A fairy in a tree
A fairy was a mythological creature from Earth folklore that was similar to a pixie. Fairies were typically described as Human in appearance and having magical powers. They would sometimes replace Human children with a Changeling. Notable fairies include Titania, Oberon, and the Tooth Fairy. (VOY: "Barge of the Dead")
Titania, Bottom and the Fairies, a painting by Earth artist Henry Fuseli, depicted fairies surrounding Titania and Nick Bottom (who had been turned into a donkey) from the play A Midsummer Night's Dream. An illustration of this painting was found in Captain Picard's edition of The Globe Illustrated Shakespeare: The Complete Works. (TNG: "The Offspring")
When an away team from the USS Enterprise-D was trapped in 1893 San Francisco, the team members claimed to be actors having performed A Midsummer Night's Dream in Milan, London, and Paris. Doctor Crusher played a fairy. (TNG: "Time's Arrow")
The song "Oh My Darling, Clementine" described the title character as being like a fairy. (VOY: "Equinox, Part II")