Basic Information
Exactly as it says on the tin, this is an undead creature consisting of the animate skeleton of something - normally a human. Human skeletons would seem to be the default since they have the widest range of uses, but big things with pointy teeth are also popular and the category of 'skeleton' is sometimes extended to cover fossils as well under the Rule of Cool. Small, annoying skeletons tend to be either a sign of someone even less rational than the usual run of those who like re-animating dead things, something so hellacious powerful that it can afford to waste that kind of effort or something so blind and/or indiscriminate that it is raising the dead promiscuously. Or it could be all three at once…
Skeletons can probably be reckoned to beat other forms of 'entry level' undead on being better company (since they've finished rotting) and frequently quicker on what's left of their feet. Against that they're often not as strong and, if you like your reality congruent, should probably cost more magic to animate since it also has to hold the thing together. How hard they are to destroy will depend on the setting - in some they are easily broken, in others they can self-reassemble and require viguorous beating to put them down. Expect your slashing weapons to be relatively ineffective and your piercing weapons - especially guns - to be no help at all.
They are usually vulnerable to "holy" effects, and therefore make a good solo spot for The Cleric but resistant to many forms of magic1, as well as poisons, heat, cold, disease and other things that rely on the target having fleshy bits to meddle with.
Where they come from2 varies - sometimes you require "divine"/infernal/spiritual assistance, sometimes (black) magic and sometimes either and in some settings they don't even qualify as undead and are simply magical constructs built from unethical materials. Again, dependant on the setting, they may need to be carefully assembled before animation or may simply fly together from a pile of bones. The difference may lie in the power of the creator. Unlike many undead they usually don't "spawn" from their victims, although they may strip the dead for spares.
The self assembly type would seem much easier to store until needed if anyone cares about that.
"Historical" roots can be found in all sorts of places - animate skeletons appear quite a lot in medieval European art, frequently in Dances of Death or momento mori, but these may be figurative and it's not clear that our ancestors considered them a real or potential hazard. The Amerindian peoples, on the other hand, seem to have regarded skeletal undead as a distinct possibility - not least because they were prone to skeletonising their dead before burial. Such skeletal undead were not always malevolent - several legends have them simply dropping in to visit the living out of boredom - but they could also appear due to failure to properly maintain their graves and respect their memory - or even incautious repetition of their names.
Sources
Movie: Jason and the Argonauts (1963) — includes THE classic scene of skeletal warriors attacking animated by Ray Harryhausen.
Game and Story Use
- Self assembly skeletons make a useful load for a trap.
- They could also be a good infiltration strategy, smuggled into a castle or town in consignments of other goods and activated en masse to take the place from within.
- Start this in media res as the PCs find skeletons on the rampage everywhere and have to a) survive, b) save everyone else and c) find out what the hell happened.
- Let them forestall it part way through, perhaps because someone nosey opened one of the boxes and turned up dead.
- Even on a smaller scale, one beserk skeleton leaping out of a box could be a nuisance in the right place:
- As a surprise guard on a chest.
- As an assasination tool, delivered to someone in a crate of something else.
- As an unexpected bonus in a crate of black market goods, embezzled from a larger smuggling operation by an ignorant mook who has sold it as a crate of (whatever the skeleton is hidden in).
- A more "industrialised" fantasy world might sell skeletons retail.
- More traditionally they make good "entry level" undead and/or mooks.
- Use 'trivial' skeletons as mentioned above as set dressing for a bad place.
- Hope that no-one capable of spawning the "self-assembly" kind gets access to an ossuary - although this could make for a climatic moment as hundreds of skeletons come pouring out of it, or a race against time as PCs hurry to interrupt the raising ritual.
- Like the fantasy zombie these critters need to be checked for ontological inertia - if destroying their creator does de-animate them, this will lead to a very different world than one in which they merely become uncontrolled "roamers". The first allows high-fantasy heroics in which a huge swathe of the enemy army suddenly crumbles to dust at a climactic moment, the second the sort of world in which low level adventurers can meet and defeat a small numbers of aimless undead in starter dungeons.
- Why Was Benjamin Franklins Basement Filled With Skeletons?