A drekavac (The yeller, drek, drekalo) is a creature of the night and graveyard, originating from south Slavic mythology. It is said to come about from the soul of a dead unbaptised child. Some believe it can only be killed or laid to rest if its soul finds peace; baptism being an accepted method to achieve this.

Many forms have been attributed to the drekavac, it may be possible that it switches between these forms. Those of a bird, dog, fox or a slender bodied baby with an out of proportion head have all been given. A reason for this may be the belief that when seen as a baby the drekavac predicts death but when seen as an animal it predicts cattle disease. Though another explanation for the variation may be different variant types for different regions. Features that remain constant are its height being above 1 metre and its horrifying scream.

Its screaming, mainly heard coming from the graveyard, is said to be a cry for baptism. Though in some places, should it scream outside a house all night, one lodger from the house will die. Many explain that the drekavac has long fur and every time it steps on that fur it will let out a scream of pain.

Other vile acts, besides its terrible scream, include, falling on a person, or allowing its shadow to cross a person's. In either case the victim will soon fall ill and die.

The people of Serbia and Bosnia are of the opinion that one will only encounter a drekavac if one has a dream of a drekavac. If this is the case then death is within the drekavac's power through strangulation of the subject while they lie asleep in bed though it will only target those who have mistreated it in life. This is in direct contrast to the belief that the drekavac will not bother its parents.

For defence against the drekavac a dog must be obtained for it is known the drekavac is afraid of them. It also dislikes sunlight, which is why a drekavac's screaming is usually only heard at night or through the fog.

The drekavac is generally seen as a lonely, solitary creature but tales have been told where a pack of drekavacs have appeared. Where upon the pack will live in a cave or tunnel.

Among Slavic rural communities the drekavac is used as a 'bogeyman' equivalent to scare children into obedience. Despite this well known method, true belief in it can exist in some adults where upon some attest to having corpses of the creature.