Silver
I recall someone saying that werewolves being killed by silver was an invention of Universal studios. I've decided to prove you wrong.
I've traced stories where werewolves are harmed by silver as far back as 1716. Here's proof that silver killing a werewolf was not invented by the movie The Wolf-man.
The Werewolf of Jarnitz
A. Haas
In the vicinity of Jarnitz there lived a werewolf who had the ability to transform himself into all kinds of different shapes. This werewolf spent the nights stealing sheep from their enclosures, for in those days the sheep were kept at night in enclosures in the open fields. For several nights in a row the shepherd, armed with a loaded gun, had kept watch for the night robber. He had already hit the werewolf several times, as he had clearly seen, but the bullets seemed to have done him no harm, and he had escaped with his booty every time. Then the shepherd loaded his gun with bullets made of inherited silver, which never fail. Thus this time he would be successful.
Following his custom, the werewolf appeared again that night. But as he was approaching the enclosure, he immediately sensed that this time the shepherd might do him in. Therefore he quickly turned himself into a human, walked up to the shepherd, and said to him in a familiar tone, "You don't have to shoot me dead!" That so unsettled the shepherd that he lowered his gun, which he had been aiming at the intruder.
The werewolf never again dared to steel sheep from the Jarnitz enclosures.
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Source: A. Haas, Rügensche Sagen und Märchen (Stettin, 1903)
http://www.pitt.edu/~dash/werewolf.html#grimm214
And here's another...
The Werewolf of Hüsby
Karl Müllenhoff
In Hüsby near Schleswig there lived an old, stingy woman. She offered her farm hands but little to eat, although there was fresh meat every Sunday. The household wondered about this, because the old woman never bought any meat.
A young farm hand wanted to discover the woman's trick, so one day he hid himself in the hayloft instead of going to church with the rest of the household. Suddenly he noticed how the woman pulled out a wolf strap and put it around herself. She immediately became a wolf, ran out into the field, and soon came back with a sheep.
"If she can get meat that easily," thought the boy, "then she can be more generous with us. As the woman put meat into the pot, she sighed and said, as was her custom, "Oh, dear God, if only I were with you!"
The boy, pretending to be God, answered, "You'll not come to me for all eternity."
"Why not, dear God?"
"Because you put too little into the pot for your people."
"Then I'll do better."
"Yes, that's my advice to you."
From now on she put a much larger piece of meat into the pot. But the boy could not remain silent, and in the village he talked about what had happened. When on a Sunday morning the woman again turned herself into a wolf, the people were on guard. However, no bullet could harm her until they finally loaded a flintlock with a silver bullet. From that time to the end of her life the woman had an open wound that no doctor could heal. She never again showed herself as a werewolf.
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Source: Karl Müllenhoff, Sagen, Märchen und Lieder der Herzogtümer Schleswig, Holstein und Lauenburg, neue Ausgabe von Otto Mensing (Schleswig, 1921), no. 370.
For a German-language text of this legend, click here: Der Werwolf von Hüsby.
This legend was also published under the title "Die Frau mit dem Wolfsriemen" in Gundula Hubrich-Messow, Sagen und Märchen aus Schleswig (Husum: Husum Druck- und Verlagsgesellschaft, 1994), no. 14, p. 15.
Man is least himself when he talks in his own person. Give him a mask and he'll tell you the truth.