Silver is a metal with strong supernatural properties, and can be used to battle various supernatural creatures, although it does not affect higher rank beings (angels, Horsemen and so on). It is part of the ritual to create more bullets for the Colt.
Creatures that silver affects
- Djinn - A silver knife, if dipped in lamb blood, will kill a Djinn.
- Fairies - Silver will burn the skin of a dark Fairy, if it makes contact.
- Jefferson Starships - A silver knife can be used to kill a Starship, but only if the head is cut off.
- Lamia - A blessed silver knife, will kill a Lamia
- Pishtaco - A silver knife will kill a Pishtaco.
- Revenant - Silver has negative effects on Revenants.
- Shapeshifters - Capable of killing shapeshifters, however the alpha shapeshifter is immune to this weakness.
- Skinwalkers - The "cousins" of werewolves, silver is so far the only weapon that can kill them. Silver chains will also restrain them.
- Vetala - A silver knife (when stabbed and twisted once), is the only thing that will kill a Vetala.
- Werewolves - Can be killed by silver to the heart. In one case, decapitation through silver buckshot killed a werewolf.
- Wraith - To touch silver will burn a Wraith's skin. To pierce one through the heart with silver will kill it.
- Zombies - A silver stake will "kill" certain Zombies. Silver bullets will hurt them, but not kill them.
- Edward Trenton's Species - Although his kind still surrounded by mystery, one of them could be killed by a steel knife coated by silver.
- Nachzehrer - Can slow them down, but won't kill them.
- Whispers - According to Castiel, silver along with decapitation will kill a Whisper.
- Sleipnir - A sliver bullet to the right shoulder of the god Sleipnir was able to wound and effectively defeat him.
- Gorgon - Gorgons can be killed by being beheaded with a silver blade.