Many of the modern myths of werewolves originated from this film, such as a person becoming a werewolf through a bite, the only way to kill a werewolf is with a silver bullet, and werewolves and their victims being marked with pentagrams. Some are taken from the earlier, unsuccessful werewolf movie Werewolf of London (1935) (which also made them up out of whole cloth), and others are original concepts created by writer Curt Siodmak. Actual werewolf folklore is extremely varied; in some, one became a werewolf by being cursed or by making a pact with the devil, could turn at any time, and were mortal and could be killed by conventional means. Later films added the detail of werewolves being immortal; again, an invention of Hollywood, and basically an excuse to keep bringing the character back for sequel after sequel.