More posibilities how to kill mobs/players
SFENCE

Add more posibilities how to kill mobs and/or players, like traps, throwable TNT, etc.

Traders
Sokomine

Configurable mobs/NPC which can trade for you.

Visual Harm 1Ndicators
Mantar

HP bars for mobs/players

3D Armor Mobile
LandarVargan

Adds a command to bring up a formspec that allows mobile users to put on armor

Large Slugs
jwmhjwmh

Adds node-based slug mobs to your world

Alive AI
AiTechEye

Advanced survivor ai mobs (npc, monsters and more)

Moblib
LMD

Low-level high-performance entity library

Mobs NPC
TenPlus1

Adds simple NPC and Trader.

Grave
ElCeejo

Adds an eerie biome with multiple mobs.

Slimes Redo
TenPlus1

Add green and lava slimes to your world.

Invisiblocks
TenPlus1

Add invisible barrier, light and mob wall into game with new tool

mime (flux's fork)
fluxionary

adds a monster mimicking its surrounding nodes.

Sky Mobs
TenPlus1

Sky Mobs for Mobs Redo

Balrog Sword MT 5.4
DragonWrangler

allows those using the old mobs balrog mod to have balrog swords

MFSM Multiple Finite State Machine
Sumi

Allows for multple states to be active, while maintaining typical state machine behavior. Good for gamestate and mobs.

Mesebox
johalun

Mobile storage box powered by Mese

MobConf
zeuner

Place, remove and configure Mobs (for now: NPCs) using chatcommands

Extreme Randomizer
NO11

Randomises crafting, mob and block drops.

Zoonami 3D Mobs
isaiah658

Adds 3D monster mobs to Zoonami.

Mobkit
mt-mods

Entity API

Creatura
ElCeejo

A performant, semi-modular, Animal focused mob API

Living Slimes
EmptyStar

Adds living slime mobs to Minetest

Mob Crab (Beta)
Can202

Adds Crabs.

Mobs Ghost Redo
TenPlus1

Adds ghosts.

Mobs Animal
TenPlus1

Adds farm animals.

Mob Biome Mapper
Neuromancer

Allows mobs to spawn in biomes that don't support them.

Mob Horse
TenPlus1

Adds rideable horse

Spawners
SaKeL

Adds spawners for mobs, dungeons, temples and ores.

Mob Mese Monster Classic
TenPlus1

Adds classic Mese Monster.

Wilhelmines Living Caves Mobs
Liil

adds mobs to the caves of your world

Mob Core
mt-mods

A Mob API meant to expand upon mobkit and bring easy to use features for creating new Mobs.

Wisps
ElCeejo

Adds non-entity mobs called Wisps

balrog (flux's fork)
fluxionary

adds balrogs.

More Danger
Twinsonian

Scaling difficulty multiple games/mob apis. Based on the difficulty mobs will have faster movement speed, more damage and more health.

Banshee
ElCeejo

Adds Banshees, a ghostly mob that haunts pine forests

Tortou
LibraSubtilis

Turtle graphics, hyperloop travelingsystem and cubic mobs.

Raids
DragonWrangler

Allows server owners or server admin to start mob raids to attack settlements or players

Not So Simple Mobs
TenPlus1

Adds a host of creatures into your world with new weapons too.

Mob BiomeDb Mapper
Neuromancer

Allows mobs to spawn in biomes that don't support them (Using info from BiomeDb)

Skeleton
AntumDeluge

A skeleton mob.