Drekavac comes from the souls of children who have died unbaptized.
The creature is not consistently described. One description is that its body is dappled, elongated and thin as a spindle, with disproportionately large head; yet another is that it is some kind of bird; a modern find of supposed drekavac body looked like a dog or a fox, but with hind legs similar to those of kangaroo. It may also appear in the form of a child and call for people passing near the cemetery to baptize it. The one feature everyone agrees about is its horrifying yell.
Drekavac could be seen at night, especially during the twelve days of Christmas (called unbaptized days in Serbo-Croatian) and in early spring, in time where other demons appear most often. In the form of the child it predicts someone's death, but in the form of the animal, it predicts cattle disease. Drekavac rarely bothers its parents, as it is afraid of dogs.
Drekavac is often used as a child scare, in a similar way a banshee is in the West. It is probably more useful than banshees in rural areas, as children surely sometimes hear a sound of some animal and attribute it to drekavac, thus convinced it really exists; which would then probably prevent them from wandering far from home. In the cities, however, belief in it has faded, and Baba Roga, which more closely resembles western bogeyman, is much more used.
Though the creature is used as a scare tactic for children, there are adults who do believe in its existence. According to the guide of a reporter of Duga magazine, numerous villagers on the mountain of Zlatibor report seeing it, and almost everyone reports hearing it. In 1992, it was reported that in the Krvavica River the villagers found remains of an animal unlike any known, and claimed it was a drekavac. It looked like a dog or fox, but with hind legs similar to a kangaroo. A more recent encounter is from 2003, in the village of Tometino Polje near Divčibare. A series of attacks on sheep took place, not unlike those in other parts of the world attributed to chupacabras, and some villagers concluded that they must have been perpetrated by a drekavac. Others think it could not have been a drekavac because they have only heard the yells during the night, and the sheep were mutilated during the day. In September 2011 a horrifying yell and unverified encounters with strange creature, claimed to be drekavac, were reported in villages around Drvar in western Bosnia.
It´s also seen or heard in some small villages in Croatia and Serbia. Locations of the sightings include: Village Gornja Dragotinja
Village Tometino Polje (Tomet's field)
Neretva County, Croatia
Bukavac, recorded in Srem, a six-legged monster with gnarled horns that lives in water, coming out of it during the night making noise, and to try to strangle people and animals.
Jaud (pronounced [jaud]), similar to drekavac, from a vampirised premature baby.
Nav, the soul of dead child that died before its third age.
Plakavac, recorded in Herzegovina, is a small vampire, a newborn strangled by its mother, which will rise from its grave at night, return to its house and scream around it, but otherwise can't do any harm.