A Fairy, also known as fay or fae, is a type of mythical being or legendary creature in European folklore, a form of spirit, often described as metaphysical, supernatural, or preternatural. Fairies resemble various beings of other mythologies, though even folklore that uses the term fairy offers many definitions.

Much of the folklore about fairies revolves around protection from their malice. Although in modern culture they are often depicted as young, sometimes winged, humanoids of small stature, they originally were depicted quite differently: tall, radiant, angelic beings or short, wizened trolls being two of the commonly mentioned forms.

One common theme found among the Celtic nations describes a race of diminutive people who had been driven into hiding by invading humans. When considered as beings that a person might actually encounter, fairies were noted for their mischief and malice. Fairies are generally described as human in appearance and having magical powers.

Folklorists have suggested that their actual origin lies in a conquered race living in hiding, or in religious beliefs that lost currency with the advent of religion. These explanations are not necessarily incompatible, and they may be traceable to multiple sources. Much of the folklore about fairies revolves around protection from their malice, by such means as cold iron (iron is like poison to fairies, and they will not go near it) or charms of rowan and herbs, or avoiding offense by shunning locations known to be theirs.

In particular, folklore describes how to prevent the fairies from stealing babies and substituting changelings, and abducting older people as well. Many folktales are told of fairies, and they appear as characters in stories from medieval tales of chivalry, to Victorian fairy tales, and up to the present day in modern literature. Diminutive fairies of one kind or another have been recorded for centuries, but occur alongside the human-sized beings; these have been depicted as ranging in size from very tiny up to the size of a human child.

Even with these small fairies, however, their small size may be magically assumed rather than constant. Some fairies though normally quite small were able to dilate their figures to imitate humans. Wings, while common in Victorian and later artwork of fairies, are very rare in the folklore; even very small fairies flew with magic, sometimes flying on ragwort stems or the backs of birds. Nowadays, fairies are often depicted with ordinary insect wings or butterfly wings.

n some folklore fairies have green eyes and often bite. Though they can confuse one with their words, fairies cannot lie. They hate being told 'thank you', as they see it as a sign of one forgetting the good deed done, and, instead, want something that will guarantee remembrance.

In folklore, they are variously regarded as a "natural" but hidden species, as spirits of the dead, or as descendants of either fallen angels or demons. Fairies are generally described as human in appearance and having magical powers. Their origins are less clear in the folklore, being variously dead, or some form of demon, or a species completely independent of humans or angels.

Another theory is that the fairies were originally worshiped as minor goddesses, such as nymphs or tree spirits.

A Fairy can be of any element, and can be either light or dark. Fairies are often seen as helpers of several things. Being as the seasons change Fairies often help it, they help wake plants and trees from slumber as well as animals and insects. Such creatures will often only show themselves to children and even than that is rare.