Dark Elves

According to elven legends, thousands of years ago a tribe of elves made a terrible bargain with Lolth, the Demon Queen of Spiders. They sought access to forbidden lore and made a pact with the demon, but the Emperor banished them from the The Empire . They were never seen or heard from again.
In some tales, the banished elves fled south, across the the Celestial Sea and beyond the Desert of Bones. In other tales, they travelled east, or west.
In the lore of the Gnomes, especially that of the Deep Gnomes, they hid far underground. There, the Deep Gnomes believe that they worship Lolth in grotesque ceremonies and rituals. Some of the wilder Deep Gnome accounts talk of elves with "night-black" skin and even creatures who are half elf / half spider.