fairy

English fairy is an alternative form of fay, a noun denoting a kind of supernatural being, often small in size. Fay was borrowed into English from Old French fae or fée with the same meaning. French fae/fée is itself derived from Latin fata, a plural noun denoting the Fates, the three sisters who draw out, measure, and cut the thread of life.

I like fairy because it shows how an ancient cosmic concept like the Fates persisted in and was modified by a new world-view. In their new (diminutive and demoted?) form, fairies no longer have the power of the Fates, but every now and then we still see them in threes, as with the trio of fairies in Sleeping Beauty: Flora, Fauna, and Merriwether.

Sources: Chambers Dictionary of Etymology and the OED