A thousand years of death's carnage gathered 'fore the morn,
Their vengeance turned against mankind's unsuspecting head
There's no defense, there's no escape, you cannot kill the dead!"
Come in several varieties.
- Death, a.k.a. The Grim Reaper: The big guy himself, usually portrayed as an Implacable Man in a Black Cloak carrying a Sinister Scythe. But not always. MAY SPEAK IN ALL CAPS. Is a very diligent worker, who truly deserves some vacation time every now and then. He might ask you nicely to Go into the Light or he might try to send you there himself. Or he might just be a cool guy that fancies himself a nice game of chess. There are also variations that look similar to The Grim Reaper but aren't unique beings, yet still more dangerous and rare than your run-of-the-mill skeleton. He and his lesser servants may be formerly human, especially if You Kill It, You Bought It is in effect; other times they will just be Anthropomorphic Personifications of Death who have a lot in common with the Undead even though they aren't dead humans.
- Death Knights: What liches are to sorcerers, these guys are to warriors. They rarely appear unless the undead are an organized army, and when they do, they function either as its generals, shock troopers, or both. They are nearly always found on horseback (either skeletal or pitch black), their weapon of choice often is a one-handed bastard sword with a skull on the hilt, and their armor is richly decorated with skulls, bones, distorted faces, and other heraldry related to death. Their actual appearance varies between a pale human, a skeleton, and completely spectral, relying on a possessed suit of armor instead. Popularized by Lord Soth of Dragonlance, though the Ur-Example are probably the Nazgûl from The Lord of the Rings.
- Flesh Golem: When a thrifty necromancer or mad scientist has a large number of spare parts left over from constructing their undead legions, you get a flesh golem. Similar to the previous in that these are a reanimated assembly of body parts, flesh golems tend to represent a more... whimsical approach to anatomy. Parts need not be assembled in a humanoid form — or in a logical way for that matter — and they may not even all be from the same species. Designs tend to be rather freeform and range from haphazardly fused clumps of bodies, to lumbering Multi-Armed and Dangerous humanoids, to animalistic tangles of limbs.
- Frankenstein's Monster: Or anything else made from human corpses and brought back with technology. The original was big, a quick learner, and very, very pissed at his creator. The modern type is a bit more pitiable. Usually the stitches show, so you can tell them apart from zombies. The intelligence level varies. They seem to have universal Super Strength, so don't challenge one to arm wrestling. Also note that, depending on the work, these may not be "technically" undead, and hence not vulnerable to holy power and tricks like the Trope Namer of Revive Kills Zombie.
- Ghosts: Walking corpses without the corpses, most are understandably ticked off about this. Other than that, they have little in common, varying nearly as much as the rest of the undead put together. Depending on the genre, they can be anything from harmless pranksters to Lovecraftian horrors; you'll know which one yours is once he starts smearing things on the wall. If it's crayon, you're generally okay; if it's blood, you are so horribly screwed it's not even funny. Unless you realize that you're already one of them... but hey, most people who run into them know who they're gonna call. Unlike most forms of undeath, ghosts can be friendly. They may return to protect a loved one, or reward someone who arranged their burial, or the like. Ghosts also come in many flavors. In a lot of works, various words for ghost, such as phantom, spectre, wraith, etc. usually mean different varieties of ghost.
- Ghouls: Originally deriving from Arabic folklore, but popularized by H.P. Lovecraft's stories and subsequent media, their depiction varies from animated corpses to living beings, but when undead, they usually are depicted as bestial and hyper-aggressive zombies. Intelligence and appearance vary; in the original folktales, these creatures could sometimes be mistaken for (and marry) humans, but recent interpretations have made them animalistic in behavior and more obviously corpselike in aspect. Unlike zombies, they generally retain some degree of free will. Some variations of ghouls tend to feast exclusively on the dead, but that only means they have to kill someone before they eat them.
- Liches: Popularized in Dungeons & Dragons and common in modern Fantasy, a lich is an Evil Sorcerer who retains his or her magical powers after death — basically a revenant with a little something extra. The lich becomes undead by placing its soul in a Soul Jar (or maybe seven of them), and can only be permanently destroyed by destroying said Soul Jar; in other fictions, the Soul Jar is optional. A lich's physical appearance can range from near-normal to zombie-like to completely skeletal, which usually depends on the lich's age. Because of their skill at magic, especially necromancy, liches tend to be among the most powerful and dangerous type of undead (if not the most powerful and dangerous) in settings where they exist. In the hierarchy of The Necrocracy, they are guaranteed to be the top tier.
- Mummies: The mummy shambles towards the archaeologists who have defiled its tomb. Luckily for them, it doesn't move fast due to sleeping for three thousand years (although there are exceptions). The classical depiction is wrapped in white bandages, and no one wants to see what's underneath them. Sometimes they can be easily defeated by simply pulling off their bandages, but if they possess magical abilities, then it is unlikely that this tactic will be of any effect. In those cases you can count on them to be about as mighty as the Liches. However, mummies tend to be especially vulnerable to fire.
- Revenants: Your standard resuscitated corpse; however, unlike a zombie, this undead isn't quite so rotting and falling apart, fairly intelligent, and, most importantly, an individual, since they retain their memories from their previous lives. They tend to seek vengeance for past wrongs, especially if they were murdered. While conceptually very old, and the prototype from which many other undead derive, this trope has fallen out of favor for the horde of zombies and the bloodsucking vampire. Often Living on Borrowed Time.
- Skeletons: Zombies without meat, so to speak. Tend to be difficult to hurt because they are all bone, so blunt weapons (or magic, if available) are required or at least useful. Other versions are simply cannon fodder undead. Most of them aren't particularly smart (not having a brain and all). Only really common in out-and-out fantasy, as they're a little too fantastic for sci-fi or horror; expect them to be magically reanimated soldiers for the Evil Sorcerer or Vain Sorceress that don't need to eat or sleep, and stand guard over tombs for centuries if need be. Despite being fleshless, The Dead Have Eyes.
- Calacas: Particularly common in Latin American inspired content/worlds are the much more expressive Calacas. They aren't typical 'horror' creatures despite being dead. They live loud and colorful afterlives.
- Undead Children: Take one of the above kinds of undead, but make it a Fetus or Enfant Terrible. Now they're twice as creepy and hard to shoot at.
- Vampires: Like zombies, only faster, stronger, and smarter. They suck blood, and may spend a lot of time angsting about it. Usually highly attractive, and both genders tend to be somewhat... festive. Dislike holy stuff, bright light, and pointy sticks. Originally they were not attractive, at allnote , and they also tended to have ruddy complexions (from all the blood) rather than pale ones.
- Werewolves: They are occasionally considered undead in older myths, but generally, modern werewolves are not undead, being people who survive a werewolf attack, as those who die usually do not return as werewolves. Sometimes they're just lumped in the same category of "creepy things", regardless of the level of truth to it. To quote one Ankh-Morporkian: "They're big and scary, come from Überwald, and don't die when you stick a sword in them. What more do you want?"
- Wights: More or less the mummy's northerly cousin, associated with Medieval European Fantasy. Tolkien popularized them as wights note and established the modern interpretation, but they appear in Norse Oral tradition note . The first written appearances are Older Than Print, but these are only the first formal recordings of an oral tradition Older Than Dirt, probably a part of European folklore since the first kid dared another kid to spend the night next to a burial mound. The wight is an old, buried, usually desiccated or naturally mummified corpsenote that rises up to guard its tomb or place of death from intruders. More eldritch and drier than a zombie, but fresher and much less powerful than a lich.
- Popularized by The Elder Scrolls series, but again, dating back to Norse Oral tradition, the Draugr is a related variety of undead. These, essentially, are the wights of particularly greedy, evil, or stong-willed individuals who manage to retain a greater amount of mental and physical ability. They are not bound to their grave or site of death, though many choose to use such places as a lair out of entitlement or convenience. They possess great magical abilities, including the power to raise their victims as wights. These are the prototype for the Lich and reflect certain aspects of the Revenant and Vampire of nearby cultures.
- Zombies: Just ordinary, run-of-the-mill walking corpses. They come in a variety of types, but they tend to share some general traits. Zombies tend to be Slow (usually...), weak (comparatively...), mostly blind (unless they aren't), and stupid (at first...). Surprisingly squishy, but they don't really notice. Made with Hollywood Voodoo in older works (where they are often seen more as a toiling victim rather than a threat), and The Virus in newer ones. Don't get bitten by the latter form. Some of them die quickly when burned. Others... don't. The voodoo version can sometimes be released from their condition simply by dosing them with salt. However, most, if not all zombies, can be quickly taken down by Removing the Head or Destroying the Brain... except when they aren't. The Parasite Zombie can be highly resilient and adaptable and mutate its host in exotic ways. Know the characteristics of your local zombies to avoid embarrassing mistakes!
- Non-Human Undead: Not all undead begin as humans. A work that includes the undead often includes other fantastical or otherworldly creatures, and these may be just as likely to get up and walk around when they're supposed to be dead. Such entities may also be any of the above types of undead in addition to this trope.
One way undead vary is the nature of their mind and soul. In some cases, including liches, most ghosts, and some vampires, they keep their original soul. They can still remember the simple pleasures of life, but they can no longer experience them, a frustration which may fill them with hatred of the living, or simply make their existence an unliving hell. Sympathetic undead are most often from this category.
In other cases, including many traditional vampires and some zombies, the undead are actually animated by evil spirits or demons. They may have access to the memory of the person whose corpse they are wearing, but they are not truly the deceased. These types are almost invariably evil, and are much more likely to be vulnerable to religious symbols and rituals.
The remaining undead may be little more than puppets of a necromancer, or they may be powered by magic alone, but they have no animating spirit (at least, not a sentient one).
See also Night of the Living Mooks, Big Boo's Haunt, Clown-Car Grave, Animate Dead. Frequently, they find out Undeath Always Ends. But The Dead Can Dance! Heroes often find that Removing the Head or Destroying the Brain is the only way to kill them.
The Undead Index collects more of the related tropes.