The article presents child-threatening mythical creatures, their expressions and functions in Lithuanian folklore. Threats of the mythical world can be divided into two groups: real and constructed threats. The ones of the first group, real threats, are perceived as threats to children by adults. Real threats arise from two types of representations of the mythical world: mythical creatures and mythologised persons. The second group, constructed threats, is the is the phenomenon in which adults use folklore narratives to evoke fear in children, but adults do not perceive those narratives as real threats. Three types of folklore genres were used to frighten children: fairy tales, folk legends, and short, frightening expressions. This article focuses on the latter. The research analyses Lithuanian customs, beliefs, and narratives from the late 19th century and the first half of the 20th century.