The creatures known as void elves are obscure to a degree that there aren't even any urban legends or myths about them.
Even noting their denomination of elf is disputed and originates more from a preconception of calling mythical and mystical humanoids "elves" than actual certainty about their relation to other elf races.
The void part of the name is also based in uncertainty; there are those that claim that these beings hail from deep underground, or perhaps underwater, or even the very void between the stars.
What is known is that they seem to have a general disdain and avoidance of other races, and that they seem to have some innate psionic abilities.