The aranasi are a race of arachniddemons. Their origins are not fully understood - scholars who have studied the Burning Legion speculate that they are the remnants of a forgotten race on a world long ago conquered by the armies of Sargeras.
Some aranasi appear to look like typical spiders, while others have a partially humanoid appearance resembling nerubians or fire spiders, and some have an even more humanoid appearance, standing on two legs with wing-like structures on their backs. At least some aranasi have potent venom sacs that secrete violent toxins.
Pools of an orange fel-like substance can be found in their lairs, though what this is is unknown. Near the Lost Temple it is "slag" (Cooling Slag Globules come from it), but unrelated to the aranasi.
This article or section includes speculation, observations or opinions possibly supported by lore or by Blizzard officials. It should not be taken as representing official lore.
Broodmother aranasi appear to lay clutches of eggs that give birth to spiderlings. There are also aranasi, such as King Voras, who use the same model as Beth'tilac and other partially humanoid-looking fire spiders. It is thus possible that the spiderlings grow to become full spiders, then into an intermediate half-humanoid half-arachnid state, and then into adult and humanoid aranasi. However, since no male humanoid aranasi has been witnessed, it is also possible that males remain at a more bestial-looking stage like King Voras, while females grow into humanoids.
Rancora may be the aranasi homeworld. Lady Dacidion is an aranasi coming from that world through a portal, which is described as "a landscape of festering pools and skittering death" which fits what is seen of aranasi territories, so at the very least they have a prominent presence on it.