Fairies are dangerously cunning magical creatures that live outside the fillorian kingdom. They dwell within the same time and space as Castle Whitespire but in a separate plane of existence, within Castle Blackspire. They are known for their insidious terms, as well as their unconventional way of expressing themselves, resorting to riddles and puns.
Their appearance varies for each individual, but some elements are recurring, such as pointed ears. The fairies residing in Fillory boundaries are ethereal, with claws and disturbing, sinister eyes.
When Eliot agreed to participate in a duel against the Lorian King, Idri, to avoid a war between the two kingdoms, Margo sought the help of royal advisors, who mentioned the possibility of resorting to the fairies; These creatures, in fact, could have clean the Wellspring esnuring Elliot a constant resource of magic for his swordsman spells. When the emissary of the fairies came to court, he claimed that Eliot and Fen's unborn child were to be given to fairies as payment. Faced with the decision whether to save Elliot or the unborn child, Margo had to consent to the exchange, accepting the fairies' term.