Vampire
Vampires are so far removed from other varieties of undead it seems almost unreal. What grants them their longevity? How do they retain such great intelligence? Beyond their sallow complexion and drawn features, why do they not decay and decompose as their ghoulish siblings do? The study of vampiric nature is one long list of unanswered questions, each new study adding yet more to the ever-growing pile.
As said before, a vampire's greatest strength is its resemblance to a living man, both in mind and body. Thanks to this, vampires are known for residing comparatively close to normal towns and villages far more than other undead. Some have even been known to keep their lairs within these communities themselves! Despite their resemblance however, there are many telltale signs of vampirism: Unnaturally pale skin, long and distinctive fangs, an aversion to sunlight, and much more besides. In an effort to avoid close inspection, some vampires are known to masquerade as men of wealth, often cloistering themselves in remote locations to discourage prying eyes.
But perhaps the most astonishing thing regarding vampires is their propensity for alliance and familial relationships. No other undead being even approaches matching the incomprehensible tangle of clans, broods, families and bloodkin that vampires create for themselves. It is for this reason that vampires often end up becoming rulers of lesser undead themselves, commanding them as a normal necromancer would. So, in turn, treat them as you would a necromancer - with cold steel.