Werewolves as a folkloric myth is largely concentrated around Eastern Europe. The lore goes that having been bitten by one, a person turns into a wolf come the full moon. They could be killed by silver bullets, according to a later addition to the myths. One credible explanation is that it is a way to account for out of ordinary behavior - 'It wasn't him - he turned into a wolf, and that was what killed that woman.' It's easier to take if the capacity for wrongdoing is becuase of a curse or becuase one is evil - it sheilds us from the understanding that we're all capable of such acts.