Zuggtmoy, the Demon Queen of Fungi

The Demon Queen of Fungi, Lady of Rot and Decay, Zuggtmoy is an alien creature whose only desire is to infect the living with spores, transforming them into her mindless servants and, eventually, into decomposing hosts for the mushrooms, molds, and other fungi that she spawns.
Utterly inhuman, Zuggtmoy can mold her fungoid form into an approximation of a humanoid shape, including the skeletal-thin figure depicted in grimoires and ancient art, draped and veiled in mycelium and lichen. Indeed, much of her appearance and manner, and that of her servants', is a soulless mockery of mortal life and its many facets.
Zuggtmoy's cultists often follow her unwittingly. Most are fungi-infected to some degree, whether through inhaling her mind-controlling spores or being transformed to the point where flesh and fungus become one. Such cultists are fungal extensions of the Demon Queen's will. Their devotion might begin with the seemingly harmless promises offered by exotic spores and mushrooms, but quickly consumes them, body and soul.
Sharing a layer of the Abyss with Juiblex, the Faceless Lord, plus their mutually insatiable hunger, has made the two demon lords eternal enemies, each devoted to destroying and ultimately devouring the other.