->''"But Iron -- [[TropeNamers Cold Iron]] -- is master of them all."''
-->--'''RudyardKipling''', "Cold Iron"

One of the most mundane DepletedPhlebotinumShells and the [[AchillesHeel traditional bane]] of TheFairFolk.

Iron may be treated as naturally magic-disrupting or just poisonous for certain creatures. Sometimes it's supposed to suck the magic out of TheFairFolk (similar to the way it sucks heat out of the body), usually accompanied with screams about how "it burns". More recent fictions sometimes say that it's got something to do with ferromagnetism, or related to iron's nuclear stability.

There's no agreement about what ''"cold"'' actually means in this context. Sometimes it just mean that the iron, at the moment, isn't hot. Sometimes it's cold-worked iron. Or something more complicated, like iron that has never been smelted. Or this may be a poetic reference to any iron, just because metals that aren't hot feel cold thanks to heat conductivity. Which may be pulled as "magic vs. technology" symbolism. It may also be a reference to the fact that [[http://scitoys.com/scitoys/scitoys/magnets/magnets.html heating magnets to a certain point causes them to lose their magnetism]], so "cold" iron is iron that still has its magnetic (magic) power.

ThunderboltIron may or may not be related: meteorite alloys are iron-based and frequently cold-worked because they cannot be tempered like steel anyway. Ironically, they are good in really cold climates, not only because the fuel for a smithy would be a bigger problem, but because they don't become brittle when carbon steels do.

Cold Iron may be a reason why ArmorAndMagicDontMix, as well as a form of {{Unobtainium}} in some cases. Subtrope of FantasyMetals.

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[[foldercontrol]]

[[folder: Card Games ]]
* In ''{{Munchkin}} Bites'', Cold Iron is a trap card that only affects Changeling characters.
[[/folder]]

[[folder: Comic Books ]]
* In ''ComicBook/TheSandman'' story ''Cluracan's Tale'', the title character (a faerie) is captured and bound with cold iron chains, in a cell with cold iron bars. He has to call on the Sandman to free himself.
* In Creator/MarvelComics' ''ComicBook/TheMightyThor'', the [[TheFairFolk dark elves]] of Svartalfheim are vulnerable to iron. This is explained by iron being "the metal of humans", so it kinda fits with the nature-vs-science thing mentioned above.
** [[LampshadeHanging Lampshaded in]] ComicBook/TheIncredibleHercules #132 where the title character asks Balder (actually Malekith disguised) why the Asgardians have so much trouble with the Dark Elves, citing that even their strongest spells can be nullified by the [[WeaksauceWeakness slightest touch of iron]] and the Asgardians use steel in their ''weapons'' and ''armor''. [[JustifiedTrope Balder explains]] that the Dark Elves have powerful allies that don't share their weakness to iron (cue, a large troll that Hercules just knocked into the ground retaliates and [[NoHoldsBarredBeatdown beats the crap out of him]]).
** Marvel demons are also often vulnerable to iron. Even Adversary, an EldritchAbomination aiming to destroy creation and create a new world had to avoid contact with Colossus.
** ComicBook/IronMan is not literally iron, but just calling himself "Iron Man" is apparently reason enough for Malekith to call down TheWildHunt on him. [[spoiler:When Tony decides he's had enough, he has his ally send him a custom suit made entirely of iron complete with huge wrist-blades and a harpoon gun.]]
* In the ''ComicBook/TopTen'' spin-off ''ComicBook/{{Smax}}'', GadgeteerGenius Toybox finds herself having to defeat a dragon in a magical realm where her gadgets don't work. Her eventual solution has a big technobabble justification[[note]]Namely, [[http://en.wikipedia.org/wiki/Supernova_nucleosynthesis supernova nucleosynthesis]][[/note]], but for the setting it's essentially Cold Iron.
* In the ''ComicBook/{{Hellboy}}'' story ''The Corpse'', Hellboy exposes a changeling by touching an iron horseshoe to its forehead. Later he tests the real baby the same way, just to make sure. Conversely, in ''The Iron Shoes'' (usually published alongside ''The Corpse'', since the latter is not quite long enough to fill up an issue), some folklorists explain that a few fairy creatures don't mind iron and in fact are rather fond of it, including the title character:
-->''Live or die,\\
Win or lose,\\
Best beware...\\
MY IRON SHOES!"
* In the {{Elseworld}}s story ''Superboy's Legion'', Ferro Lad of the ComicBook/{{Legion of Super-Heroes}} is able to destroy the magical constructs of the Emerald Enchantress's magic eye -- the second he heard he was up against magic he turned into his iron form and got to business. This doesn't typically apply to other incarnations of Ferro Lad, though.
[[/folder]]

[[folder: Film ]]
* The possessed in the ''Film/NightOfTheDemons'' remake are vulnerable to rusted iron.
* An iron stake (really a railroad spike, as there's NoKillLikeOverkill) is shoved into the chest of the antagonist in the 1930s German classic ''Vampyr''.
* In ''Film/CaptainKronosVampireHunter'', the vampires' [[OurVampiresAreDifferent vulnerability]] is to iron crucifixes (or to a cruciform sword forged from an iron crucifix).
[[/folder]]

[[folder: Folklore ]]
* Putting a horseshoe over the doorway was considered a way to protect the home from intrusion of TheFairFolk- this has allusions to the story of the Exodus and the Passover. Sometimes burying a doornail was used this way too. Although often burying iron was a way to conceal the iron from TheFairFolk, and if you could get them to stand over it they would be trapped and bound until they agreed to your demands.
* There is an Italian wedding tradition that requires the groom to have iron in his back pocket.
[[/folder]]

[[folder: Literature ]]
* Creator/AndreNorton's novel ''Steel Magic''. Cold iron is defined as being any metal "forged by a mortal in the world of mortals", so the three protagonists end up using their stainless steel picnic cutlery as weapons; respectively a spoon, fork and knife. Fortunately the cutlery develops unusual properties in the magical world (such as changing size) and is pretty dramatically lethal to any magical being it touches.
* In ''Discworld/LordsAndLadies'', elves' primary sense is based on detecting magnetic fields, which iron messes with. ''Magnetised'' iron is even worse, possibly explaining the reputation of ThunderboltIron.
** The horseshoe above the door is explained by saying the shape isn't important, it's simply that horsehoes are the closest available source of iron.
** In ''Discworld/TheWeeFreeMen'', Tiffany Aching uses a {{frying pan|OfDoom}} to fight the fairies- this shows that she intuitively knew that iron would be dangerous against them.
* The ''Literature/{{Midnighters}}'' series plays with this trope. Any kind of alloyed metal (like steel) hurts darklings, cutting through them like a knife through warm butter. Rex notes that the darklings' real weakness is new ideas (hence the signifigance of names and math when fighting darklings), which means that simple worked metal worked against darklings centuries ago, worked stone arrowheads and spearheads worked against them millennia ago, and he predicts that in the future they will have to use plastics, carbon fiber, or other exotic alloys against them.
* Creator/PoulAnderson's ''Literature/OperationChaos'' series says the iron is anti-magical, but it's set in an alternate history where one of the famous physicists of the early 20th century found a way of suppressing the effect, allowing mankind to have its cake and eat it too.
* In ''Literature/ThePrincessOnTheGlassHill'', Boots controlled the {{Cool Horse}}s by throwing steel over them.
* Cold iron is any iron in the ''Literature/OctoberDaye'' series. Changelings have a better resistance to it because of their human blood, and the Coblynau, who are the only Fae able to work with iron, are a very ugly race, implied to be due to their affinity with iron.
* In Creator/TimPowers's ''Literature/OnStrangerTides'', it's said that the presence of iron disrupts magic, and the increasing use of iron-based technologies is why you don't get magic much any more.
* In ''Literature/TheDresdenFiles'', "cold iron" is ''any'' iron, even if it's been smelted into steel. Fae creatures generally have zero tolerance for it in any form -- injured by mere contact with anything containing Iron. When cut with it, the Iron sets the Faerie blood on fire. It was noted by one Fae that even if the damage is not fatal, it will leave pain that lingers for a long time. Also, bringing iron into [[SpiritWorld Faerie Territory]] (to say nothing of leaving it there) is roughly equivalent to carrying around uncontained nuclear waste. Other beings from the Nevernever don't seem to be harmed by iron - except for Fomor, who are distant relatives of the Fae. "Cold Iron" is explained as being descriptive text, kind of like "hot lead".
** There is one exception to the Faerie rule - the Mothers are, quite simply, the most powerful Fae in existence, so iron turns to rust when they touch it.
** Now that Harry is the Winter Knight - the Knights are mortal champions of the Faerie Queens - he must stay away from iron too. While not as poisonous to him as to a fae, it is an ''instant, total'' offswitch to his Knight powers. That's a very bad thing in battle, or if the extra power is keeping injuries from affecting him.
* In Fletcher Pratt and Creator/LSpragueDeCamp's novella "The Castle of Iron" HaroldShea attempts to use some gold coins conjured out of sand to pay a [[TheBlacksmith blacksmith]]; however, when he rings the coins onto the anvil, they turn back into sand. (He remembers afterward that the Creator/RudyardKipling poem that he based his incantation on had made iron "the master of them all.")
* ''Literature/TheWheelOfTime'' has "Iron to bind" to deal with the [[TheFairFolk Finn]]. It has to be true iron, though; steel doesn't work. They're also vulnerable to [[MusicSoothesTheSavageBeast music]] and [[KillItWithFire fire]].
* In ''[=The SERRAted Edge=]'' by Creator/MercedesLackey, the Elves get around the cold iron by making their cars out of fiberglass - which has the added benefit of making them lighter and therefore faster.
** In addition to harming Elves by simple contact, iron warps Elven magic. The good-guy Elves have learned to predict what running past an iron bar will do to a spell's trajectory, and take advantage of this during at least one fight scene.
* In the book ''Merlin's Godson'' the title character has to save a tiny Fae civilization from an iron nail that has accidentally fallen into their realm.
* In ''Literature/TheOnceAndFutureKing'' the young boys Wart and Kay take iron with them as protection when they visit the fairies' castle.
* In ''Literature/{{Stardust}}'' Dunstan touches some coins to an iron nail to make sure that they are real and not "fairy gold".
* In ''Literature/TheLastUnicorn'' Mommy Fortuna uses cold iron bars to trap the unicorn and the harpy. The unicorn is able to endure being closed in by the iron cage, but feels pain if she touches the bars.
* In ''Literature/TheSpiderwickChronicles'' there is a passing reference to this.
-->"Steel. It cuts ''and'' burns."
* ''Literature/TheSagaOfRecluce'' features this with regards to Chaos-mages. Iron, both naturally and when transformed into black iron by Order-mages, is a natural repository of Order. Chaos-mages who have a surplus of Chaos in their body will suffer painful burns when the two energies interact. Consequently, Chaos-mages are fond of white bronze.
** One of the more notable examples was when the Chaos-mage ruling Fairhaven had a fellow mage locked away. Her hands were bound with iron manacles, leaving her screaming in agony; the ruler idly noted that with the amount of Chaos in her body she'd likely be dead before the day was done.
* In ''Literature/DocSidhe'', the people of the fair world find the touch of iron painful (which makes things interesting for construction workers building 1930s-style steel-framed skyscrapers). Doc and his colleagues are surprised to learn that the human protagonist carries a pocketknife with a steel blade, and more surprised when he demonstrates that he can touch the blade with no ill effect.
* Creator/RudyardKipling's "Cold Iron", quoted at the page top, uses the reference solely as a metaphor for armed combat (as opposed to gold, silver, and copper, for trade, jewelry and metalcraft). Then it gets overtly Christian.
* One conversation in ''[[Literature/SpecialCircumstances Princess of Wands]]'' suggests that FBI members who ''aren't'' part of the Special Circumstances group could also take part in slaying supernatural beasties, with cold iron bayonets fitted to their rifles specifically mentioned.
* In the ''Literature/DragonKeeperTrilogy'', Dragons are hurt by the mere presence of Iron and Dragon Keepers have to use bronze or copper tools around them. This sometimes leads to problems, as in ancient China, Bronze was more expensive than Iron.
* In ''Literature/TheBartimaeusTrilogy'' all spirits are harmed by iron, but are harmed even more by silver.
* In Kate Elliott's ''[[Literature/TheSpiritwalkerTrilogy Cold Magic]]'' trilogy, cold steel in the hand of a cold mage can kill just by drawing blood.
* In ''Literature/ThePhantomOfTheOpera'' (the novel, at least), everyone at the Paris Opera relies on iron for protection against "the ghost." La Sorelli places a horseshoe on a table near an entrance for everyone to touch before entering the building, and Gabriel the chorus master runs to touch an iron doorknob when he sees the ghost walking behind the Persian, whose creepy presence often makes people touch their metal keys for protection.
* Count Dracula is slain in [[Literature/{{Dracula}} the original novel]] by a knife through the heart, drawing on the use of sharp iron and/or steel tools like knives and needles as protection against vampires.
* In ''Literature/TheSoldierSon'' iron is disruptive to magic and very harmful to magic users. The invention of the gun, which can rapidly spray iron bullets, has been instrumental in subduing the magic-using Plains People by the Gernians.
* In Josepha Sherman's ''AStrangeAndAncientName'', faeries are so harmed by iron that even the slightest scratch is a death sentence, usually fast. Being not fully of faerie means [[spoiler:being able to survive even an iron arrow wound]] - a revelation so surprising that [[spoiler:the faerie court, believing their prince to be beyond all help, almost lets him die of ''fever''.]]
* The WardStone Chronicles has witches and other dark creatures being susceptible to iron, silver, salt and some types of wood (such as oak) and as such spooks use these in their weapons (usually making oak staffs with iron or silver spikes and making pits with Iron bars lined with salt or silver chains to bind their foes)
* In Creator/RuthFrancesLong's ''Literature/TheTreacheryOfBeautifulThings'', iron is dangerous to TheFairFolk. Jack must get an iron sword to fight the nix. Then Wayland also gives him an iron jack -- toy though it is, the iron makes it dangerous.
* In ''Literature/TheSagaOfHervorAndHeidrek'', King Svafrlami catches two dwarfs by "drawing his graven sword over them", which takes away their power to vanish into the stone.
* In Creator/JulieKagawa's ''Literature/TheIronKing'', all the fairies. Meghan's ability to handle it is significant. And then there's the iron king.
* In Creator/SusanDexter's ''The Wind-Witch'', the protagonist bargains with a captured raider that she'll set him loose if he works her farm for {{a year and a day}}. Seeing no other option, he accepts the deal--even though he's a shapeshifter and using iron farm tools makes him sick. She doesn't find out there's a problem until he collapses.
** In ''The True Knight'', Wren and Galvin can't work magic on iron, and Valadan can be trapped by an iron bit.
* Elves in the ''Literature/WarlockOfGramarye'' series are vulnerable to this; it doesn't bother their half-human king, however, and occasionally they'll call him in to get rid of the stuff for them.
* In the ''HeraldsOfValdemar'' book ''Redoubt'', demons are vulnerable to a combination of Sun and Iron, in the form of an iron chain wielded in the glow produced by a [[IntellectualAnimal Suncat]]. The demons are summoned after dark by the CorruptChurch of Karse, which ironically "worships" the sun god Vkandis.
* In ''Literature/TheSecretsOfTheImmortalNicholasFlamel'' the Elder Race are weakened by iron, as it negates any and all magic. For this reason, anyone with iron in a shadowrealm will usually keep their iron tucked away somewhere so they don't offend an elder.
* Like in ''Literature/TheBartimaeusTrilogy'', iron is a common and good deterrent against ghosts in ''Literature/LockwoodAndCo''.
[[/folder]]

[[folder: Live Action TV ]]
* In the ''Series/DoctorWho'' serial ''The Daemons'', the Doctor successfully uses a trowel to fend off a gargoyle that merely ''thinks'' it's susceptible to Cold Iron.
* In ''Series/{{Supernatural}}'' iron can be used to temporarily decorporealize a ghost, along with [[http://www.supernaturalwiki.com/index.php?title=Iron other uses.]]
[[/folder]]

[[folder: Radio ]]
* Used against the "marsh weans" (a [[EnergyBeings disembodied intelligence]] believed to be evil spirits in 1950s Orkney) in the AudioPlay/BigFinishDoctorWho audio drama ''The Revenants''. The {{Technobabble}} explanation is that ferrous metal "presumably disrupt[s] the electromagnetic force that keeps it together". (In a DoingInTheWizard twofer, the local streams are heavy with iron ore, which is why they can't cross running water.)
[[/folder]]

[[folder: Tabletop RPG ]]
* ''TabletopGame/DungeonsAndDragons''
** 'Fool's Gold' spell made copper coins look like gold, but it fails when false gold touches iron.
** Depending on the edition, demons that could normally only be harmed by magical weapons could also be harmed by iron weapons.
** 3e+ has Cold Iron as a special material (like mithril or adamantine) for metal weapons. The rule of thumb is that you need this to harm (or at least, do full harm) to Fey or chaotic outsiders. The downside? It's one of the flimsier special metals (although just as strong as steel), and there's a static price that must be payed in order to enchant it, doubling the price of the the lowliest weapon enhancement (at least in 3e based systems). Still, it's arguably one of the best special materials for weapons. Fluff-wise, the ''Dungeon Master's Guide'' for 3E explains it as a special form of iron that is mined deep underground and cold-worked to preserve its properties.
** Even as early as 2nd Edition, some undead took double damage from cold iron weapons.
* In ''TabletopGame/ChangelingTheLost'', "cold iron" is anything that has a 95% iron content, and it negates any defense wrought by fae magic. The main book emphasizes that in the modern era, you'll rarely get anything like that unless it's a specialty work or from an earlier era.[[note]]Stainless steel, which makes up a lot of modern consumer goods, generally contains at least 10-15% chromium[[/note]] On top of that, you've got hand-forged iron, which is iron that's never been heated by human hands or means. This means most hand-forged iron weapons are rough and blocky, but they do hideous amounts of damage to [[TheFairFolk the True Fae]]. There are [[UnreliableNarrator many given accounts]] on why this is, but the most common one is that the Gentry once had a [[FunctionalMagic Contract]] with Iron; they got power for it in return for making sure it remained unshaped. Then humans discovered smelting, the Contract broke, and Iron is pissed.
** Likewise, in the predecessor game ''ChangelingTheDreaming'', cold iron wounds do aggravated damage to changelings - and if they're killed with it, their fae soul will never reincarnate, effectively becoming a ghost. The only reason steel doesn't screw up the Kithain is because a changeling pulled a HeroicSacrifice back in the day to ensure that it wouldn't.
* In ''TabletopGame/{{Exalted}}'' iron weapons likewise deal enhanced damage to TheFairFolk and dispels their {{glamour}}s. Name "cold iron" in this case references just the burning cold it feels to them, not any specific way of making it - any iron will do (note that most cultures use bronze or steel). Although protagonists rarely bother with such measures and generally just stab them with the same [[{{BFS}} gigantic swords of magical gold]] they use on everything else.
* The 4th Edition version of ''TabletopGame/{{GURPS}} Fantasy'' discusses cold iron, and multiple different ways of implementing it. The default is that it's simply a descriptive term for regular iron.
* ''Faery's Tale'' allows you to implement cold iron, though it's optional. Under the game's take, cold iron is simply wrought iron (as opposed to cast iron), and although it can't truly kill faeries ('''nothing''' can kill faeries), the merest touch of it will send a faery into a deep sleep for anywhere from hours to weeks.
* ''TabletopGame/{{Champions}}'' adventure ''The Coriolis Effect''. Ch'andarra and her daughter the Black Enchantress both take damage when touched by raw (cold) iron.
[[/folder]]

[[folder: Video Games ]]
* In ''VideoGame/FinalFantasyIV'' the Dark Elf is vulnerable to iron and has enchanted his cave to be heavily magnetic, requiring you to reach him without wielding anything metallic. When you reach him, at first it is a HopelessBossFight but [[spoiler:if you talked to Edward in the castle, he gives you a harp which breaks the spell, allowing you to wield metal]].
** [[spoiler:Or you can go to the one town that sells silver (i.e. non-magnetic) equipment beforehand. It's a bit of a trip, but worth it.]]
* Playing as a Mist Elf in ADOM will make you suffer damage with each turn you are in contact with iron or steel items.
* In ''Franchise/{{Pokemon}}'', [[ExtraOreDinary Steel-type]] attacks are super effective against [[OurFairiesAreDifferent Fairy-type]] Pokémon, and Steel-type Pokémon resist Fairy-type attacks.
[[/folder]]

[[folder: Webcomics ]]
* Elves in ''Webcomic/DragonMango'' are extremely vulnerable to iron, but through TrainingFromHell can [[CharlesAtlasSuperpower learn to resist it.]] Afterwards they use iron armors as a PowerLimiter. Half-Elves are completely immune to it, likely due to their human half's iron-based blood.
* Cold iron in ''NeverNever'' prevents Pookas from using any of their special abilities, including [[YourSizeMayVary changing size]] and [[WindsOfDestinyChange increased luck]].
* ''Webcomic/TalesOfTheQuestor'' makes extensive use of this trope. Although it claims "cold iron" is a mistranslation of "north iron" ie lodestone.
* In ''{{Webcomic/Roommates}}'' cold iron seems to be the default weakness of the fae, because, well, [[ClapYourHandsIfYouBelieve it's believed to be]]. It's literally one of the two known things to be able to injure the [[MonsterRoommate resident one]] (the other being a [[WeaponOfXSlaying magic sword specifically designed to hurt him and his subjects]]). There is no agreement in the comic what makes anything cold iron, though, but experience showed that steel swords don't count, but [[FryingPanOfDoom iron frying pans]] do.
[[/folder]]

[[folder: Web Original ]]
* Demons in Literature/TheSalvationWar have a deep rooted fear of Iron. It apparently is toxic and screws up their regeneration abilities. While it's never really explained why, [[HumansAreWarriors the Human forces]] [[CombatPragmatist are quick to]] [[DepletedPhlebotinumShells exploit it]].
* In the Literature/WhateleyUniverse, magical girl Fey is susceptible to cold iron (and synthetics) as soon as she gets her powers and changes into one of the true Sidhe. As she finds out the moment she picks up her mom's iron frying pan.
* Little One in ''WebVideo/TalesFromMyDDCampaign'' wields a Cold-Iron sword. Per standard D&D rules, it cuts through the defenses of any sort of Fey creature, which saves the party more than once.
* Cold Iron is described as an effective tool against [[TheFairFolk faeries]] in ''Literature/TheSaints''.
[[/folder]]

[[folder: Western Animation ]]
* In ''WesternAnimation/{{Gargoyles}}'', the Oberon's Children were all weak to cold iron, up to and including Oberon himself. This is utilized in a number of ways - iron chains to bind Puck and the Weird Sisters, an iron robot named Coyote to catch the mythical Coyote, and ringing an iron bell to take down Oberon [[WillfullyWeak when he agreed to use only as much power as one of his children for a contest]] (though when he was at his full power an ''iron harpoon to the chest'' only slightly injured him).
* In ''WesternAnimation/JusticeLeague'' and the next series, Hawkgirl's mace is made of "Nth metal" which is anti-magic. It's used to take down magic users, gods and extra dimensional beings. To everything else, well, it's big, metal and spiky and hits really hard.
[[/folder]]

[[folder: Real Life ]]
* In the life cycle of larger stars, when they run out of hydrogen in their core to produce energy, stars start fusing other elements in order to maintain itself. The star keeps on building layer after layer within the core fusing heavier and heavier elements, and getting less and less return. Fusing iron will give no energy return. A few days after it starts to make iron in its core, it will go supernova. So iron is the star killing metal.
[[/folder]]

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