A monster class is a group of monsters that can be targeted by a weapon of slaying or armor of immunity.
- Airborne: Vampire Bat, Will-o-the-wisp, Pixie, Phantom, Fury, Ifrit, Phoenix
- Abomination: Bog Monster, Underworm, Kraken, Tentacle Horror
- Animal: Rat, Monkey, Jackal, Eel, Toad, Vampire Bat, Centipede, Spider
- Dar: Dar Blademaster, Dar Battlemage, Dar Priestess
- Dragon: Dragon
- Fireborne: Will-o-the-wisp, Salamander, Flamedancer, Phoenix
- Goblin: Goblin, Goblin Totem, Goblin Conjurer, Goblin Mystic, Goblin Warlord
- Infernal: Flamedancer, Imp, Revenant, Fury, Phantom, Ifrit
- Jelly: Pink Jelly, Acidic Jelly, Black Jelly
- Mage*: Dar Battlemage, Goblin Conjurer, Goblin Mystic, Ogre Shaman, Pixie, Lich
- Ogre: Ogre, Ogre Shaman, Ogre Totem
- Troll: Troll
- Turret: Arrow Turret, Spark Turret, Dart Turret, Flame Turret
- Undead: Zombie, Wraith, Vampire, Phantom, Lich, Revenant
- Waterborne: Eel, Naga, Kraken
These monsters have no monster class: Centaur, Golem, Kobold, Acid Mound, Bloat, Pit Bloat, Explosive Bloat, Warden of Yendor, You, Clone (probably)
*Dar Priestesses are not counted as Mages in the 1.7.5 source code