Necromancer (quest nemesis)
The Necromancer, W, is the Elf quest nemesis in dNetHack. He is a wraith-like monster that guards the Palantir of Westernesse at the end of the dNethack Elvish Racial Quest for elven Nobles, Priests, Rangers, and Wizards.
The Necromancer has two weapon attacks, a sleep-inducing breath attack similar to the Nazgul, a life draining gaze, the ability to cast mage spells, and a claw attack that can steal the Palantir or the Amulet of Yendor from you. The Necromancer hates silver and possesses cold resistance, sleep resistance, poison resistance, and stoning resistance.
The Necromancer is a fairly simple quest nemesis: most roles should not have too much trouble with him, and silver arrows work well for elven Rangers in particular. Drain resistance or a means of blinding yourself (e.g. a blindfold) will protect you from his life-draining gaze, and the former property can also prevent him from draining your levels with his magic.
The "Necromancer" is an alias used to refer to Sauron as he appears in The Hobbit by J.R.R. Tolkien; Sauron also serves the titular chief antagonist of The Lord of the Rings, which confirms him to be the "Necromancer" of The Hobbit. The Silmarillion describes him as the chief lieutenant of the first Dark Lord, Morgoth.
Sauron rules the land of Mordor and has the ambition of ruling the whole of Middle-earth; he appears most often as a disembodied, flaming "Eye", though he is briefly seen in a humanoid form in Peter Jackson's film trilogy. Though Tolkien denied that absolute evil could exist, he stated that Sauron came as near to a wholly evil will as was possible.