Clavicus Vile, also known as the Prince of Trickery and Bargains, the Master of Insidious Wishes, and Nycot to some Second Era cultists who lacked the ability to read Daedric script, is a Daedric Prince whose sphere is the granting of power and wishes through ritual invocations and pacts. He is seen as one of the more "sophisticated" of the Daedric Princes, and often appears in the guise of a jovial Skaafin, a race of horned Daedra that inhabit the Fields of Regret, his realm in Oblivion.
Clavicus finds eternity to be "boring", so he finds entertainment in watching mortals and occasionally meddling in their affairs. He has been known to be the patron to vampires, gracing them with social stature, reason and savvy, allowing them to not only live among regular mortals, but to hold powerful positions in society. However, not all of Vile's machinations are necessarily insidious; he has been known to reward those who, on his direction, eliminate threats to the general public (while still serving his own interests).
Vile is rarely seen without his loyal companion, Barbas. Barbas typically assumes the form of a dog, but is also known to appear as a Scamp named Creeper. The two are so close, Barbas is almost universally depicted alongside his master in artwork and statuary. In fact, Vile has been known to store up to half his power within Barbas. These facts have led to speculation that the pair are, in fact, two halves of the same being.
For more information, see the main lore article.