A monster is an actor controlled by the computer using AI routines present in their DECORATE code. Technically, ZDoom identifies an actor as being a monster by the presence of the ISMONSTER flag, which is part of the Monster combo. Monsters with the COUNTKILL flag are tallied on the intermission screen.
Several effects are monster-specific, including:
- The kill class console command can only be used to kill monsters (e.g., "kill ExplosiveBarrel" will have no effect).
- The kill monsters console command or the "massacre" cheat will kill all currently alive monsters.
- The monster console command will list all currently alive monsters.
- The automap can display monsters with a different color from other things when using a scanner or the map cheat.
- The master/children relationship used by functions such as A_KillMaster only works for monsters.
- Monsters are not spawned when the -nomonster command line parameter or the equivalent DM flag is used.
- Unless changed by the Activation property, monsters activate their special when killed.
- Actors killed by ice damage and without a freeze death use the generic ice death if they are monsters or players (and do not have the NOICEDEATH flag).
- Monsters pained by electric or poison cloud damage will play their HowlSound.