Nightwalker

"'This creature looks like a humanoid giant, taller than a house and composed of pure darkness. It wears no clothing and has smooth, hairless skin and a genderless body.'"

Nightwalkers are human-shaped horrors that haunt the darkness, hailing from the Plane of Shadow. These mighty beings lurk in dark areas where they can almost always surprise the unwary. Their natural weapons are treated as magic weapons for the purpose of overcoming damage reduction.

Stats

 * Class levels: Undead 20
 * Huge, Extraplanar
 * Alignment: Chaotic Evil
 * Str: 38, Dex: 14, Con: 10, Int: 20, Wis: 20, Cha: 18.
 * AC: 33. 10 (Base) + 22 (Natural AC) + 3 (Dexterity bonus) - 1 (size modifier)
 * HP: 178
 * Feats: Weapon Proficiency (Creature), Cleave, Combat Expertise, Disarm, Power Attack, Great Fortitude, Improved Disarm, Improved Initiative, Darkvision
 * Attacks: Slam +23 melee (2d6+16)
 * Skills: Concentration 28, Hide 16, Listen 24, Lore 24, Move Silently 24, Search 24, Spellcraft 26, Spot 24
 * Special properties: Immunity: Disease, Immunity: Critical Hits, Immunity: Death Magic, Immunity: Level/Ability Drain, Immunity: Mind-Affecting Spells, Immunity: Paralysis, Immunity: Poison, Immunity: Sneak Attack, Damage Reduction: 15/+1 and alchemical silver.
 * Abilities (all as caster level 21): Aura of Fear, Cone of Cold, Confusion, Contagion, Finger of Death, Fear Gaze, Dispel Magic, Greater, Haste, Hold Monster, Invisibility, See Invisibility, Summon Greater Undead, Word of Faith