A common trait of monsters is the Weaksauce Weakness that allows humans to face them. After all, if monsters are so powerful and scary how come that they haven't already taken over? Thus, fairies are repelled by iron, demons run away in fear before a drop of Holy water, vampires can't stand sunlight, werewolves only roam when there's a full moon, mages need to utter magic words to cast spells, and so on. Not only monsters have this problem, very often characters that are too powerful are bound to have a restriction that, if they're villains, gives the Hero a chance against them and, if they're heroes, prevents them from being too boring to watch.
It follows that a villain with a weakness that both the Heroes and audience is familiar with, will instantly become a bigger threat if said character gets it removed. Feel sorry for its enemies if their main strategy is Attack Its Weak Point.
The weakness doesn't necessarily have to be a Kryptonite Factor, it could be a well known flaw that the heroes always exploit, like a detective that can always be sure that the criminal will left clues behind or that serial killers always follow a pattern that he can deduce to find them.
A character can achieve this through focused (and generally painful) training, get this status as a side effect of increasing their powers, thanks to magical or scientific experiments, by being Badass or just gifted. To remove a Kryptonite Factor, a recurrent method is exposing to small doses of it, in a similar fashion to characters with Acquired Poison Immunity.
Just to be clear, this trope doesn't cover cases when the author changes the character into not having a weak point it used to have, it only counts when it happens in-universe. It also has nothing to do with heroic Ancient Greek amputees.
Compare with Fight Off the Kryptonite, when the character doesn't lose his weakness but tries to fight it through sheer will force, and Kryptonite-Proof Suit, where the character takes measures to avoid it. Similar to No-Sell, but instead of ignoring other characters' powers, in this case what's ignored are the natural weaknesses. Adaptive Ability is similar where one develops an immunity to a weakness after a single exposure. For instances where one never had the weakness in question to begin with, see Fake Weakness.
- A commercial for Nutrigrain breakfast bars had a family of vampires. One of the vampires stated "Ve vere not morning people" until they discovered Nutrigrain bars—and showed them sitting at the table in sunlight having them for breakfast.
- The Angels from Neon Genesis Evangelion had a Core that, if destroyed, would meant the Angel's destruction as well. But the eleventh Angel had a body made of nanoentities, meaning that it didn't have a core, at least not that the heroes could detect and destroy as usual, but it also had an Adaptive Ability that allowed it to learn and become immune to anything that they used against it.
- Saiyans from Dragon Ball Z suffer an agonizing pain when their tails are squeezed. Goku used this against Raditz and Piccolo tried to do the same against Nappa, just to learn that he and Vegeta were immune to this; they claim that only low-class Saiyan warriors are affected by this, whereas they're Saiyan Elites. Goku trained himself to remove this weakness in the past, before his tail was permanently removed.
- Jojos Bizarre Adventure :
- In Battle Tendency, a Pillar Man who wears a Stone Mask empowered with the Red Stone of Aja will become immune to both sunlight and the Ripple, the only two things that could kill them.
- A villain from Part 4, the Big Bad Kira, was the first character with a stand that could operate regardless of distance, while the normal rule is that if there's a stand, its user is nearby. However, his stand had another limitations: it couldn't be controlled at will and Kira couldn't know what was it doing or seeing. He wasn't the last one.
- In both Part 4 and 5 there was a character whose stand would activate after the user's death, and since the only surefire way to destroy a stand was killing the user, they were impossible to destroy.
- In the world of One Piece, there's an universal rule that says that, if you eat more than one Devil Fruit, you die. Blackbeard has seemingly broken the rule, though no one but him knows how he achieved it.
- Walpurgisnatch from Puella Magi Madoka Magica, the only witch that could exist outside a barrier and therefore wreak havoc on the real world.
- An episode of Pokémon featured a trainer that made her Steel-type Skarmory fight exclusively against Fire Pokémon until it overcame its weakness against Fire.
- In Phantom Quest Corp., Bosco eventually became immune to sunlight through controlled exposure to highpowered UV lamps. Which was done as part of his attempt to give up being a vampire, because he'd fallen in love with Makiko.
- Kingdom Come: It is revealed early on that because of all the yellow solar rays Superman has absorbed at that point, he gained an eventual immunity to all forms of Kryptonite, making him effectively invincible to everything but magic.
- Subverted by The Riddler in the Batman story that established that he's obsessively compelled to leave clues, otherwise he can't successfully commit a crime. The Riddler starts using forms of self-therapy to overcome his compulsion, and eventually manages to steal some jewelry without leaving any riddles. Meanwhile, Batman and Robin keep stumbling across strange people and events, which they end up connecting together to figure out Riddler's next crime. It's revealed when they catch him that Riddler hadn't overcome his compulsion—he started sleepwalking and left clues subconsciously. In another storyline (possibly the same one), Riddler subconsciously leaving clues actually led him to surrender to Batman, because he realized this meant he really was crazy.
- Becoming this is Deacon Frost's goal in Blade. Until he completes the dark ritual, he and his followers have to use a thick covering of sun lotion to survive in sunlight.
- In I, Robot , everyone except Detective Spooner is convinced that no robot would ever attack a human due to their programming. It turns out that the main suspect, Sonny, has a second positronic brain that allows him to understand the Three Laws, but disobey them at will. In a twist, Sonny doesn't murder anyone even with that restriction removed; the only person he killed asked him to do it.
- In the climax of Underworld: Evolution, Selene gains immunity to UV radiation (and thus sunlight) by drinking Alexander Corvinus' blood and becoming a vampire-Immortal hybrid. As previously shown, even the most powerful vampires suffer lethal burns when exposed to sunlight.
- Dracula in Van Helsing displays none of the weaknesses commonly associated with vampires; Anna mentions multiple weapons that have failed to destroy him in the past, he survives being staked through the heart onscreen, and uses a Cross-Melting Aura to destroy the silver crucifix Van Helsing threatens him with. Carl eventually figures out that the only thing capable of killing him is a werewolf.
- Gremlins 2: The New Batch: When the Gremlins break into the genetics lab, one of them mutates into a Bat-Gremlin hybrid. Another Gremlin who recently gained sentience because of a brain potion injects his winged compadre with another mixture that makes him resistant to the Gremlins' fatal weakness to sunlight so that he can go on a rampage in the city. Why he didn't take the potion himself is another matter.
- The Yeerks' need to leave their hosts once every three days to absorb Kandrona rays with their real bodies, otherwise they die of starvation. In their planet, the Kandrona rays are generated by their sun, on Earth they have a secret base with an artificial generator.
- A renegade Yeerk that couldn't afford to go back to the base found a way to survive anyway, by killing and eating a fellow Yeerk every three days.
- In another book the Yeerks found a substitute for Kandrona that they could absorb without leaving the host's body, unfortunately it was highly addictive, hindered their ability to control the host, and could potentially drive them mad, replacing their original weakness with something worse.
- Artemis Fowl: Demons, as a species, are no longer able to use magic after they reach their adult stage, called warping (warlocks are extremely rare, but don't warp). So when the Big Bad starts using magic despite being, in his own words, "such a magnificently warped creature"... it turns out there's an unconscious warlock's spirit inhabiting his body.
- The Terry Pratchett book Carpe Jugulum has a family of vampires whose father has trained them all to be immune to sunlight and to not react to holy symbols or garlic, as one is just a collection of lines and curves and the other is merely a member of the Allium family. This bites back hard at the end of the book, though, when the family can't stop seeing holy symbols everywhere. After all, they're just straight lines and curves...
- In The Dresden Files, the Fomor can use magic over running water due to their natural affinity for entropy magic, unlike demons, spirits, mortal practitioners, faeries, semi-mortals, and quite possibly gods. And yet, it is still possible to use magic on running water itself, but not when, say, on a boat.
- In Harry Potter and the Goblet of Fire, Voldemort uses Harry's blood in a ritual to restore him to power, which also allows him to bypass the Power of Love protection bestowed on Harry by his mother's sacrifice.
- It's worth noting that by removing this one Achilles Heel, he created a new one which bit him in the ass spectacularly, shortly before the climactic final battle: As long as Voldemort lived, the Killing Curse was ineffective on Harry. In Voldemort's defense, he couldn't see that one coming. Even Dumbledore didn't know for sure.
- Hercule Poirot once faced a killer that he couldn't gather evidence against because he didn't murder anyone, he subtly manipulated people with seemingly innocent remarks to hit their emotional buttons and push them into murdering. Poirot realized it but still was unable to bring the villain to justice, since none of his actions could be seem as a crime so he broke his moral code and killed the guy, lamenting how that, at the end, the villain even managed to make Poirot himself a murderer.
- Saruman from The Lord of the Rings created a new breed of Orcs after his Face–Heel Turn, the Uruk Hai, that weren't weakened by sunlight unlike ordinary Orcs. They were also stronger and overall superior.
- Twilight vampires feel a strong, almost uncontrollable urge for blood, the only exception being Bella after her Vampification in Breaking Dawn.
- Lestat of Anne Rice's The Vampire Chronicles series does this accidentally. After living several hundred years, he decides to commit suicide by flying into the desert sun. As vampires can't stay conscious during the day, he passes out during the attempt, and wakes up, severely weakened, submerged in sand where he fell after passing out. Although the experience nearly kills him, his body heals into the appearance of a man with a deep, permanent, suntan.
- Portions of the Star Trek: The Next Generation novel "Imzadi" by Peter David take place decades after the events of the series. At the climax, Commodore Data fights Admiral Riker, and when his opponent reaches for the off-switch between his shoulder blades:
Data: I had it removed some time ago, sir. It was becoming a nuisance.
- Given the amount of vampires in Buffy the Vampire Slayer and Angel, there's bound to be examples of vampires immune to their traditional weaknesses
- One involved removing the vampire's heart surgically (which will kill him eventually, but renders him immune to vampire weaknesses until then).
- Another example was when the Fang Gang goes to Pylea, Angel discovers that the dimension's sun doesn't harm him, allowing him to operate during the daytime.
- Dracula went to Gypsies sometime in the 1800s and traded vampire secrets for protection from a few Vampire weaknesses. Such as now he cannot be killed by a stake through the heart.
- The first Buffy and Angel crossover episodes featured a ring that made a vampire unkillable and featured a fight between Spike and Buffy in broad daylight. Needless to say, it was destroyed soon after.
- Demons in Supernatural are weak to numerous mystical effects such as salt lines, iron, devil traps, holy water, hallowed ground, and the demon killing knife. The top tier ones, however, prove to be immune to most.
- True Blood: Sookie's blood, because of her fairy ancestry, has the power to give vampires this ability. It's temporary though.
- One of the characters in Neverwinter Nights is secretly a werewolf, masquerading as a merchant and selling silver artifacts and wolfsbane herb to werewolf hunters. Not only does this keep suspicion away from him, but he also claims that exposing himself to his weaknesses in this way has allowed him to build up a tolerance to them.
- Legacy of Kain:
- Moebius has a scepter that is enchanted to weaken any vampires he uses it against. Raziel is completely unaffected by the scepter due to him being 'remade', and while Kain is initially affected by the scepter, he discovers that he's become immune to its effects when Moebius tries to use it against him towards the end of Defiance (as a side-effect of Raziel ripping Kain's heart from his chest during a previous encounter).
- And in Soul Reaver, the Rahabim Vampires have evolved into amphibians, overcoming the vampiric weakness to water (but losing the ability to resist sunlight) in the process. By killing their leader Rahab and absorbing his soul, Raziel also overcomes this weakness.
- In The Elder Scrolls V: Skyrim's Dawnguard expansion pack, the vampire Lord Harkon intends to create a permanent eclipse to black out the sun, allowing his clan to hunt freely without being hindered by their weakness to sunlight.
- According to lore in The Elder Scrolls IV: Oblivion, the Cyrodiilic strain of vampires long, long ago made a deal with Clavicus Vile (the Daedric Prince of Pacts) that allowed them to decrease or outright lose the weaknesses of vampirism so long as they kept fed (a vampire that have fed in the last day can pass as mortal, take no damage from sunlight, and is only somewhat weaker against fire — and as one quest reveals, a well-fed vampire is mortal enough to sire a child the old-fashioned way), at the cost of also downplaying the strengths of vampirism until they go without feeding. Skyrim brought in a similar mechanic for Skyrim vampires without the lore explanation, although in their case sunlight will always weaken no matter the stage — it's just increasingly crippling.
- In Xenoblade, the otherwise hard to damage Mechon are easily dispatched by the Monado. This isn't the case for the later introduced faced Mechon, who No-Sell the Monado like any other weapon, which in turn forces to take them down the hard way.
- Metroids, the recurring enemies that can suck up energy from any living thing in the Metroid franchise, will always have a weakness to cold based attacks. note In Metroid: Other M, there's an area that is housing altered Metroids that have their cold weakness removed. Adam stops Samus from going into that room and goes in there himself to blow up the sector in a Heroic Sacrifice so that Samus can take down Ridley, a foe she has more experience with compared to Adam.
- In the Wii installment of Punch-Out!!, many opponents cover up their weaknesses during Title Defense. For example, Glass Joe wears headgear to protect his glass jaw while King Hippo wears a manhole cover over his stomach. Special mention, however, goes to Bald Bull. Normally, Bald Bull will instantly be knocked down if he's punched in the stomach during his Bull Charge. In Title Defense? Bald Bull will keep his balance and go right back to fighting.
- The Adventures of Dr. McNinja. Evil ninja Frans Rayner initially has a pressure point—when struck there, he is completely paralyzed for a short while. However, Rayner also has enough mental control over his body that, any time his pressure point is discovered, he can change its location. So, no paralyzing strike ever works against Rayner twice. Eventually, Rayner completely eliminates his weak point. He suffers a mortal injury, and survives by becoming a cyborg—in the process, he has the presence of mind to shift his pressure point into one of his fleshy bits that gets cut off.
- Demona from Gargoyles gained the ability to turn into a human during day, instead of turning into stone like her brothers. While she hates humans and therefore hates her daytime form, she became more dangerous by being mobile during the daytime to do as she pleases while normal gargoyles sleep.
- In Megamind, Megamind creates a new superhero using Metroman's genes. This new "hero", Titan, has the same powers as Metroman. That's why Megamind is shocked to learn that, unlike Metroman, he's immune to copper. In this case, it hints at the fact that Metroman was never weak against copper to begin with; he merely faked it. The weakness is not so much removed as never existed in the first place.
- Mumm-Ra, the Big Bad of ThunderCats (1985), could, for all his strength and dark magic, be repelled if he could be tricked into seeing his reflection. Later on in the show he lost this weakness and was a significantly more dangerous threat because of it.
- In Young Justice, Superboy could be put into a trance by Lex Luthor with the phrase "red sun", due to him being cloned by Lex. The first time this happened to him, he woke up several hours after attempting to attack Lex. The second time he tries to attack Lex, the same thing happens; until the rest of the team shows up and it was revealed that keyphrase was removed from his mind by Miss Martian.