Here is a list of all the monsters in brief. Click on their names for further information about them.
SuperUniques
In lack of a name of "boss type" units, we are calling them SuperUniques for now.
"Living siege Engine of Hell". The
Siege Breaker is an absolutely massive "miniboss" shown in the
WWI 2008 gameplay video. It's apparent that Blizzard is taking the gameplay with even the minor bosses to a whole new level in Diablo III! We don't know if he's a random encounter or not, but this big bad-ass is found in
Leoric Highlands.
Inside the
forgotten Tombs of the
WWI 2008 gameplay video, we got familiar with the
Thousand Pounder, a boss with apparent random
monster attributes (
Gluttony &
Incarnate), as he was summoned in to the scene (whether or not these attributes are randomly chosen when a Thousand Pounder is spawn, is unknown). He's also seen in concept art work, and looks more like an overly powerful monster than an actual type of boss, like a SuperUnique.
Standard Monsters
Even the "standard" monsters of Diablo III comes in many different shapes and forms, and employs different types of obstacles for the player.
Scary looking humanoid demonic creation made from willing
Dark Vessels. Activated Vessels are mutated, half-demonic things who fight furiously and move very quickly. It's a good idea to kill off the Dark Vessels before they can activate, if at all possible.
Beasts are large, buffalo-like herd beasts seen in the plains areas of Diablo III. They have a very fast charging attack, and gore with their huge tusks up close, though the few seen in the WWI 2008 gameplay movie died pretty easily. They're not just animals either; they've been mutated by
Diablo (or someone?) to become monstrous.
Berserkers are the muscle of their evil, demon-worshiping cult. They are massive, powerful men who wear hoods and loincloths and carry huge mauls, with which they are happy to bash your brains in.
Berserkers have a special overhead smashing attack, which they telegraph by powering up their mauls with a reddish glow. Their overhead attack is highly damaging, but if you dodge it the Berserker will hit the floor so hard their maul breaks through the stone and gets stuck there.
Crawling Torsos are one of the more disturbing monsters we've yet seen. They are the upper half of a
Walking Corpse, a type of
zombie. If the walking corpse is killed with a powerful hit, it will die completely. If it's only hit with a glancing blow though, it will break in half, and the upper body will become... A crawling torso.
Cultists are human mages who spawn with
Berserkers. Cultists are very weak, but they can shoot fireball projectiles and summon powerful
Dark Demons, so it's wise to bypass the hulking Berserkers to kill the Cultists as quickly as possible.
Cultists can be recognized from
Dark Vessels by their lack of a staff. Vessels have a long staff which curls at the end, on which they lean while summoning up the demons by which they are possessed.
These odd, half-skeletal creatures are summoned from raw, red manhole-like openings in the ground by
Dark Cultists. They are quadrupedal, and look a bit like a dog crossed with a crocodile, then turned inside out. They are quick of foot, but appear to possess only melee attacks.
These human mages are commonly found standing motionless, amidst various other types of Dark enemies. Vessels are harmless in their human form, but become very dangerous
melee fighters if they manage to pull a demonic entity into themselves. In that form they are known as
Activated Vessels, and are ferocious fighters.
Dark Vessels look a bit like
Dark Cultists, but Vessels lean on tall crooks, and remain motionless until they transform, while Cultists are mage-like enemies who cast a variety of spells and summon demons.
Dune Threshers are apparently mostly located north of
Caldeum, which would imply that the game will take us to the surrounding desert areas. They are the croco-sharks of the sand, and is a great threat to anyone wandering in the desert. Well, besides heroes like the average player in
Diablo III. Above two primary front legs these beasts are equipped with a second pair of appendage in the form of gigantic talons that supplement its leap-and-bite attack. The beasts are very fast and most dangerous.
Fallen Shamans return in Diablo III, but none have yet been seen in screenshots. We only know of them thanks to this animated gif, which
Blizzard's D3 Community Manager,
Bashiok, had in his forum signature.
Fallen were in D1 and took on an expanded role with new AI, shamans, and grouping habits in D2 (
Diablo 2 Fallen). How they'll progress in D3 remains to be seen, but everyone seems to like this monster type, so their return is a popular one.
Ghostly Orbs are a sort of monster generator, creating a wraith every few seconds until they are destroyed. They've only been seen in the
WWI 2008 gameplay movie, when four of them emerge from the floor in a trapped room and begin producing wraiths as soon as they are active.
These swarming monsters appear to be the zombie cannon fodder of
Diablo III. They are blue-skinned
undead who spawn in great numbers, are quite fleet of foot and quick of movement, but are fairly weak and easy to kill.
Ghouls can be seen climbing up the walls and swarming the
Barbarian in the beginning of the
WWI 2008 gameplay movie. They die almost as fast as they race to battle (which is quite quickly).
The only type of this monster yet seen is called the
Wood Wraith, but they are called Gnarled Walkers in the concept art, and that seems a more likely name for the entire monster type.
Gnarled Walkers are not just living, Ent-like trees, but are demonic, possessed um... trees. From the concept art they look to be things, mad plants, rather than individual entities. They do not have faces, and they are not bipedal bodies formed from wood. They are literally demonic trees, soulless and mindless and deformed by the dark magics that have animated them.
The
goatmen foot soldiers seen thus far are much as they were in
Diablo II. They mill around in medium-sized packs, wielding huge two-handed polearms, and attack quickly, but not very effectively. The D3 goatmen have quick footspeed and a fast swing, but they pause for a long time between attacks. Their death sounds seem to be improved over how they were in D2, though they're not quite as delightfully bleaty and goaty as they were in D1, when their enticing noises put them amongst everyone's favourite monsters to kill. In Diablo III they finally received a proper
backstory though...
Though
goatmen were a popular monster in D1 and D2, the Goatman Shaman is a new unit, and nothing is yet known about its abilities. Presumably it will be able to buff goatmen in various ways, and perhaps heal or even resurrect them as well. It is known that the shaman have intelligent AI; one in the
WWI 2008 gameplay movie runs when its herd is wiped out by a
Witch Doctor's
Wall of Zombies, finds a new pack of goatmen, and takes up a position behind them.
One of the more interesting monsters seen in the
WWI 2008 movie, the
Grotesque are basically living pinatas. They are fat, white, humanoid monsters, who either don't have an attack or a very weak one. What they do instead is run up to a player who comes into range, take a few hits, bend over backwards, and rupture into a massive fountain of wriggling silver eels called
Lamprey. There seem to be far more eels within a grotesque than their volume would permit, but such is the nature of magic.
Lamprey are squirming eels that emerge in a flood from a ruptured
Grotesque. They are not powerful monsters, but are disgusting in their fecundity and must be stomped out, like giant maggots.
The
scavenger returns from
Diablo I, and it's taken on some properties of the
Leapers from
Diablo II. They look more like animals than demons, and are somewhat badger-like in their furry, striped appearance. But they leap and dart around wildly, and seem quite capable of swarming an unwary hero by sheer numbers.
The basic bones with a bow,
skeleton archers return for their third go 'round in the Diablo series, and they are much as they've ever been. A humanoid skeleton with a bow and a relatively slow firing rate. They are not dangerous one on one, but a pack of them can be pretty nasty, especially against low armor or stationary targets.
Skeletal Shieldmen spawn with large, round, glowing blue shields from which they derive their names. They carry a sword as well, but use it only sporadically, and not with very great effect. Their chief purpose is as a defensive unit, and a phalanx of these skeletons can usually be found in front of
Skeletal Archers or a
Skeletal Summoners. They block very effectively, thwarting most attacks launched straight at them, but are very slow to turn and can be flanked or simply run past without much difficulty.
These skeleton shaman spawn with packs of
Skeletal Archers and
Skeletal Shieldman for protection. The Summoners are larger than regular skeletons, and have glowing purple/pink orbs around their upper bodies. These may be shields, decoration, or an indication what type of elemental damage they deal. During battle the summoners stay to the rear of their foot soldiers, where they keep busy summoning fresh skeletons, or hurling purple projectiles at any players who stray into range.
As iconic as
zombies, animated human
skeletons have been featured in all of the Diablo games, and just about every other fantasy RPG ever made. In D3, plain skeleton warriors are joined
Skeletal Summoners,
Skeletal Archers, and
Skeletal Shieldman, and (perhaps) other types not yet revealed.
These slow moving
zombies are a bit larger than the base model, and can presumably take a bit more punishment. They are a very similar creature though, shambling around aimlessly, too stupid to use weapons or spells, only dangerous in large groups.
Walking corpses have a unique talent, in that upon death they sometimes break in half, but continue the battle as their upper bodies snap off and become a
Crawling Torso.
Wraiths return in
Diablo III, and while their function looks about the same, their graphics have been substantially improved. They were seen emerging from
Ghostly Orbs in the
WWI 2008 movie, and it's not known if they can only come from those odd monster generators, or if they'll be found roaming (floating) freely in the dungeons as well.
Wraiths have a
melee slashing attack, and a ranged life drain attack as well. That one has a lovely graphic, with a swirling stream of blueish vapour flowing from the character to the Wraith.
These
zombies appear to be exclusively female; at least the only ones seen with hover tags are female. The zombie on the right may be a male version, or another zombie subtype that's not yet been seen with a hover name.
If they differ from the other zombies in any way other than their long hair and ripped dresses, it's not yet known.
Zombies return to
Diablo III in much the same form as they occupied in
Diablo I and
Diablo II. Humanoid, slow, shambling, and just generally unpleasant. Their slow speed and negligible intelligence makes them perfect targets for new characters to warm up and level up against.