|This article is about the current version of DF.|
A corpse has several levels of decay. It will begin as "(creature or name) corpse", progress to "rotten (creature or name) corpse", "(creature or name) partially decayed corpse", and finally to "(creature or name) skeleton", and will remain at the final level indefinitely. If the creature had had parts ripped or cut off before death, the corpse will be described as "mutilated corpse" and "partial skeleton" in the respective descriptions, and the parts (if still on the map) will decay into a type of bone depending on the part. A creature with parts that were destroyed (i.e. exploded into gore, cloven asunder, torn into shreds, etc.) before death will be described as a "mangled corpse".
Letting corpses naturally rot is the only way to get usable bones from creatures that dwarves refuse to butcher (such as goblins, elves, and other sentient creatures), according to their ethics (unless you modded the ethics). Cutting a live goblin up using serrated blade traps or throwing them down extreme heights (such that they explode) will generate usable goblin bones and skulls. Already-dead corpses can be reanimated with the help of a necromancer, or naturally if you are in any type of evil embark, and then dissected. Remains of vermin, however, simply progress from "(vermin) remains" to "rotten (vermin) remains" before simply vanishing.
Butchering a corpse produces quantities of meat, prepared organs, bones, a skull, skin, and nails/hoofs, as well as cartilage, nervous tissue, and other byproducts. Body parts can be butchered, presumably for whatever tissues/organs were in the part. "Butchering" a skeleton produces only a skull, bones, cartilage and other non-decaying tissues. The corpses of very small animals, such as of ravens, currently cannot be butchered. Also, corpses of tamed (not stray) animals can't be butchered. Being "mangled" does not affect a corpse's ability to be butchered.
Rotting corpses will produce miasma in subterranean areas, but not above ground.
If the corpse of a dwarf is left unburied, it will cause unhappy thoughts in the surviving family and friends. The soul of a dwarf that has not been properly put to rest may return for vengeance, which can lead to even more Fun.
Animal trainers will also receive negative thoughts if an animal they bonded with is allowed to rot. If they bond with an animal who is not a pet and who dies in any manner aside from butchering, it is advisable to quickly atom smash the corpse as there is no other way of actually preventing it from rotting.
Seeing body parts and corpses of sapient creatures, in general, can cause dwarves with insufficient discipline to become horrified, leading them to cancel their current task and run away. A caravan that sees corpses may decide to not trade.
Improperly stored corpses can be a great source of FUN in the event a necromancer enters combat. (protip: NEVER assign a necromancer the hunting labor.)
Corpses can be raised from the dead – this will occur in some evil biomes, if the creature is killed inside an evil biome. On an embark location between an evil and a non-evil biome, corpses killed on the non-evil side will not rise. Corpses may also be raised by a necromancer into a slave, or resurrect themselves as mummies and themselves gain the power to raise corpses, though mummies will normally only be encountered in tombs in adventure mode. Mangled corpses with pulped heads or upper bodies will never become undead. Severed body parts will be able to rise if they have either a [GRASP] tag (hands and possibly other body parts) or if they still have a head attached, so it may be advisable to kill risen corpses with blunt weaponry to avoid swarms of body parts and to permanently pulp them to death. Corpses and severed body parts will not rise again if they have been butchered, their skin tanned and their hair spun into thread, or if they have been exposed to magma. The zombies themselves will also be destroyed by magma.