Corpse

Most enemies leave behind corpses when they die, with the only exceptions among normal enemies being Lost souls, Pain elementals, and all the elite formers (Elite former human, Elite former sergeant, Elite former captain, and Elite former commando). Additionally, Arch-viles and Nightmare arch-viles leave behind a generic "bloody corpse" tile that doesn't count as a corpse for the purposes of respawning or resurrection (it does count for the Blood skulls, Fire skulls, and Hatred skulls though). When it comes to the bosses, most don't leave a corpse when killed, but some do; Bruiser brothers, Shamblers, and Cyberdemons. Bosses that leave behind a corpse can be resurrected just like any other enemy, so be extra sure to destroy their corpses ASAP if playing on Nightmare! difficulty, Angel of Darkness, or are playing Angel of 100 and so are fighting Arch-viles alongside them.

Respawning

On the Nightmare! difficulty level and in Angel of Darkness, corpses will randomly respawn into new enemies as time passes. The newly created enemy is the same kind as the enemy that left the corpse. Enemies will not respawn when their corpse is within the player's vision (though note Arch-viles can still resurrect corpses within your vision), and respawning is permanently prevented if the corpse is destroyed.

Every 10.0s on a level, there is a chance for corpses to respawn. There are two checks for a corpse to respawn: a global check that must be passed if any corpses are to respawn, and then another spawn for each corpse. For the global check, the chance of passing starts at 20% when entering the level and grows by 1% for each subsequent check. The chance of passing the per-corpse checks starts at 10% and increases by 1% for every 100.0s spent on the level.

Respawned enemies give no experience when killed, and will not drop the items in their default inventory, so you will not be able to farm respawns for extra EXP nor ammo. Any other item a respawned enemy picks up however will be dropped upon death, and Vampyre will still absorb HP when killing respawned enemies. Respawned enemies additionally do not count towards the run's kill percentage, so the player does not need to rekill respawned enemies for any badges and medals that require 100% kills or any other kill percentage. Enemies revived by Arch-viles also follow all these rules.

Gibbing

Gibbing a monster prevents it from leaving a corpse and from dropping items. This can be useful if Arch-viles are present (or on Nightmare! difficulty).

To gib a monster you must kill it by dealing a large amount of damage. The amount of damage depends on the maximum health of the monster and the damage type of your weapon. Melee, bullet, shrapnel, and piercing weapons must deal 400% of the monster's maximum health to cause a gib. Plasma and acid weapons must deal 200% of maximum health to gib. Fire weapons are the best at gibbing; they only need to deal 150% of maximum health.

It is also possible to gib corpses after the monster has already died. Corpses that are named after enemies (which excludes the Arch-vile's "bloody corpse"), have 1 HP, and as much armor as the corresponding enemy. Corpses don't block bullets, so you'll usually need explosives to destroy them, which includes your weapons, but also barrels or using other monster's projectiles (in practice, most non-BFG explosiona will destroy all corpses in its radius.) Plasma shotguns (including Plasmatic shrapnel assemblies) and skulls also work, but they are much more rare. Notably, despite being a shotgun with a modified damage type, piercing-damage shotguns do *not* destroy corpses (including the nano Plasma shotgun!).

There are a few other ways to dispose of corpses:

• An enemy killed on a square already containing a corpse will replace the previous corpse with its own. Particularly useful for open areas with no doors, like Hell's Arena.
• An enemy killed on a door will be crushed, and won't leave a corpse.
• An enemy killed in a fluid will sink or dissolve.
• An enemy killed on stairs, or a teleporter, will have its body parts split apart as well.

With the exception of monsters killed in acid or lava, these techniques don't technically "gib" the corpse, thus, they don't prevent it from dropping useful items or ammo.

In a "normal" game, they will only be useful when fighting Arch-viles, but when playing Nightmare, Angel of Darkness or any other level that includes respawning monsters, they will often be invaluable.