One-Hit K.O. move, as the damage it deals is several times a character's lifebar. However, it's rarely if ever actually used as the restrictions are rather ludicrous: Reimu has to first invoke the Spell Card, and then hit the opponent with melee-damage seven times within a time limit. While this SEEMS simple enough, Reimu's melee combat ability is only just barely adequate, and the game places high emphasis on dodging and evasion. Any reasonably able player would be able to avoid getting hit incredibly easily. It has been stated by both Marisa and Word of God that Reimu was born with this ability, and it's one that she never has to use. The implications are that being intangible is simply a natural state of being for her, and that she holds back on purpose. That's right, if she wanted to, she could defeat ANY boss ANY time without getting hit ONCE. However, that wouldn't make for a very fun game, so she's almost always in a tangible state.
Some bosses would probably be able to retaliate. For example, Yukari could adjust the border of illusion and reality to put her back on the reality side.
A long time ago, when she was still a citizen of the moon, Eirin made the Hourai Elixer, which makes the drinker absolutely immortal by effectively removing their death. Kaguya and her "rival" Mokou (and possibly Eirin herself) are the only characters known to have drank it, and as a result haved lived for almost two millenia (and counting) and are impossible to kill. When fighting the latter, a character with the explicit ability to kill anything wasn't able to kill her, and in the end she only stops fighting because of the pain (she instantly regenerates all damage, but it still hurts).
Fujiwara No Mokou: "With but a single taste, you will never become an adult. With a second taste, you will forget all disease and illness. With a third taste.... your soul will forever churn in torment!"
Many, perhaps most of the cast fits the trope (however, since the fighting they do is simply a game, many literal god characters are very easy to beat). Nearly every listed variation of this trope is in the series, including a literal made of air example in Suika, who can turn into a heavy mist.
Minor subversion: Zasalamel in Soul Calibur 3 perfected the art of reincarnation, thus allowing him to die and resurrect multiple times throughout history, retaining all of the skills and knowledge he amassed before then. The subversion is that, instead of being a boon like he thought it would be, it quickly turned into a horrible curse, as his newfound power deprived him of a peaceful death, and the literal sinking feeling that his soul was damned to hell just a little more with every death and revival, and since that revelation he sought the game's MacGuffin to try and undo his hubris.
Absolute Virtue from Final Fantasy XI is a type of Bonus Boss that has the ability to regenerate instantly, and will do so constantly. It also hits like a semi running over a tin can, will cast the most damaging spells in the entire game (often instantly and repeatedly), and possesses all the Eleventh Hour Superpowers of most job classes in the game. Oh, and it can summon baby dragons. Repeatedly. That cast devastating Area of Effect spells. And blow up. The only way the playerbase has ever beaten this mob is through a exploit, or more recently, a Zerg Rush, both of which were patched quite a while ago. And this thing has been around for years. Maybe the developers just wanted an unbeatable monster, and won't admit it. And now we have Pandemonium Warden, which at first almost took a day to defeat (they gave up), but was finally beaten by Apathy, an endgame group. The reason this is astonishing isn't simply the win, but the fact Square actually approves of the win and didn't patch Pandemonium Warden. They seem to be comfortable with only AV giving them a stiffy.
The developers finally released a video of them killing Absolute Virtue themselves, in response to no one figuring out the tricks. The trick? When the player uses their own Eleventh Hour Superpowers it blocks Absolute Virtue from using his (making it a battle of wits — the party has to block him from using powers such as Mighty Strikes (every attack is a critical hit) or Benediction (heals user to 100%)). In practice, however, this trick doesn't seem to actually work, leaving AV pretty much undefeated...
On your first playthrough of Castlevania: Dawn of Sorrow, all the bosses cannot die unless you draw a specific Magic seal. It gets difficult on the 5th Seal especially against Death and Abaddon; draw the seal wrong and you have to deal more damage before you get the opportunity to try again.
However in Julius Mode the Bosses die without you having to draw the seal. Maybe the power of the Vampire Killer has the ability to negate the Bosses' Reconstitution due to the seals?
In the standard game, Julius tells Soma he kills them before they can regenerate.
Also he gets Yoko to help who, who originally taught Soma about the seals, which would be why he was able to take down bosses that he couldn't outright kill fast enough.
Ganon from The Legend of Zelda definitely counts. He has been killed (each time more painfully and unbelievably than the last) and he still manages to come back even stronger despite being killed over 9 times! Though this is probably because of his Triforce of Power, which gives him strength in the same way Link's and Zelda's pieces give and/or represent, respectively, their courage and wisdom.
It is actually somewhat explained in The Legend of Zelda: Skyward Sword. Ganon is actually the manifestation of Demise's hatred towards the humans who brought him down (Link and Zelda), whose bloodline Demise cursed to be forever haunted by him. Thus, Ganon always comes back, as long as Link/Zelda's descendants/reincarnations/whatever live.
Chance, The Mole and Final Boss of Syphon Filter 2, wears a special advanced full body armor suit that is not only Immune to Bullets, but also apparently to even the shockwave of grenade explosions at impact, and its weight doesn't seem to slow him down, either. His Achilles' Heel? The spinning helicopter tail rotor.
In Devil May Cry 3, the Dullahans have Made Of Diamond shields that can only be penetrated by a hard-to-pull-off attack. The Döppelganger is a shadow-entity that is invincible outside of the light, and Dante's acquisition of it makes it invincible even in light, i.e. fully invincible. It probably would laugh at the idea that Good Is Dumb. Boss Vergil in his Devil Trigger state is also invincible, in addition to regenerating any damage he might have sustained in human form. Just-timed usage of Royal Guard also makes Dante invincible to any attack; Perhaps predictably, the cutscenes never show him touching it.
Dante does use it in the boss fights against him in Devil May Cry 4, though thankfully he doesn't do it all the time or the game would be Unwinnable.
In Devil May Cry 3, Dante before the first level is impaled several times. Cutscene Dante hardly needs Royal Guard.
Cutscene Dante definitely doesn't need Royal Guard. He gets impaled at least once in each game minus the second (it's usually several times each game) so it's almost a Running Gag.
In Romancing SaGa the boss Soulgutter cannot die since it has no soul, it can only be resealed. However it can still feel pain, so deal 30,000 damage to it and it will reseal itself to escape pain.
In Planescape: Torment, it is The Nameless One's defining characteristic that he can't stay dead. As a plot point, every time he dies he returns to life as an amnesiac, generating a completely new personality for himself every time. In gameplay terms, it means the game doesn't end when he dies - the player just sees TNO wake up in the closest morgue, and the game continues as before (for gameplay reasons, and Hand Waved in-game, the amnesia doesn't kick in on these deaths). Only a being of godlike power can kill the Nameless One and make it stick, though it's hinted cremation could do the trick as well. The Nameless One also doesn't age, and the total age sum of his lives is likely counted in millennia.
Archimonde has this in the final mission of Warcraft 3 where the objective is not to kill him but merely to stall his advance for half an hour. Oddly, while his armor is Made Of Diamond, he still takes 1 damage per hit and thus can theoretically be killed by massing archers (though he has an Ankh of Reincarnation and thus must be killed twice).
The Gnosis in the Xenosaga series is the 'Made of Air' variety as the only way to combat them is to hit them when they making a phase transference to fire their energy weapons, or use of the Hilbert Effect to force them into Real Space from Imaginary Space.
Also, Albedo is Cursed with Awesome in being immortal and having super regeneration powers; he cuts/tears/blasts off his own head to demonstrate. Unfortunately, the realization that other people aren't immortal causes him to go insane. The only one who can kill him is Jr., who was specifically designed to do so... his technobabble cancels out Albedo's.
Dark Samus from the Metroid Prime subseries posses extreme regenerative power, mainly since "her" (technically its genderless) body essentially consists of pure Phazon. In Metroid Prime 2, Samus fights her multiple times, and after every fight she explodes into a cloud of Phazon particles, only to reassemble herself later. According to one scan of her, only a complete atomic disruption can kill her for good. In the 100% ending it's even shown that she survided the destruction of Dark Aether, somehow reforming in space above Aether. She is finally killed in Metroid Prime 3 when she posesses a cybernetic computer connected to the planet Phaaze, which is made primarily out of Phazon. When Samus destroys this form, all Phazon in the galaxy goes critical, destroying Dark Samus, the entire planet, and ridding the galaxy of Phazon once and for all.
Many episodes of Final Fantasy feature enemies with likely powers. Though, about all of the main villains show the ability to survive incredible damage...
In Final Fantasy IV, Golbez regenerates from a mere hand all but the DS remake. A Core unit of the Giant of Bab-il regenerates unless its support unit is destroyed. Zeromus just plain can't be hurt unless one with a pure soul uses the dark crystal on him. Among fandom even Yang and Cid are considered Made of Diamond as they respectively survive the explosion of a giant cannon while standing in it and jumping down some miles, with dynamite attached to him and hitting the ground nice and fast.
In Final Fantasy V, a few late-game enemies (and one boss trio) will automatically revive from KO within a single turn (with full HP) unless/until the player is able to land a finishing blow to the whole group simultaneously.
Also, for some reason, no one could kill Exdeath until he lost control of the Void.
In Final Fantasy VI, The Guardian in Vector is impossible to defeat. All your attacks do no damage. The reels for an absolutely unavoidable instant death attack against all enemies won't line up against him. If they do, he dies, but its adventure map sprite isn't removed, so you do not pass either way. The only way to destroy it is to wait for it to load a battle program, when it starts attacking and stops being invulnerable.
There is also Chupon/Typhon in the Colosseum. He is winnable against, but chances are that he'll just Snort your only character out of battle and that counts as a loss, so usually you do not defeat him. He has no special damage resistances, still.
In Final Fantasy X both main villains, Seymour and Sin, are able to shrug off death. Seymore sticks around as some freaky ghost, increasing in power with every death. Sin just comes back in a few years due to the method of his death also being his method of Resurrection.
In Final Fantasy Tactics, the Lucavi possess people with the use of ancient gemstones. They are rumored to keep reappearing throughout Ivalice's history and wreaking havoc. They also have ridiculous amounts of strength and HP. How the hero is going to stop them for good doesn't even occur to him. The problem is apparently solved when the stones become stuck in an alternate dimension where the Lucavi leader's spirit was imprisoned.
The comic-book-genre-based MMORPG City of Heroes includes the Made Of Diamond, Made Of Air (sort of), and Regeneration variants all as power sets for melee fighter player characters, as "Invulnerability", "Super Reflexes", and "Regeneration" respectively, as well as the "Willpower" set which combines elements of all three. In addition, some powers can create a state of intangibility, in which the affected character can neither affect nor be affected by anything.
In the science fiction MMORPG EVE Online, players are known in-game as pod pilots, named for the biostatic capsules or "pods" they use to control their ships (allowing them to replace bridge crews). A side benefit of quicker reflexes is that capsuleers are virtually immortal - whenever their pods are destroyed, a clone of theirs wakes up immediately at a cloning facility. Clones have a limited memory capacity, and if a player doesn't update his clone properly, he may lose some skills. In fiction, capsuleers may also be killed outside of their pods, or if their clone malfunctions and doesn't activate (the latter is the assumed fate of deleted characters), but as far as game mechanics go, capsuleers are immortal.
Was weakened in later games by making the rate of health regeneration decrease as your got lower on HP. At one HP, it takes a few seconds to regenerate a single point of HP.
Final Fantasy Tactics Advance has Llednar Twem. For all your encounters with him except for the last, he's protected by a special law that makes any and all attacks against him useless.
If you're a Fire Emblem villain (or The Dragon to the villain) you're made of Diamond to anyone that isn't wielding the legendary weapon of this game. Those that aren't made of diamond by an ability are made of Diamond by having RIDICULOUS Stats.
A special mention goes to Dheginsea. He embodied this trope three times over:
This is a large part of the premise for Soul Reaver, the main character is a ghoul that lives in the spirit realm and can construct a body in the material realm, if that body is destroyed (even when atomized) it just sends him back into the spectral realm. If mooks in the spectral realm "kill" him, his soul drifts around before settling in the heart of the underworld, where he regains his strength and starts again. It is said explicitly several times over the series that he is completely indestructible and that even the local god is unable to do more than play mind games with him or contain him.
In the final stage of Sonic Chronicles: The Dark Brotherhood, the party splits up into two teams. Each one ends up fighting a boss with ridiculously powerful shields at one point. When Knuckles' team faces the Gizoid Centurions, you have to survive two or three turns against them and their shields before you get a cut scene of them losing; then Sonic's team seeks out some inactive Centurions and Tails studies them to understand how the shields work and is able to jam them, allowing Knux and crew to fight them for real. After that, Sonic's crew encounters Prefect Charyb underwater, where he has a humongous advantage (plus you can't use POW Moves. After three turns, you get another cut scene, and action switches to Knuckles' team. After beating Prefect Scylla, Knuckles is able to reach the drainage switch for the room the others are in, allowing Sonic to fight Charyb for real.
Paper Mario has Bowser and Tubba Blubba. Bowser uses the Star Rod to get diamond defense that prevents all damage and status effects until the defense is taken down by the Star Spirits' power. Tubba Blubba's method is a Soul Jar in the form of his heart, locked behind a door opened by a key he closely guards. Oddly enough, it might have made sense if Tubba Blubba had sent his heart to Bowser. Granted, the Boos were the ones holding Tubba Blubba's Star Spirit, but they would only have released him upon Tubba Blubba's defeat, and if Bowser and Tubba Blubba guarded each other's methods of Nigh Invulnerability, there would be nothing to stop Tubba Blubba from wiping the Boos off the map *or* deadlocking Mario's quest.
Bowser is absolutely ridiculous even without the Star Rod. Throughout his long villainous career, he's survived lava, bottomless pits, more lava (this time getting his skin boiled off andkeeping on going without it), being thrown through a star, and being smashed by an asteroid into a black hole. He always gets back up in time for the next game.
Also, the Armored Harriors from the second game. The only way to damage these hard-heads is to knock one into the other.
Clive Barker's Jericho has Hanne Lichthammer, who, it seems, cannot be harmed (or, at the very least, cannot be killed) by bullets. It only takes Church's blood magic to trap her, and even then she has to be killed in a blood ritual.
Dead Space has the Hunter, a Necromorph who can regenerate any lost body parts and is damn near impossible to kill. He is only killed when Isaac lures him into the path of the engines of a shuttle and test fires them, roasting the Hunter.
Dead Space 2 has another Hunter-esque Necromorph. It's called the Ubermorph. If any name pretty much guarantees "impossible to kill" this Necromorph has it.
The Necromorph in general: although they are relatively easy to kill by dismemberment, they can reanimate any dead tissue, including dead Necromorph, so its only a matter of time before the remains are re-infected and come back as undead giblets and body parts trying to kill you again...and again and again and again...
Metal Gear games might have one here or there, most notably Fortune (whose "luck" means bullets cannot hit her and grenades are all duds) and The Sorrow and his army of people you killed (who are all still dead, and you can't exactly shoot a ghost). Not to mention Vamp, whose already potent regeneration abilities were enhanced with nanomachines.
Also Snake, not just gameplay-wise anymore: It may be a case of incredible determination, but in the fourth game alone, despite an artificially advanced age that other character say should preventing him from moving, he is shot, stabbed, electrocuted, lit on fire, and forced to crawl though a hallway full of microwave radiation.
Prototype's Alex Mercer has a potent Regeneration ability, he can also consume people and monsters (although those must be weakened first) to regain health, he can grow shields and armor from his own body mass, and he even regenerates himself from death by a nuclear explosion.
Even without the eating people to gain health thing, instory he's pretty much indestructible. If the game were closer to it's story, there wouldn't be a healthbar because you wouldn't need it.
To count the ways he is indestructible. You can throw cards, throw broken tank parts, break armored vehicles with your bare hands, destroy entire buildings with large special moves, kill virtually everything around you in one shot, throw someone so hard they turn into red paint on the wall, take missiles to the face, take tank shells to the face, take gunfire to the face, gatling guns, grenades, various explosions, cruise missiles, thermobaric rounds, other mutants, a nuclear missile, and even can become immune to vaccines and gases DESIGNED to kill him, and walk out of it either slightly charred or smelling minty fresh, and all damage can pretty much be recovered instantly by eating any of the squishy snacks known as humans wandering in large quantities everywhere. If the sequel, Prototype 2, is to be believed, Alex can most likely also rip tanks apart instantly, and has enough mass to wipe out the entirety of New York fairly instantly, all while happily chucking helicopters everywhere and taking down mutants the size of entire buildings. Put simply, Alex is almost entirely invincible and can do virtually anything to get himself back into safety again. Of course, obviously if he COULDN'T die, there would be no need for a life bar.
The health bar mechanic is justified through incredible Fridge Brilliance: The game over text is "Alex Mercer is dead", which is completely true, but the player character isn't Alex Mercer, it's the Blacklight virus embodied. Losing all health merely leaves the virus vulnerable to being captured by the military or Greene's mutants - it doesn't die.
One of the powerful creatures in Devil Survivor for DS, the Immortal Lord of the Demons Beldr is not only incredibly strong, but also the first time protagonists meet him he's virtually immortal (duh), but also starts the first round by attacking everyone and sucking life of every creature he hit. Since it's impossible to kill him, heroes are forced to run for their lives or retreat immediately.
He is however, according to the legends, vulnerable to Devil's Fuge, a talisman made of mistletoe. It isn't even clear whether it's real mistletoe, since it's attached to a cellphone strap.
The GMan in Half-Life. The only characters who were able to stop him at all only temporarily restrained him, and even that didn't last long.
The House of the Dead 4 has Temperance, a morbidly obese, several-stories-tall zombie whose lifebar doesn't drain. You kill him by dropping a huge clock face on him.
In many rail shooters with a Take Cover mechanic, the cover/shield your character can hide behind will withstand pretty much everything the enemy can throw at it, even superweapons of mass destruction.
The Tank in both Left 4 Dead games. He has the most health out of all infected, ranging in the thousands, but on Expert, he has the same properties as steel since Tanks in Expert get 8000 health points. Shoving him does nothing and he doesn't even stumble from a Grenade Launcher shot or from explosive ammo (oddly, exploding propane tanks or oxygen tanks make him stumble). His sheer strength alone can launch survivors across the street or off a rooftop and he also has the ability to send cars flying your way. If you play on Expert, the Tank can down you in a single hit, even if you're at 100% health! A Tank will go down but you need a lot of firepower and your friends have to concentrate their fire on the Tank to bring it down quickly, otherwise you're in for a losing battle. However, most players will try to set it on fire and keep outrunning the Tank until he burns to death.
The Reapers in Mass Effect 1. They can be killed, but they are ridiculously powerful and their defenses nearly impenetrable. At the end of the first game, one Reaper is destroyed, but it takes nearly an entire fleet down with it. And it wasn't even trying to fight back.
Mass Effect 3 clarifies exactly what it takes to kill a Reaper: three of the human alliance's largest warships can outstrip the shield regeneration of a single Reaper, provided that they're all firing on it at the same time, while it takes four to have a decent chance of killing itnote Sovereign was especially powerful even by Reaper standards, which is why it took two entire fleets to kill it. To put that in context: each of those ships is firing the equivalent of three Hiroshima bombs every two seconds, and it takes four of them (or 360 Hiroshima bombs every minute) to kill one. And even then, it's a "maybe", since the Reaper can fire back, and its main gun is equivalent to 35 Hiroshima bombs. The Reaper armada vastly outnumbers said largest warship. One of the smaller, frigate-sized Reapers takes a cruiser in orbit firing on it with broadside guns repeatedly Attacking Its Weakpoint to finally go down. The Reapers are taking casualties in the war... just not very many, and not nearly enough.
In The Last Remnant, The Conqueror is a prime example of this trope. In the many times the heroes face him, they can't even touch him ( All except Emma, who manages to make him bleed, though she gets promptly killed after this). By the time you get to the end of the game and give him a thorough thrashing, he's only a little bloody, and still almost manages to end the world, and after the credits we find out that he is still alive.
Nyx from Persona 3 is a strong example. First of all, the Nyx Avatar has to be fought and defeated in 14 different forms. (Which is not sufficient to kill it) Then after doing that, the protagonist must face Nyx in a scripted battle and throw his life away to stop her. ("Stop", not "kill." All the attack does is prevent the physical manifestation of mankind's collective wish for death from reaching Nyx and unleashing her destructive power.)
Subverted in that the protagonist could kill Nyx... except that killing Death itself is kind of a bad idea.
Isaac and Garet in Golden Sun: Dark Dawn. When they join you as a Guest Star Party Member, their attack and defense are so high that everything monsters throw at them, including the first boss, is nothing more than Scratch Damage and they have abilities that will pretty much annihilate everything that looks at them funny. Isaac and Garet's stats cannot be viewed, but they DO have their HP lowered when they are hit. However, since their HP is around 500 points and every attack does around 1 to 5 points of damage to them, killing them off would take forever. This is all justified since they literally saved the world 30 years prior and still retain all the training they had done from then to after.
The Archdemon of Dragon Age: Origins uses the Multiple Bodies strategy. If its current body is killed, the Archdemon's soul can transfer itself through the Taint to the nearest Darkspawn. Since Darkspawn are soulless vessels, the Archdemon is thus reborn. The Grey Wardens are needed because they are the only ones that can get past this Nigh Invulnerability by taking the Archdemons' souls into themselves through their Taint — an act that destroys the souls of the Archdemons and the Wardens.
WARIO. In Wario Land 2 and 3, nothing can kill him. In fact, he has to get hit in order to take on hilarious different forms so he can solve puzzles in the third one.
Well, ALMOST nothing. Wario Land 2 has nothing, but if Rudy grabs you, a Game Over screen appears, and you're kicked out and have to start the fight over.
Prince Laharl from Disgaea is the son of the overlord, and it shows. His reaction to Gordon firing a raygun at maximum power in the novels? "It tickles." Etna also claimed that 5 shots from a rocket launcher, 4 missiles at point-blank distance and 3 X-ray beam cannons did absolutely nothing to him. However, he can still be injured by high-powered and magic-imbued weapons.
In the games Laharl is Made Of Diamond, easily shaking of physical abuse from Flonne and Etna, even heavy abuse after a few hours nap, without a single scratch and talking like he did not even feel pain. An example of Cutscene Power to the Max, considering that his defense stat is only average gameplay wise.
This makes it all the more confusing when Etna kills him at the start of "Etna's mode" with a single shot. The game even points it out to you. Then it's revealed that he didn't die at all. It just extended his Deep Sleep by a few more days.
In Pokémon, the ability Wonder Guard causes a Pokemon to take no damage from attacks that it is not normally weak to from its typing. Spiritomb and Sableye have no weaknesses, so if they obtain Wonder Guard they cannot be hit by ordinary attacks. (However, Sableye can only legitimately get Wonder Guard in the third generation; in later games they can only obtain the ability by cheating, since Skill Swap, used to swap Abilities between two Pokemon, deliberately cannot swap Wonder Guard.)
Spiritomb and Sableye have a Fairy-type weakness as of X and Y, meaning that they are no longer nigh invulnerable if Wonder Guard is hacked on to them.
In Black and White, the ability Sturdy causes a Pokemon to survive any attack with at least 1 HP if it is at full health. The Pokemon Shedinja has a maximum of 1 HP, therefore if it obtains Sturdy, which it can do legitimately, it cannot be KOed by ordinary attacks.
In Tales of Vesperia, Estelle has a spell that temporarily grants Made Of Diamond status. She also has an ability that, when equipped, has a chance of making all buffs, including this one, last until the end of battle. This combo (removed from the PS3 version) is a rather easy Game Breaker to put together, particularly useful in extremely long battles.
The Beast from inFAMOUS 2. To the extent that it can survive a direct hit from a nuclear missile.
The Materials are revealed to have kept the regenerative abilities of the Darkness of the Book of Darkness, able to reconstruct their physical forms out of nothing given enough time.
The Unbreakable Darkness meanwhile, is as unbreakable as her name suggests. She's both regenerative and is made of diamond. To give an idea, Amita manages to blast her at point blank range with a Desperation Attack that, according to the Wolkenritter, exceeded the TripleBreaker attack used near the end of A's to completely destroy the physical body of the Darkness of the Book of Darkness. It didn't even put a scratch on her, despite the fact that she was at around 10% of her full strength. In the end, the were only able to stop her by getting her to keep her destructive impulses in check. And even that required a lot of help from the Materials, who were revealed to have once been a part of the same whole with her.
Trogdor the Burninator in his second appearance in Peasant's Quest is invulnerable when you try to kill him. But congratulations on getting to the end!
In Team Fortress 2The Medic can do this; if he managed to heal enough without dying he can make himself and his healing target invulnerable for about ten seconds. A good medic with fast fingers can constantly move his medi-beam to make a good quarter of his team invulnerable at once. Obviously, it’s a good uber-charge that can be a game changer.
Assault on Dark Athena shows an example of The Proxy. Mercs controlling Ghost Drones are using them as remote proxies in the field, so they themselves are protected from all harm. When Riddick uses a Drone station himself death becomes a minor nuisance to the player, as every time a drone falls in battle you just immediately wire back in and the next drone in line activates.
An Asura player character in Guild Wars 2 will sometimes reference this trope almost exactly, saying "I'm nigh invincible!" whenever they get a protection buff.
You can kill the pygmies from Pocket God all you want, but as long as their Gem of Life is intact, they'll come to life...eventually.
Fallout: New Vegas gives us Joshua Graham, the Burned Man. Co-founded the Legion with Edward 'Caesar' Sallow, led troops, killed just about anything around. Then lost an important battle. Caesar had him covered in pitch, set on fire, and tossed into the Grand Canyon. He didn't get better. He still went back home. To Utah. After the End, too, so no just catching a bus.
Yes Man has the downloadable version; this is a gameplay thing, so just in case you murder the other faction leaders you can still get to endgame.
The Boss in Saints Row The Third can get this way. Note: this is not discussing the superpowers from 4. Just normal upgrades like '100% resistance to bullets'. Ever want to no-sell a machinegun?
Dragons in Dra Koi are Fantasy and aren't considered to really exist, thus they can only be harmed by other Fantasy. They always are, too.
In Avas Demon if you find a willing demon you can enter a pact with them. Anyone who has entered a pact has this, it is a side effect of their being two souls in a single body. An example of this is Ava, who managed to get right back up after being impaled through the chest on a statue after she made a pact with Wrathia.
The Werewolves in Cry Havoc survive A LOT of automatic weapons fire. Skoll shrugs off rifle, machine gun, grenade launcher, and cannon rounds all durring one charge.
Raizel from Noblesse seems just can't be damaged by any external force, period.
One issue of Girl Genius involved a circus group being attacked by a mutant/demon horse. They blast it with various steampunk guns, unleash a swarm of poisonous bugs and a super advanced mecha, they barely even scratch it. They finally manage to cut its head off only to find out it has a second mouth starting at the base of the neck. Luckily Agatha's lighting gun manages to disintegrate it.
It would appear to be part of sparkiness as well. It's never explained precisely how Othar manages to survive all of his he-should-be-dead experiences.
The necromancer Helixa in Dominic Deegan, Oracle For Hire had such control over death with her magic that any attempt to kill her caused her to resurrect where she wished. Klo Tark attempted to get around this with an attack that paralyzed her for three hours before killing her, which would ensure she was there to interrogate when he was done with the current crisis; she bit through her tongue and choked on her blood to escape. After that one, though, she ended up Deader than Dead. Miranda Deegan, her old rival, killed her with an angelic gauntlet; its magics canceled Helixa's necromancy, and Helixa was thus Killed Off for Real. And for good measure her soul was destroyed during the "War in Hell" arc.
The same War in Hell introduced Sirellith, the Demon Lady of Treachery, who could "betray death" and come back from the dead. The only way to kill her for real was to "use her treachery against her" and kill her with part of her own body; Karnak did so by snapping a horn off of her and stabbing her with it.
A more comical version of the constant regeneration type is Ran Cossack of Bob and George. He was made out of cheap Soviet parts, so he dies from even light physical contact, but the parts were so cheap a new body with a copy of his memories would just instantly be built and teleported back. He is effectively immortal as long as they don't destroy the production machine (as he puts it "You can kill me, but you can't stop me"). The only way to defend from this is to block the teleportation with a shield. He also gets a powerful but unstable weapon that always kills him, but it can be stolen from him to make an infinite number from his respawning, and also makes him a powerful explosive or "Ran-bomb".
In addition, though Ran himself dies easily, a wall of his corpses can withstand just about anything.
Amorphs in Schlock Mercenary are classic Blobs, with some impressive (if rather disturbing) regenerative abilities. Schlock himself has not only recovered from being blown up, poured down drains, sliced into pieces splattered into droplets, but in one case, immediately returned to the fight after stopping for a quick bite of minced comrade-in-arms (I told you it was disturbing - don't worry, he saved their heads for later recovery) to gain enough extra mass to beat the creatures which did it to him in the first place.
There are also the Peteys, a massive Hive Mind comprised of a mix of A.I. and organic bodies. At one point, Petey (along with the rest of the Fleetmind) ponders the fact that despite this, they aren't quite immortal - yet.
Petey has also been working on a way to grant immortality to some of his favorite organics using Nanomachines that not only repair the body from everything incuding most forms of death, but can morph their benificiary into an armored Super Soldier form when needed.
In The Order of the Stick the evil lich Xykon can regenerate from his philo... phylia... soul hidey place (phylactery) as long as it is kept intact.
The Monster in the Darkness as well. When Miko attacks him, he complains that it tickles. Later, he doesn't even notice when Belkar attacks him.
Nesuko of The Adventures of Boschen and Nesuko eventually proves to have the regenerative version of this power, taken to its logical conclusion- her severed limbs and organs try to grow back new bodies.
Satan's kittens — Made of Diamond, not showing any signs of damage after taking grenades and shotgun blasts at point blank range.
K'Z'K — When possessing Gwynn he was a regenerator, able to pull himself together even after being run through a meat grinder. After assuming his true form he is Made of Diamond; since we never see anything hurt him in this form, we can't be sure whether he retains his regeneration.
Lord Horribus — Can only be killed through decapitation or stabbing the very center of his soul with an enchanted weapon. In fact, most demons are Made of Diamond, enough so that swords clang harmlessly off their skin.
Evil Aylee — Her head and her shell are Made of Diamond, with her (retractable) neck her only vulnerable point.
Oasis and Kusari — Resurrection. They've been blown up, shot through the head, decapitated, stabbed through the chest, and confirmed dead by medical proffesionals, but they always come back, completely uninjured. How they do this is one of the series's big mysteries. They also heal extremely well while alive.
Vampires — Depends on type, and some have pretty serious Kryptonite Factors, but they seem to be able to regenerate all damage (up to and including having their brains eaten) unless it's inflicted in the one right way.
Dr. Crabtree — Her body thoroughly infused with nanites, she's probably able to survive and heal from just about anything ( except an EMP), though it sometimes takes a while for the repair nanites to start running.
Alien Christmas elves and Santa — Taken over by parasitic alien DNA and turned into hybrid monsters, the elves — and Santa doubly so — were tough enough to be Immune to Bullets and all conventional weapons short of heavy explosives. They were still vulnerable to nerf, and it didn't keep Bun-bun from beating one up until it was begging for mercy.
Gods of Mohkadun — They can survive being Impaled with Extreme Prejudice and heal themselves afterwards. There's a plot point about someone searching for a weapon that could kill one of them.
The Wom Wom Coconut in The Egregious Adventures of the Wom Wom Coconut suffers many deaths. The hit invariably turns out to have been taken by a member of the Stunt Nut Corps, a numberless horde of coconuts identical to each other and the hero. Both the coconut and the coconut's arch-rival, Space Durian, are capable of instant reincarnation. Death is shrugged off in the same panel it occurs in.
The Mows of Dan and Mab's Furry Adventures are completely invincible. They're immune to magic, can't be harmed physically, and are too stupid (IQ: 3) for psychic attacks to have any effect. Oh, and they're adorable. Mows are basically furry Servbots.
The fae also seem to be invincible. If in-comic information is trustworthy, they can only die when they choose to.
Actually her fur is fireproof by design, this is not due to rapid regeneration (though she does that as well). The regenerative powers are more of an Informed Attribute since Grace has barely been touched by anyone. On screen anyway, apparently Damien was physically abusive to her. When Grace ends up fighting Damien, it is such a Curb Stomp Battle that he barely lands a single blow. She was more of less designed to kill Damien specifically, and being fire resistant would be necessary for that.
Like his totally not based off counterpart, Captain Broadband appears to be very difficult to damage, surviving falls out of planes, hordes of attacking fans and setting off his own bomb by punching it!
The golem girls in Wapsi Square are of the made of diamond variety. They are implied to be able to survive even complete planetary destruction.
Monica has a touch as well; after accidentally teleporting into a gunrunners hideout, they made with the More Dakka, and she survived unscathed, with only Clothing Damage to show for it. One character postulated the extreme luck form of this, and another suspected she was (unwittingly) teleporting the bullets away as soon as they touched her skin.
Vriska and Clover also have the Extreme Luck variant. It's implied that Clover can't be killed even by shooting him at point blank, he's far too lucky for that to happen, after all. Vriska's power as Thief of Light is to steal people's luck—to the point that she kills a colossal enemy because he was unlucky enough to fall off a cliff. And then Vriska also has the standard God Tier powers.
Lord English is just out-and-out immortal, and it is explicitly said that killing him is going to require glitching out existence.
Jones from Gunnerkrigg Court is completely immutable. Nothing seems to be able to harm her in any way. She compares herself to stone, but admits that the analogy is imperfect, since stones can break. She can't.
One minor character in Grrl Power has his powers listed as "Invincibility. Proper, aggravating invincibility. He has shrugged off attacks that would destroy matter on the subatomic level." It's also listed that he really doesn't have other superpowers. He's strong, but that's because he doesn't have to worry about broken bones or torn muscles.
In the Whateley Universe, they have all of the above. Lancer (and plenty of the villains) is Made Of Diamond. Phase and Jinn Sinclair are Made Of Air (due to completely different powers). Aqueous is the Blob, being composed of living water. Jody Cooms is Made Of Rubber and even calls herself Plastic Girl. Carmilla and Tennyo have the regeneration thing down: Carmilla has been torn in half, and another time decapitated (she was meditating and literally didn't notice until she found the decapitated head which also hadn't died); both fall into the projected avatar/Fighting a Shadow category. The unstoppable supervillain Deathlist is of the Good Thing You Can Heal type: he's a forcefield-protected head on a robot body with the ability to teleport the head to safety in the worst case scenario; he has killed more superheroes than any other villain in history.
Among several others, there is also SCP-073, who's powers end up making you take the damage that you try to deal him, SCP-096, who barely flinches from having a hailstorm of bullets thrown at him, SCP-458, which is indestructible despite being made of cardboard, & SCP-076-2, who can be killed, but will only respawn from the rock known as SCP-076-1. That's not even a quarter of the objects in the foundation's possession that can't be killed permanently, if at all!
They also have Doctor Bright, a researcher who ended up with his soul bonded to a small, jeweled necklace. Anyone who wears the necklace for long enough has their consciousness replaced with Bright's
Tsugha is an Eldritch Abomination whose "body" is only a part of the larger creature that exists in another dimension entirely.
Slave is a remote-controlled Super Robot Proxy that's been destroyed dozens of times. Its operator keeps rebuilding him,
Swarm, a mutant who can transform into a horde of cockroaches and seems to conjure new insects out of thin air when the old ones are crushed and destroyed.
Los Hermanos has thousands of duplicate bodies and has survived his own "death" dozens of times.
Fiasco is lucky, and can cause other people to be unlucky. He avoids injury by following Mr. Myagi's advice: "Best defende, no be dere."
In Fine Structure, the Powers are all of the "made of diamond" version. It takes a diamond-tipped syringe to break Arika's skin, and even not even that will work on Jason. But both of them pale in compairison to Anne Poole, who is possibly the single most indestructible object in existence. When she gets thrown into a black hole, the Universe breaks before she does.
The AI gods of Orion's Arm are so invulnerable that one of them engineered an all out war against itself just so it didn't have to expend any energy scraping off some outdated armor.
Red vs. Blue has theMeta, who has survived the following: a missile pod missile, sustained Gatling gun fire, Tex, several point-blank shotgun rounds, a knife in both shoulders and getting stabbed in the torso with the energy sword.
In the space of 5 minutes, he took a sniper round to the chest, 9 pistol rounds to the throat, a collision at high speeds with big-rig truck and finally falling off a bridge. All it cost him was his voice.
Since he was 'killed' by latching him to a warthog and then pushing said warthog over a cliff it's not guaranteed that he's dead since it wasn't shown if they found the body or not.
Alexandria has an indestructible body, and cannot be harmed by any purely physical attack. But she still needs to breathe.
The Siberian is absolutelyinvulnerable and unstoppable, and can bestow that invincibility to anyone she touches. Though she's actually a projection, and the person creating it lacks that invulnerability. The only thing that can stop her is impacting something that Clockblocker has frozen, and that actually cancels out both of their powers.
The Endbringers are not only insanely durable- to the point of tanking gigaton level energy blasts, but can regenerate from anything that doesn't destroy them outright.
Gray Boy possesses the ability to automatically rewind his body in time, instantly negating any injury he suffers, even if it kills him. Though he is vulnerable to Foil, because everything is vulnerable to Foil.
Scion can tank just about everything that gets thrown at him, but considering that he's the source of half the aforementioned powers listed above, that makes sense.
From Madness Combat: Tricky after his Reality Compromised powerup, and his demon form and The Auditor, who is Made of... Dark Stuff, though as of Abrogation, it's averted as Hank finds that he's vulnerable to electricity attacks.
Characters who are transformed in The Cartoon Man saga become immune to all pain, just like classic cartoon characters.
Forenzik. In chronological order, Forenzik had the abandoned studio collapse on him, got hit with a car, and had his arm chopped off. And yet he somehow comes back every time. When Freddrick Gorgote dies, it's revealed why he keeps coming back: Freddrick had a bunch of followers that would act as Forenzik to make Freddrick seem like he was immortal.
Parodied in Drawn Together, by the character Captain Hero, especially in an episode in which he and Foxxy Love go through an extreme form of BDSM relationship: because Captain Hero was indestructible, Foxxy could act out her most violent desires without fear of injuring him permanently (this disregarding the fact that all of the characters in the series die on a frequent basis, only to return shortly afterwards as if nothing had happened(which also is lampshaded by Captain Hero in one episode where he points out that they never really die anyway, procedes to behead himself with a katana just to walk in from the side and tell the viewer to try it themselves).
The Transformers are a nigh-invulnerable race, generally of the "Spare Body Parts" variety. They don't generally regenerate on their own, though some can, but pretty much any damage can be repaired; the line between what can be repaired and what's fatal, however, is nebulous at best.
Generally speaking, a Transformer can survive pratically anything as long as their spark chamber (equivalent to a human's heart) and CPU (equivalent to a human's brain) are both physically intact. As you would expect, these two components are typically located within the most heavily armored parts of their bodies, making it even more hopeless for an average human to fight one, even before taking into account the difference in physical size between an average Transformer (20-30 ft. tall) and a human (~6 ft. tall). Inflicting significant damage to other body parts will certainly slow them down, though, and might even render their vehicle form(s) useless. After all, a Transformer who lost an arm can't change into car mode with the car parts that form that arm now missing.
Decepticon Super Warriors are the nigh-invulnerable members of a nigh-invulnerable race, shrugging pretty off injuries and wounds that would kill an ordinary Cybertronian. They are usually outfitted with Restraining Bolts for this very reason.
When Animated Starscream is revived by a piece of the Allspark lodged in his head, he gains the resurrection method. Anytime that he is killed, the Allspark resurrects him. Discovering this, the Autobots opt to just capture him.
Then, of course, he is Killed Off for Real when he has the Allspark fragment removed at the end of the show.
In the G1 continuity that Starscream's spark is immortal, allowing him to possess other Transformers, and apparently float through time and space since he turns up in Beast Wars too.
An ability that was copied into BW Rampage. Rampage can regenerate, but he's later killed by a spike of raw energon going through his spark. In an earlier episode, a processed energon knife cutting parts of his spark did not do the job (though Megatron says it would've killed anyone else, and he takes it as proof of Rampage's immortality) however. It's unknown whether Starscream could be similarly killed.
A trait carried over into his Animated counterpart.
Animated Megatron goes at ground zero of an explosion capable of destroying everything in a hundred-mile radius. For comparison, the Tsar Bomba, the most powerful nuclear device ever made, had a complete destruction radius of 40 miles. Megs survives (though he's pretty banged up).
Prime Megatron is also at ground zero of a space bridge explosion. He also is revived when Bumblebee gets the cure to the Cybonic Plague from his mind.
Animated Soundwave also deserves mention, being able to take Spare Body Parts an order of magnitude further than your average Cybertronian (and, indeed, he's not Cybertronian. Possibly that has something to do with it). Twice now he's been reduced to a component the size of a human hand and remained online.
This ability is somewhat balanced out by his tendency to shatter if you hit him hard enough. The downside of a body without any Cybertronian alloys in it.
Vilgax from Ben 10 is not only Made Of Diamond to the point where he lived through being attached to a nuclear warhead as it was used to blow up his ship, but he has a tank full of healing fluid in case his next ship blows up partially, giving him Regeneration while he's in there. He's the Implacable Man's Implacable Man.
Ultimate Aggregor from Ben 10: Ultimate Alien. He takes a beating from Humongousaur (one of Ben's strongest aliens) and gets right back up without a scratch, even saying that he didn't feel a thing.
On Ben's side, we have Rath. When attacked by lasers, he doesn't get singed (there's a ring of smoke surrounding him instead). And if he drops from the sky at least a thousand of feet in the air, the most you'll get is him standing up and threatening to kick the Rath-shaped hole he made from impact.
In Disney's Gargoyles, Demona and MacBeth are essentially immortal. Due to a pact they made back in Medieval Europe, when one dies they both die. However, due to some weird twist of logic with the pact (or just the "Weird Sisters" reviving one of them), since one of them wasn't killed directly they both come back to life shortly afterward (Elisa Maza once temporarily killed Demona to keep her from fighting MacBeth so she could talk to him). Allegedly, the only way for them to permanently die is to kill each other.
In the straight-to-DVD film "The Beast With a Billion Backs," the title beast is from another universe and made of "electromatter," which the professor describes as "normal matter's bad-ass grandma." Nothing can hurt it except something else made of electromatter.
One episode showed it was commonplace for robots to periodically upload a copy of their memory which will be uploaded into a new body if they are destroyed, with Bender being the exception because of a design flaw.
Completely contradicting the previous episode where Bender championed the cause of broken-robots, which, although still fully sentient and aware, were generally just melted down for recycling materials (for beer cans and paper-weights and the like).
And contradicted by a later episode in which Bender's body is destroyed and he reflexively uploads a backup into The Cloud to become a "robot ghost"— which may also qualify as an example.
In "Jurassic Bark", Bender jumps into a pool of molten fucking lava in order to save Fry's fossilized dog. His sole injury is a slightly expanded torso chassis.
Leela is a very possible contender. In addition to being a genetically modified sewer mutant that has never lost a single fight during the series' run, she also survived a near-universally fatal space bee sting, suffering a mere two-week coma instead.
Most characters from Looney Tunes and Tom and Jerry can survive vicious beatings, gunshot wounds, falling from cliffs, and explosions unless the creators want the character to die
Subverted in Who Framed Roger Rabbit? with Dip, a mixture of various solvents that broke down the ink that Toons are drawn from in what is essentially permanent death for them.
Professor Impossible from The Venture Bros. is seemingly unkillable due to his body having the properties of elastic. He once swallowed an explosion meant to destroy an entire island in a failed attempt at suicide.
In Invader Zim, it's specifically stated that their consciousness, personality, emotions and memory are all stored in their PAKs. In a fully scripted but never animated episode, Zim could take over Dib this way; his physical body would be dead, but his mind would be in a new body, so that's okay. This theoretically applies for every single member of the Irken race, which would make them all immortals who change bodies every so often (as it's unlikely their best soldiers would be allowed to die when they're still usable). Since a PAK can attach to someone even after you killed the body hosting it and is made of the same Irken metals that allowed The Massive to go through a star without being heavily damaged, the only way to kill an Irken is to either take the PAK to Irk and have it be erased by the Control Brains or hide it away from all living life. Basically, if Zim wasn't such an idiot, he'd be nigh unstoppable.
In the same script, though, Zim claims that Dib's "filthy human body chemistry isn't compatible with the PAK. It would've destroyed you!" Of course, considering the source, that may not be the case...
Darkwing Duck has two of these characters. The Liquidator is a villain made out of water. And Dr. Bushroot, a mutant plant/duck that has can regenerate after being run over by a runing lawn mower.
Roger from American Dad!. He's seemingly immortal, and invincible. Of course, he's an alien, and not only that, he was an alien who was literally used as a crash test dummy, so it's no surprise he's practically unkillable.
Apparently even his superiors weren't aware of how invulnerable he was, as they fully expected him to have died from blunt trauma. Oh and he's fire retardant too (which he hilariously did not know).
In the early seasons of South Park, Kenny was always killed off Once an Episode, only to inexplicably return the next week. In later seasons, it's revealed that he will always resurrect due to a Lovecraftian curse that was placed on him. Worse yet, because of the curse no one can remember any of his previous demises.
The titular character from The Tick. The [Trope Name] is even invoked frequently when referencing him.
The Kane Safe-T Suits in Motorcity, though they do have a threshold before shutting off.
Sponge Bob Squarepants might seem like an average kitchen sponge with limbs & a face, but he is much more durable then that. Cut his arms off? He'll regrow them. Tear him in half? Those halfs will rejoin with eachother. Remove his internal organs? He can regrow them too. Even today, he's suffered very few injuries that left him in the hospital. Punch him with all your might? You'll collapse from exhaustion before managing to injure him in the slightest.
Water Bears. Can survive extreme heat and near Absolute Zero temperatures. Can survive being exposed to lethal doses of environmental toxins and radiation. Can survive six times the pressure of the deepest part of the ocean. Can survive without water for a decade. Can survive the vacuum of space.
Zeppelins during early World War One fell under the "made of air" category, much to the dismay of the British defenders, who tried almost everything to shoot them down, to no avail. They tried More Dakka. Passed right through, didn't even slow them down. They tried rockets and artillery. They couldn't explode on impact with fabric. They even tried using an exploding Flechette Storm. By 1916, not a single one had been shot down. But then, they finally turned the tables with incendiary ammunition, which could ignite the Zeppelins'hydrogen.
Michael Malloy, a target of gangster/bootlegger duo Tony Marino and Joe Murphy in the early 1930s. He survived being given enough alcohol to be fatal, being given whisky spiked with antifreeze, being given several drinks spiked with antifreeze, turpentine, horse liniment, and rat poisoning, being fed a sandwich made with spoiled sardines, metal shavings, and tacks, being fed a sandwich made with oysters soaked in wood alcohol (which could cause blindness, and that didn't work either), being buried in snow in below-zero temperatures, and being hit by a taxi. They finally managed to kill him by knocking him out and gassing him, but it's still unknown how he survived all the attempts on his life.
Alan Magee, who survived 28 shrapnel wounds, severe oxygen deprivation and a 22,000 foot freefall in one sitting. He lived to the ripe old age of 84.
Incidentally, York himself believed that God protected and guided him during the battle...if he was right, this may be more of a literal example than it appears.
He does have a pretty good case for that doesn't he?
While indeed U.S. Marines have a reputation for being so mean they make medicine sick, Alvin York was in fact a member of the U.S. Army's 82d Infantry Division. (The Devil Dogs still have Chesty Puller.)
The American M1 Abrams main battle tank is a nigh unstoppable war machine. Many reports from tankers and troops alike will attest to seeing the tank survive very nasty scraps and being outnumbered at least 4 to 1 and it still functioning. One report claimed that during a battle a tank was hit with nearly a dozen RPG's and shrugged off everyone of them. Another with the afforementioned 4 to 1 tanks saw one Abrams squared off against 4 T-72's, all it needed was new tracks and it was put back into circulation. Even the having it's ammo cook off inside it doesn't take it out for good.