Acid Headcrab: When bit by this Headcrab, your health starts to drain. On death explodes like the Antlion Worker.

Adventure Alyx: Can dodge attacks and has a medkit to heal herself.

Adventure Barney: Can boost his own health to 200 and also has a medkit.

Adventure Monk: When at low health, activates an invincibilty shield for a few seconds. Also has a medkit.

Bomb Barney: Explodes after a while.

Combat G-Man: Has an AR2 and explodes on death.

Combine Antlion Remover: Insta-kills Antlions.

Combine Medic: Heals other soldiers.

Crazy Kleiner: Can tele-frag NPCs, and when low on health turns into metal and regenerates health.

Crazy Mossman: When low on health, regenerates all health once.

Crazy Odessa: Has an RPG.

Creepy Monk: Hivemind. When one gets hurt, all other Creepy Monks go to assist.

Energy Antlion: Disintegrates NPCs.

Exploder Monk: When enemies are in a certain radius, explodes.

Explosive Antlion, Zombie, and Fast Zombie: Explodes on death.

Friendly Breen: When low on health, regenerates all health once.

Grenade Monk: When in combat, suicide bombs an enemy. May or may not survive.

Healer Vortigaunt: Heals friends.

Mad Monk: Does a ton of damage and explodes on death.

Metallic Combine: Has a lot of damage resistance.

Newspaper Monk: Dies after 4 hits with anything.

Portal Combine: Summons 3 friends.

Radio Alyx, Barney, Monk, Rebel, and Vortigaunt: Voicelines have radio sfx.

Shadow Zombie: When low on health, turns transparent and takes no damage.

Shield Combine/Shotgunner: Has a destructable invincibility shield.

Teleporter Zombie: Teleports behind enemies

Wooden Combine: Takes less damage. Not as good as metal.






I hope this was helpful and if I got any information wrong, please correct me!