Slavic uses the term vlko-dlak (Polish wilkołak, Czech vlkodlak, Slovak vlkolak, Serbo-Croatian вукодлак – vukodlak, Slovenian volkodlak, Bulgarian върколак/vrkolak, Belarusian ваўкалак/vaukalak, Ukrainian вовкулака/vovkulaka), literally “wolf-skin”, paralleling the Old Norse ulfhéðinn. However, the word is not attested in the medieval period. The Slavic term was loaned into modern Greek as Vrykolakas. Baltic has related terms, Lithuanian vilkolakis and vilkatas, Latvian vilkatis and vilkacis. The name vurdalak (вурдалак) for the Slavic vampire (“ghoul, revenant”) is a corruption due to Alexander Pushkin, which was later widely spread by A.K. Tolstoy in his novella The Family of the Vourdalak (composed in French, but first published in Russian translation in 1884).
In Hungarian folklore, the werewolves used to live specially in the region of Transdanubia, and it was thought that the ability to change into a wolf was obtained in the infant age, after the suffering of abuse by the parents or by a curse. At the age of seven the boy or the girl leaves the house and goes hunting by night and can change to person or wolf whenever he wants. The curse can also be obtained when in the adulthood the person passed three times through an arch made of a Birch with the help of a wild rose’s spine.
The werewolves were known to exterminate all kind of farm animals, especially sheep. The transformation usually occurred in the Winter solstice, Easter and full moon. Later in the 17th and 18th century, the trials in Hungary not only were conducted against witches, but against werewolves too, and many records exist creating connections between both kinds. Also the vampires and werewolves are closely related in Hungary, being both feared in the antiquity.
Among the South Slavs, and also among the Kashubs of what is now northern Poland, there was the belief that if a child was born with hair, a birthmark or a caul on their head, they were supposed to possess shape-shifting abilities. Though capable of turning into any animal they wished, it was commonly believed that such people preferred to turn into a wolf.
Serbian vukodlaks traditionally had the habit of congregating annually in the winter months, when they would strip off their wolf skins and hang them from trees. They would then get a hold of another vulkodlak’s skin and burn it, releasing from its curse the vukodlak from whom the skin came.