Vaul
Vaul is the Eldar god of smithing. His name seems to be attached to other Eldar terms related to forging and production; for example, Mars (and possibly other Forge Worlds as well) is called "the Vaul-moon" by the Eldar.
Vaul was a pretty nice guy; not only did he forge the spirit stones that allowed Isha and Kurnous to speak with the Eldar after being forcibly separated from them by Asuryan (and later allowed the Eldar to protect their souls from Slaanesh), he spoke up for them when they were imprisoned by Khaine for doing so. When Khaine demanded one hundred mighty blades in exchange for the two gods' freedom, Vaul agreed right away. When Khaine got angry and started the War in Heaven because he only got ninety-nine blades by the time the deadline was up, Vaul forged the last one, made it better than the rest, and faught the Eldar God of War.
Unfortunately, like all nice things in the Warhammer 40,000 universe, Vaul was just too good to stick around; he was ultimately defeated by Khaine, who crippled him and chained him to his anvil for his trouble.
Like the rest of the Eldar pantheon (except for Khaine, Cegorach, and Isha), Vaul met his end when he got eaten by Slaanesh during the Fall of the Eldar. That said, some of his creations survive to the 41st Millennium; the spirit stones are the most numerous of these, while the "Talismans of Vaul," otherwise known as the Blackstone Fortresses, are the most powerful.
The Vaul family is an old family line that has migrated all across the world over the centuries, and as the name Vaul has spread, it has evolved making it's history challenging to uncover. This Vaul research page contains the accumulated history of the Vaul last name made up of user-submitted content from other AncientFaces users. Vaul family history has a rich and complex origin whose details can be pieced together by Vaul family members.