Genasi, Planetouched, Native Outsiders...?

[ThinkMinty]

So, what book(s) are the Genasi in? They're those elemental people with the elemental hair, some kind of native outsiders or something.

[Vhaidara]

I know it's a Faerun book. Monsters of Faerun, I think? They were definitely introduced as a monster entry

[DrMotives]

They're in both Monsters of & Races of the Faerun books.

[Marlowe]

The useful stats for them are in Faerun Campaign Setting; there's a listing for them in Races of Faerun, yes, but it's all fluff and no crunch.

The stats for a couple of the genasi sub-types in Monsters of Faerun are also different from their stats in the Campaign Setting (the Monsters entry has more extreme stat adjustments, though no net gain or loss), so make up your mind up which book you're using.