A complete and bestial manifestation of the Vyrkos strain of the Soulblight curse, Vargskyr are Vampires whose bloodlust has either overcome them or have not fed for long enough that they have lost their sentience and become terrifying Undead vampiric beasts.  
At least one Vargskyr was found in the city of Ulfenkarn, ruled by the Vampire Lord Radukar the Wolf.  Furthermore, Radukar possessed the ability to transform humans into Vargskyr at will, should the victim have already been infected. 
Vargskyr are large wolf like creatures possessing immense strength and a limited intelligence. Though bestial in nature they can follow simple instructions, such as guarding a location . Those undergoing the transformation are weak to all sources of light, and become emaciated and weak.