I don't know where else to put this because I can't find the newest WM thread on undead anywhere.
[sblock]Mindless undead
Skeletons & Zombies - these are not about the disposition of the creature, but about the state of the corpse when animated. Animated is the key word here. They are thralls to the animator. However, unique varieties can be fun as the two mentioned. More intelligent necromancers may armor their skeletons and program them to fight fairly well. They might infuse them with fire or ice, as was said, or other features. All of which, of course, costs.
Zombies could be due to a zombie plague. Perhaps they do retain a bit more remembrance of their life than the empty headed skeletons? Perhaps Speak with Undead still works on them? Or Gentle Repose? Perhaps they aren't all lumbering corpses? Speedy zombies have been popular, so have those who hunger desperately for brains. For one thing, as actual rotting corpses they are easier to disease to add yet another danger to those encountering them.
The key for both of these monsters (and perhaps all) is to leave their definition undefined just enough to allow space for DMs to homebrew in their own particulars and varieties. It's more fun when there is room for fresh detail still rather than a road that's been tracked over to near featureless.
Ghouls & Ghasts - These are based on a central defining trait of elves. They are all previous humans demi-humans, or humanoids, but only ghasts were previously elves. Why is this? Give some examples rather than the definitive answer for everyone.
These blokes aren't dumb, but overwhelmingly compelled to eat sentient flesh. Perhaps the wendigo is a variant or perhaps the ghouls & ghasts are part of a disease and the other a curse?
These guys are A#1 Corpse Eaters, often reside in graveyards. Think of them like the lotus eaters, but beyond redemption and permanently altered.
They do eat their victims, alive or dead, but a living victim who escapes has a chance of contracting the magical disease, just like with vampires. These things don't breed easily because their victims need to escape and they might be why some campaign cultures react strongly against cannibalism, if these monsters reside in noticeable numbers in the area.
"In either case, a ghoul is not the person it was in life. It retains no class levels, and it has nothing more than the barest memories of its previous existence." Spot on for me.
Vampires - D&D vampires were almost entirely mythological and from horror movies, not the vampires we see now since White Wolf and Anne Rice.
Vampires have numerous and powerful benefits as well as drawbacks. In this, ironically, they are similar to paladins. They are both quite limited in the scope of their action, but are highly powerful when operating on "home turf" so to speak.
One similar element is vampires travel in packs, but really, these are a single vampire and its spawn, thrall, which it controls at will when in their presence. That's not like anything around today.
Vampire Spawn are any victims who are buried. That's the key element. They are tied to the soil and if a victim who is drained of blood is burned alive, say, or laid to rest upon a stone altar then they do not become vampires. Only after they are buried, immersed in soil, does the 24 hour transformation occur into a vampire.
By the stats of the MM:
Vampires are rare, hard to hit, move as the humanoid they were in life, can fly 18" (9 squares 3.x) in giant bat form, are very tough in HP, are only 25% at home in their lair where a coffin or receptacle lies full of their burial soil, acquire quite a treasure hoard, increase to Exceptional physical and mental ability scores, including intelligence, do normal attack damage with a clawed hand for their size, Drain 2 levels / successful attack, require +1 or better weapons (i.e. magical) to be hit, become Chaotic Evil, gain immunity to Sleep, charm, and hold spells cast on them.
Their restrictions include: Resting in a their soil container during sunlight hours unless below ground. This is when their power is restored, from the soil, not the blood they hunger for. Like all undead (key words here), they exist in two planes at once, the material and the negative energy plane which powers their unlife. They have an aversion effect to garlic, mirrors, and LG (lawful and/or good) holy symbols. This is not a fear effect, rather they might plug their nose or avert their eyes before continuing to attack. Sunlight exposure kills them in 10 minutes & turns them powerless immediately (I guess like Superman's kryptonite). (Total) Immersion in running water can destroy them, dealing 1/3 hp loss per round. A wooden stake through the heart stops them cold, but they reanimate, if it is ever removed. to finish the job the beast's head must be severed and it's mouth stuffed with holy wafers (or it presumably regenerates and possibly even seeks its head). Lastly Holy Water is treated like an acid in terms of damage to a vampire.
More benefits - cause they just don't get enough.
STR: 18/76
Regeneration 3/rd
gaseous form and return to coffin in 12 rds, rest 8 hrs, then reincorporates
Immune to poison & Paralysis
1/2 damage from electrical and cold damage
Assume gaseous form at will or that of a large bat
Charm [Person?] gaze with -2 penalty on Saving Throw for victim
Summon 10d10 rats or bats when underground, 3d6 wolves in wilds. These arrive in 2d6 rounds
New vampires are created when one {"drains all the life energy" of a human or humanoid. Class levels are retained. Spawn only become free-willed monsters, if their sire is killed (but I could see intelligent spawn having more leeway in their actions)
Eastern Vampires are invisible, but have no charm gaze or gaseous form at will. Given early D&D's record with "Oriental Adventures" I think we could do better emulating other culture's myths and legends, so the alternate vampire types by region might be better researched.[/sblock]