|“||Don't worry. Most creatures I meet can't get it up for iron. It's a common monster problem.||”|
— Dean to Elias Finch
Creatures that Iron affects
- Acheri - Contact with iron will force an Acheri to dissolve and temporarily retreat.
- Demons - Touching an iron will burn low level demons.
- Fairies - All fairies are weakened by iron, although powerful ones like Leprechauns can shrug it off.
- Ghosts - Shooting or stabbing a ghost with iron will temporarily make the ghost disappear. Ghosts also can't cross iron. Sam and Dean consider cold iron to be the best way to repel vengeful spirits. If a person possessed by a spirit touches something made of pure iron the spirit will be forced out of the human.
- Hellhounds - Iron can harm them as demonstrated in the episode "Abandon All Hope..." in which Ellen and Jo sacrifice themselves to attempt kill the attacking hellhounds by detonating a propane bomb filled with iron nails and rock salt.
- Leshi - The only way to kill a Leshi is to cut off its head with an iron axe.
- Phoenix - Iron burned the Phoenix's skin, and it couldn't touch Iron, or if imprisoned by it, escape.
- Shtriga - Consecrated Iron bullets are the only known thing that can kill a Shtriga.
- Witches - Although Iron doesn't hurt witches, it blocks their powers, as Dean used it to restrain James Frampton and he was unable to escape from them or astral project. Olivette was also bound by Iron when Crowley captured her for his mother Rowena and was left powerless.
- In many cultures and religions, iron is something that keeps evil and/or supernatural forces at bay.