Forces

Resistance Infantry:
* Citizen
* Refugee
* Rebel
* Medic
* Engineer
* Rebel ODST
* Stealth Rebel
* Shield Rebel

Combine Infantry:
* Metro Cop
* Elite Metrocop
* Combine Soldier
* Combine Shotgunner
* Combine Guard
* Shotgunner Guard
* Combine Assassin
* Combine Elite
* Stealth Soldier
* Shield Soldier
* Stalker

Xenian Infantry:
* Vortigaunt
* Xenian Grunt
* Controller
* Gargantua
* Baby Gargantua

Xenian Wildlife:
* Houndeye
* Bullsquid
* Barnacle
* Antlion
* Antlion Grub
* Antlion Worker
* Antlion Guard
* Antlion Guardian
* Tentacle

Infection / Undead:
* Headcrab
* Fast Headcrab (sometimes explosives are planted on them)
* Poison Headcrab
* Baby Headcrab
* Zombie (Models: Normal, Citizen, Rebel, ODST, Stealth, Shield)
* Zombie Torso (Models: Same as Zombie)
* Zombine (Models: Normal, Shotgunner, Elite, Assassin, Stealth, Guard, Shotgunner Guard)
* Zombine Torso (Models: Same as Zombine)
* Fast Zombie (Models: Normal, Stealth, Shield)
* Poison Zombie (Models: Normal, Stealth)
* Gonome
* Gonarch

Race X:
* Pit Drone
* Shock Trooper
* Voltigore
* Baby Voltigore
* Parasite
* Pit Worm
* Gene Worm