There are three monster types in Diablo II: demons, undead and animals. A monster can only belong to one of these groups. Demons and undead are exactly what they sound like, and animals are all the other monsters that are neither demons nor undead. These monsters do not have to look anything like animals at all, an example being the Zealots of act III, which are in fact just humans.
Animal is not a game term strictly speaking, but rather a term used on Arreat Summit to differentiate between monster types. While constructs like Gargoyle Traps are not listed as animals there, they will be listed as animals here simply because they are not demons or undead, and it makes little sense to split them up since they function exactly like all other monsters classified as animals from a game mechanics perspective.
Total Monsters:
- Animals: 36
- Demons: 23
- Undead: 13
What It Means[]
If a monster is an animal, no specific gameplay mechanics apply to it. If a monster is a demon or undead however, there are some special effects to take into account.
Demons and undead both take additional damage from weapons with the "extra damage to demons/undead" modifier and are more easily hit by weapons with "attack rating against demons and undead" modifiers.
In addition, there are several Paladin skills that affect undead and demons only.
Animals[]
| Monster | Act I | Act II | Act III | Act IV | Act V | Act V Guest |
| Blood Hawk | x | x | x | x | ||
| Blood Hawk Nest | x | x | ||||
| Flying Scimitar | x | x | ||||
| Gargoyle Trap | x | |||||
| Giant Spider | x | x | x | |||
| Spike Fiend | x | x | ||||
| Wendigo | x | x | x | |||
| Baboon Demon | x | x | x | |||
| Bat Demon | x | x | x | x | ||
| Claw Viper | x | x | x | |||
| Fire Tower | x | |||||
| Leaper | x | x | x | x | ||
| Lightning Spire | x | |||||
| Mummy Sarcophagus | x | |||||
| Sabre Cat | x | x | ||||
| Sand Maggot | x | x | x | x | ||
| Sand Maggot Egg | x | x | x | x | ||
| Sand Maggot Young | x | x | x | x | ||
| Sand Raider | x | x | x | |||
| Scarab Demon | x | x | x | |||
| Slinger | x | x | ||||
| Swarm | x | x | ||||
| Frog Demon | x | |||||
| Giant Mosquito | x | |||||
| Tentacle Beast | x | |||||
| Thorned Hulk | x | x | ||||
| Zakarum Zealot | x | x | ||||
| Zakarum Priest | x | x | ||||
| Abominable | x | |||||
| Baal's Minion | x | |||||
| Blood Lord | x | |||||
| Catapult | x | |||||
| Frozen Horror | x | |||||
| Death Mauler | x | |||||
| Suicide Minion | x | |||||
| Siege Beast | x | |||||
| Total | 7 | 19 | 16 | 5 | 8 | 17 |
Demons[]
| Monster | Act I | Act II | Act III | Act IV | Act V | Act V Guest |
| Corrupt Rogue | x | x | x | |||
| Corrupt Rogue Archer | x | x | x | |||
| Corrupt Rogue Spearwoman | x | x | ||||
| Fallen | x | x | x | |||
| Fallen Shaman | x | x | x | |||
| Fetish | x | x | x | |||
| Goatman | x | x | x | |||
| Tainted | x | x | x | |||
| Blunderbore | x | x | x | x | ||
| Vulture Demon | x | x | x | |||
| Council Member | x | x | ||||
| Fetish Shaman | x | x | ||||
| Megademon | x | x | ||||
| Regurgitator | x | x | ||||
| Vile Child | x | x | ||||
| Vile Mother | x | x | ||||
| Demon Imp | x | |||||
| Minion of Destruction | x | |||||
| Overseer | x | |||||
| Pain Worm | x | |||||
| Putrid Defiler | x | |||||
| Stygian Fury | x | |||||
| Succubus | x | |||||
| Total | 8 | 3 | 7 | 6 | 10 | 15 |
Undead[]
| Monster | Act I | Act II | Act III | Act IV | Act V | Act V Guest |
| Skeleton | x | x | x | x | ||
| Skeleton Archer | x | x | x | |||
| Skeleton Mage | x | x | x | |||
| Vampire | x | x | x | x | ||
| Wraith | x | x | x | x | ||
| Zombie | x | x | x | |||
| Mummy | x | x | x | |||
| Greater Mummy | x | x | x | |||
| Willowisp | x | x | x | |||
| Bone Fetish | x | x | ||||
| Finger Mage | x | x | ||||
| Oblivion Knight | x | x | ||||
| Reanimated Horde | x | |||||
| Total | 6 | 8 | 8 | 3 | 1 | 11 |