Enemies

Training:
* Training Dummy (Level 0)
* Melee Dummy (Levels 3-7)
* Gun Dummy (Levels 6-14)
* Flying Dummy (Levels 7-19)

Undead:
* Babycrab (Levels 1-7)
* Headcrab (Levels 3-12)
* Zombie (Levels 2-20)
* Zombie Torso (Levels 4-18)
* Ice Crab (Levels 10-25)
* Ice Zombie (Levels 9-30)
* Ice Zombie Torso (Levels 8-27)
* Fire Crab (Levels 10-25)
* Fire Zombie (Levels 9-30)
* Fire Zombie Torso (Levels 8-27)
* Zombine (Levels 30-55)
* Fast Headcrab (Levels 15-40)
* Black Headcrab (Levels 12-33)
* Poison Headcrab (Levels 30-65, inflicts poison)
* Elite Zombine (Levels 45-70)
* Fast Zombie (Levels 40-65)
* Fast Zombie Torso (Levels 38-60)
* Poison Zombie (Levels 50-75, throws poison headcrabs)
* Gonome (Levels 60-80, inflicts poison)
* Gonarch (Levels 105-110)

Xenian Wildlife:
* Barnacle (Levels 1-30)
* Chumtoad (Levels 10-25)
* Archer (Levels 15-40)
* Stukabat (Levels 5-30)
* Bullsquid (Levels 7-42)
* Houndeye (Levels 9-51)
* Blue Panther Eye (Levels 17-38)
* Red Panther Eye (Levels 29-46)
* Kingpin (Levels 17-34, inflicts poison)
* Mr. Friendly (Levels 15-39, inflicts stop for 5 seconds)
* Snark (Levels 1-20)
* Tentacle (Levels 30-90)
* Boid (Levels 20-60)

Antlions:
* Antlion Grub (Levels 1-5, inflicts stop for 10 seconds)
* Forest Antlion (Levels 5-40)
* Beach Antlion (Levels 10-55)
* Desert Antlion (Levels 15-65)
* Antlion Worker (Levels 30-70)
* Antlion Guard (Levels 65-95)
* Antlion Guardian (Levels 90-110)

The Combine:
* Metro Cop - Stunstick (Levels 20-45)
* Metro Cop - Pistol (Levels 15-40)
* Metro Cop - SMG (Levels 30-60)
* Metro Cop - Magnum (Levels 55-80)
* Metro Cop - Shotgun (Levels 50-75)
* Metro Cop Elite (Levels 60-90)
* Combine Soldier - SMG (Levels 35-65)
* Combine Soldier - AR2 (Levels 40-75)
* Combine Shotgunner (Levels 55-80)
* Combine Soldier - OICW (Levels 30-60)
* Combine Guard - SMG (Levels 35-65)
* Combine Guard - AR2 (Levels 40-75)
* Combine Guard - OICW (Levels 30-60)
* Shotgunner Guard (Levels 55-80)
* Combine Elite (Levels 60-90)
* Stalker - Yellow Beam (Levels 20-50)
* Stalker - Red Beam (Levels 40-70)
* Combine Dropship - Containor (Levels 60-90)
* Combine Dropship - Strider (Levels 80-105)
* Combine Gunship (Levels 100-130)
* Strider (Levels 120-175)
* Crabsynth (Levels 70-100)
* Mortarsynth (Levels 40-85)
* Hunter (Levels 70-110)
* Combine Advisor Pod (Levels 150-155)
* Combine Advisor (Levels 180-200)
* Little Thumper (Levels 25-35)
* Big Thumper (Levels 40-60)
* Combine Turret (Levels 30-65)
* Ceiling Turret (Levels 55-80)
* Ground Turret (Levels 55-80)
* City Scanner (Levels 5-60, inflicts blind)
* Shield Scanner (Levels 15-25, inflicts blind)
* Laser Scanner (Levels 35-60, inflicts blind)
* Wasteland Scanner (Levels 40-70, inflicts blind)
* Combine Security Camera (Levels 10-15, inflicts blind)
* Manhack (Levels 20-75)
* Hopper Mine (Levels 15-80)
* Rollermine (Levels 40-85)
* Combine APC (Levels 80-135)
* Hunter-Chopper (Levels 90-140)

Race X:
* Pit Drone (Levels 50-75)
* Shock Roach (Levels 15-35)
* Shock Trooper (Levels 55-90)
* Baby Voltigore (Levels 40-70)
* Voltigore (Levels 90-140)
* Parasite (Levels 60-100)
* Pit Worm (Level 150)
* Gene Worm (Level 180)

Underwater:
* Ichthyosaur (Levels 35-75) - Xenian Wildlife
* Leech (No Level, not killable) - Xenian Wildlife
* Underwater Scanner (Levels 25-55)
* Combine Submarine (Levels 80-135)