The Vaulkhar are the Dark Elf generals of the Black Cities of Naggaroth, charged with leading the armies of each city. The Vaulkhar are the ones who assist Malekith during the various invasions of Ulthuan, as well as protect the cities from Chaos marauders, monster attacks, and strikes from the other cities. A Vaulkhar rarely leads from the front, instead using fear and intimidation to keep his troops in line. This fear stems from the fact that each Vaulkhar is granted his or her title by Malekith himself, and as long as they please the Witch King they will benefit from his protection.
Sources[]
1. Warhammer Armies: Dark Elves (8th Edition)