Silver bullet

A silver bullet is a bullet made out of silver. Silver is often considered a "pure" metal, which makes it anathema to certain types of creatures, such as werewolves. Some vampires are vulnerable to weapons made out of silver as well. Silver bullets can also be used to dispatch fallen angels as well.

The American western hero known as the Lone Ranger uses silver bullets in his six-shooters. They are something of a trademark for him, and he will often leave one behind at the scene of an incident to indicate his involvement.

Comics

 * Spirits of Vengeance 1