The Wrong

You must stay well away from the trees that make up the border between Faerie Wood and the outside, lest you be ensnared by The Wrong. It will snatch you up and away, taking delight in feeding on your magical blood.
-Lullaby, sprite mother

Summary

The Wrong is a twisted elf, or perhaps fae, that has been warped and corrupted over the centuries. It has acquired a deep hatred for the sylvan folk as well as an insatiable hunger for their blood. It is said that drinking the blood of one of these creatures gives The Wrong more power, and, if the beast imbibes enough, it will allow it to get past the magic protecting Faerie Wood so that The Wrong may destroy all who live there.

Historical Basis

The fae, while possessing great creativity and imagination, tend to be bright and happy creatures. This makes it difficult for their minds to dwell long on darkness and evil, and so any tales they might tell or songs they might sing about such things are usually tinged with some light.
After the Hellgate, the sylvan folk of the Faerie Wood were desperate to find a way to keep their children from venturing outside the magical protections of their borders. It was decided that they would warn them away with tales of some creature that would target them in horrendous ways. Their minds did not go to the fiends, however, and instead focused on that which they would most fear: the corruption of an elf or one of their own.
Many names were suggested and discarded, their imaginations running freely with such choice monikors as The Warped Blood Sprite (quickly discarded as being too specific) and Evil Dark Fae Eating Thing (while the pixie Walnut was very excited about this name, the more practical centaur Steadfast put the kibosh on it, stating that it had too much potential to change from day to day). They finally settled on the short and simple term of The Wrong, which conveyed the idea they wanted without being too elaborate.

Spread

The myth has been mostly contained in the Faerie Wood, although it has some play in other sylvan or elven forests.

Variations & Mutation

This one varies almost from one telling to another, at least in the case of specifics. They had originally intended it to be vague and unspecific, but each fae who tells the tale tends to put his or her own spin on it leading to some quite interesting descriptions that are always entertaining. Very seldom does a fae give the same description more than once.

In Art

There are pictures and sketches of this throughout the Wood, although they make it no further. The sprites and pixies especially enjoy coming up with these and proudly show off their "knowledge" and talent. No two pictures are ever the same, even those created by the same fae. After all, no one has gotten close enough to see this vile creature and survive to describe it.