Fey

Fey can be found throughout the Universe. Though some worlds have an easier time seeing or having them visit.

The Most Notable is Worlds of the Fey.

Fey or Fay

Historically, Fey are a type of Fairy, or a different word. They are found in Folklore and take on a spirit like form. These are very common in many Fantasy settings. Different writers use them in a wide variety of ways. Some cases are beings such as Dryads, Water spirits; Kodoma(Japanese folklore), can also be considered fey, or at lease fey like.

I do keep with this definition of Fey/fay. However, I use the word Fey to express a ethereal being that does not naturally exist in any mortal realm, IE originates in the Mystic Realm. Nymphs(Water, Fire, nature, and so on) are considered to be Fey, while Merfolk, elves and other more fantasy like beings or creatures are not Fey.

The more sentient beings are normally referred to as Feylings, that would be things like Water Nymphs which tend to sources of water, keeping them clean and rot free.

Almost any Fey can be found in other worlds as well as in Worlds of the Fey.