Nickelodeon

A boxlike creature that sings as it consumes nicklepedes. Harmless, if you can stand the noise.

Nicklepedes

Ferocious insects five times as big as centipedes, with pincers of nickel. They attack anything moving in shade or darkness, but can not function in direct sunlight.
'See Pede's for more info'

Night Mares

Dream equines who deliver bad dreams to deserving sleepers. They have a bad reputation, but are only doing a necessary job. They travel only at night, and their hoofprints are maps of the moon with the moon features associated with individual mares highlighted. Included in the herd are Mares Australe, Crisium, Frigoris, Humerium, Necaris, Nubium and Vapors. Mare Imbrium (Imbri) figures prominently in Xanth history. Night mares can travel almost anywhere, and evidence of their presence has been noted in nocturnal Mundania.

Nix

A sprite, part human, part satyr, part fish. When he says "NIX" water turns to ice; when he says "NOX" it becomes too thin to swim in but too thick to breathe.

Nymphs

Lovely nude young women, counterpart to the male Fauns. There are a number of varieties. Dryads live in trees, having leaf green hair; Naiads are water Nymphs, with seaweed hair; Oreads live in mountains. Some are general-purpose Nymphs living elsewhere. Jewel the Nymph is in charge of gems.