History Main / ColdIron

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". Sometimes it's got something to do with ferromagnetism, or related to iron's nuclear stability, or its resistance to rust.

* ''ComicBook/AstroCity'' invoked this during the climax of "Things Past". The destruction of the BigBad's base led to Steeljack accidentally breaking one of the various magical trinkets TheCollector had amassed, this one being the prison of seven malevolent spirits known as The Seven Sisters. Unfortunately for them, Steeljack's power comes from being coated with [[ChromeChampion a semi-organic steel alloy]], meaning that his entire ''body'' is cold iron. In the ensuing battle, Steeljack destroys five of the sisters before the remaining two flee.

* ''ComicBook/LegionOfSuperHeroes'': In the {{Elseworld}} story ''Superboy's Legion'', Ferro Lad 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.

** ComicBook/IronMan is not literally iron,[[note]][[Film/IronMan1 it's actually a gold-titanium alloy!]][[/note]] but just calling himself "Iron Man" is apparently reason enough for Malekith to call down TheWildHunt on him - granted, this was mostly a sign of how monumentally petty and casually sadistic he is (one of the Rings of the Mandarin is trying to influence him that way, it finds out he's EvilerThanThou, and he does it anyway). While Tony's usual suits are not iron, Malekith still ends up getting more than he bargained for after he provokes Tony (newly discovered to have been adopted) with stories about what Dark Elves do to Changelings. Tony has his ally send him a custom suit made entirely of iron complete with huge wrist-blades, a harpoon gun and a combination of iron filings and fans, then promptly goes on a rampage so vicious that he scares everyone, from his ally, to ordinary Dark Elves, to Malekith himself, who eventually ends up giving Tony the Mandarin Rings he's collected and a magically binding oath to send him back to Earth just to get Tony out of Svartalfheim... well, and also to save him from the other Mandarin Ringbearers, who are quite unhappy with Malekith at the moment.[[note]]This takes place during the "Rings of the Mandarin" arc in the 2013-2015 run; the Cold Iron Armor first appears at the end of issue #24.[[/note]] Afterwards, the Dark Elves start using him as a bogeyman for their children (which Malekith actually considers a plus), and it gets a CallBack during ''ComicBook/WarOfTheRealms'' when Malekith makes a point of avoiding Tony and manipulating a dragon into going after him.
** In ''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. {{Lampshade|Hanging}}d 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]]).
** [[Characters/MarvelComicsLogan Wolverine]]'s adamantium claws also count, since adamantium is a steel alloy. In one story he was able to easily dispatch some {{yo|ukai}}kai, but the big bad was instead vulnerable to [[spoiler:gold]]. Prior to that fight Wolverine had dipped one of his claws in [[spoiler:gold]] and kept it retracted until the critical moment.

* ''Literature/MaledictionTrilogy'': Cold iron is the only thing that can cause lasting injuries to trolls and limit their magical power. In addition, human world is full of iron, so trolls who spent too much time on it could not return to their own world and lost their immortality due to iron in their blood.

* Literature/ArsGoetia [[http://www.esotericarchives.com/solomon/goetia.htm#andromalius tells]] that you should [[SummoningRitual craft the demon's seal]] in specific metals [[DemonLordsAndArchdevils by rank]] (Kings in Gold, Marquises in Silver, Dukes in Copper, etc.). As for the Counts/Earls, associated with Mars and [[MagicPrerequisite the Tuesday]] and, by extension, to Iron, the grimoire asserts you should use Silver and Copper instead. Several occult writters agree it's due this very trope in effect[[labelnote:*]] and [[SchmuckBait some go on and say]] you should [[WeaksauceWeakness spare the iron]] to, hm, [[BullyingADragon "discipline"]] uncooperative spirits, like the punishments already [[RitualMagic ascribed in the Goetia ritual]] were not enough[[/labelnote]].

* {{Discussed}} in the eponymous short story of ''Literature/InsteadOfThreeWishes'' -- although iron isn't directly harmful to the Fae, a sufficient quantity of it does repulse or frighten them. The only example actually ''seen'' in the story is when the elf Prince Mechemel is trapped in the middle of a crosswalk while swarms of of steel (an alloy of iron) vehicles rush past.

* ''Literature/ThePerilousGuard'': Zigzagged. The cold iron cross a village woman gives Kate doesn't hurt the FairFolk, but it does hurt Kate when she cuts her hand with it, preventing her from [[spoiler:falling into an enchanted sleep]].