Fairies
Fairies are mythical creatures in many forms. The lore (mostly Irish or Scottish) on them suggests that they are extremely diverse, the category of "fairy" includes goblins, gnomes, elves, leprechauns, and also there are popular beliefs that they are either undead, or elementals, maybe etheral creatures, or even fallen angels.
They also appear in folktales as pagan dieties, and they seem to be similar to whom the Celtic folklore calls "the hidden people".
In Supernatural the guys encounter four(or maybe five) kinds of them.
In 6.09 Clap Your Hands If You Believe:
1. A Tinkerbell-like creature attacks Dean in the motel. This kind - according to the folklore - is the most common fairy.
2. There are little elves working in the watchmaker's workshop.
3. Also, there's a Redcap following Dean, finally attacking him in his jail cell. These fairies are considered to be dangerously homocidal, they are known for mercilessly killing travellers who trespass their territory. They soak their hats in the blood of their victims, that's why it's red. The lore claims that they have to kill regularly because if the blood dries on their hats, they die.
4. The leprechaun, who is a kind of covert agent in the human world, operating as a UFO-specialist to avoid detection.
The Changelings are also claimed to be fairies in Western European folklore.
