Monsters, Creatures

Looter > collects things off of dead/ steal items from character
Scavenger > loots things from dead bodies (Pack of Hyenas)
Siren > Song that can Possess you (make you run away you loose control) or stun you
Succubus >
Manticore > scorpion tail can stun
Tendrill > slow but can "elongate" to attack you
Centaur (Centaur Chieftain) > charge attack
Wyvern > different variants (fire, ice) shoot ranged
Gargoyle > lies in wait, ambushes you
HellHound > attack in packs (where there is one there are more) make noise to know of their presence
Gorgon > turns you to stone
VineLurker > vine appendages emanate from the creature that and constrict you, you can "beat a path through" to the center OR hit the eye/center with Ranged attacks)
Creeper > looks like poison plant, but moves area of effect spore attack
Mimic > can disguise itself as Chest, Powerful monster i.e. Dragon, etc.)
SpineHound/HedgeHound
Dark Harvester > revives/resurrects any beast (or human) to turn it against you
Yeti
Gore-beast Horned (like a rhino charges and gores you)
Dervish/Typhoon
Musk/Mist
Drake
Wisp
TendrilHulk
Gloom--
--Guardian
Kraken
Lizard Man
Corpse
Golem
Stalker
Shambler
Lich
Omen
Horror
Jelly > if attacked and not killed splits in 2 with 50% HP each
-Mole
-Rot Rotten-
Sprite
Pixie
Wraith
Necro-
Phantom/Poltergeist
Needle-
Revenant
Putrid -
Urchin
Wither
-Fiend- (Bone Fiend)
-Vermin
Wasp
Scorpion
MantaWraith (Shock/Lightning)
Python/Serpent
Gremlin
Squid
Balrog
Spider/Arachnid
SerpentMan
Parasites (attach on you and hard to remove...Burn of Poison off)
Leech (Variants)
Mite (Variants)

Creature Variations (Extremes)
Small Enemies   Giant Enemies
Magical      Physical

Stealthy    - Luminescent

Texture (Furry - Spiny - Armored->Slimy-> Thorny ->smooth->scaly ->gas->liquid)

(Slow lumbering -> Quick Agile)

(Tiny -> gigantic)

Aggressive -> Passive->Peaceful->Friendly (Familiar)

Parasitic (Mites, Ticks, Leaches) Symbiotic (Faeries, Sprites, Familiars)

Natural(Vines) Unnatural(Undead) SuperNatural (Wisp)

Solitary(Phantom) Pack Creatures(HellHound)

Flying (Harpy/Succubus) Underground Enemies (BurrowBeast)

Types of Damage:
Piercing/Gouging (through armor armor absorbs a minimal amount of damage... the armor's durability is damaged)
Bashing (armor absorbs some percentage but takes durability damage)
Constricting (attack damage is lessened/interrupted more often, immobile)
Ripping/Tearing/Slashing (on flesh causes bleeding)
Interrupts (if in middle of attack your attack is interrupted)

Example ways in which creatures attack you (their weapons)
Tail (whipping/bashing)
Tongue (whipping, constricting)
Spit/Vomit (ranged)
Melee (Normal Weapons Swords/Clubs/Flails)
Spines (shooting)
Jaws/Teeth (Biting can transmit disease and cause bleed damage)
Thorns (ThornHulk uses thorn branches to attack)
Acid/Venom (on fangs or shot does physical damage or damage to weapons/armor)
Claws/Pinchers/Talons  (physical damage, slashing bleeding damage)
Stinger (bees/scorpions do stun damage, slow)
Horn (gouge damage, charge damage)
Elemental (fire, ice, shock)
Shock Damage has more effect if you are in water
Fire Damage has less effect if you are in water
Breath (elemental usually, also knockback and modifies environment (lights on fire or ice obstructions)
Spores (confuse, debuff, poison, slow) confuse can effect how you move (disorient you)
Noise (Sirens can charm/confuse/possess you or call in reenforcements to fight you, Roars can cause FEAR (vibration))
Light/Darkness (Enemies can "blind" you or "flashbang" stun you)
Web/Tar (Sticky stuff to limit your mobility and slow attacks/speed)
Ink (i.e. from a Squid - > blind)
Smoke (obstructs vision/blinds)
Gas
Magical Attacks (possess, curse,)
Constriction/Crushing (Python)
Undead (they should be described more discretely... undead 10th Legionaire, Gladiator Barbarian)

Defense mechanisms
Immunities (i.e. immune to fire, poison, dark magic, armor classes)
Some Enemies Reflect attacks (Monk particularly good at deflecting/reflecting physical attacks, Cleric Reflects spells)
Some Enemies are Healed by attacks (Spectres are healed and energized by some magic)
Play Dead
Cloak
Decoy (spiritual)
Spells Push
Spell Regen/Heal
Disarm
Explosive
Summon
Burrow (dig away)
Tangle (web, vines)
Curl up into ball (Defense, Turtle)
Smoke/Ink to evade and escape
Spines (if you hit them you take damage)
Spores/Gas(confuse or interrupt release if they are attacked)
Tar (slows you down)
Poison/Disease