Aside from the large number of purely imaginary beings which people the regular folktales of Europe and western Asia, and which the tellers normally recognize as unreal, there exist in every country a considerable number of such beings, human or animal in form, devoutly believed in by both story teller and listener. It is, of course, not easy to draw a sharp line between the creatures of fiction and of actual belief. But psychologically there is a great difference, for the creatures of belief are a part of the unlettered man's view of the natural world.

Each country has its own varieties of such beliefs. Many of them are doubtless related to those of neighboring lands, but exact equations of similar imaginary creatures is usually dangerous, or at least inaccurate. Each country has its own favorite groups. The sidhe, or kindly fairies, of Ireland; the terrible baba yagas of Russia; the malevolent glaestigs of the Scottish High lands; the jinns of the Near East; and the rakshasas of India—these creatures set the tone for the whole world of supernatural beings which they dominate.

In spite of these striking regional differences, there are no definite cultural boundaries, and many of the concepts relating to supernatural creatures are found with little change over whole continents, and sometimes, indeed, over the whole earth. Even when examining such widespread beliefs, however, we must always remember how hard it is to know when creatures of popular imagination merely have some feature in common and when they are actually identical.