You folks are doing a kick-ass job… Very impressed with all the creative names and the different approaches to this project.
Thanks again for participating.
You’ve already got me thinking we should do a similar project for the Scientists and Security Guards…
edit: Especially cool to see that Anmat the Ankh’s first post is in a community project. Welcome aboard!
Headcrab
For the others I can’t shoot out anything right now, that hasn’t been said before. But the first thing that came straight to my mind when I read the OP was Ceiling Pimple for the Barnacle. (Optionally just pimple)
Headcrab
Doing something fun like this… I cannot stay silent anymore!
Snark
-Tic swarm, cockroach
Bullsquid
-Spitter
Vortigaunt
-Lightning trooper
Agrunt (Alien Grunt)
-Big boy, Heavy soldier
Gargantua
-Igniter, Oven
Headcrab
-Kisser
Controller
-Peeled, Air head
Gonarch
-Baby sack, Running sack
Barnacle
-Hanger
Headcrab -> Motherhumper!
All I’ve got is Jumping Chicken for headcrabs.
So some of these have been suggested before. Lets just say I’m seconding them. 
Also, I’m a big fan of just calling most of them ____-thing or referring to mythical creatures like Ankh did. Seems most natural to me. Especially for the first few chapters. I’d love for the first few encounters players have with HECU to have them shooting while saying “WHAT THE HELL IS THAT!? WHAT IS THAT!? KILL IT!” [COLOR=‘Black’]“dewwww it”[/SIZE]
Headcrab:
Headhumpers, Bity-Things[COLOR=‘Black’], vag-face[/SIZE]
Houndeyes:
Shriekers, Dog-Things
Vorts:
Zappers, Slug Men, Zap Goblins (Not a fan of “Shockers”. Could be confused with Houndeye shockwaves.)
A Grunts:
'Roids, 'Roiders, Muscles, Beefcake, Ogres
Barnacles:
Idiot Bait, Hangmen, Noose-Tongue, Tongue-Thing
Snarks:
Roach-Things, Bug-Things, Bug Bombs, Bomb Bugs
Garg:
Big-Thing, Giant-Thing, Godzilla
Controllers:
Flying Babies
Zombies:
Just… just call them Zombies or Zombie-Things. 
Gargantua - Tiny
I don’t know if you want names for the enemies you didn’t list (I don’t think HECU ever fight controllers or ichthyosaurs), but for fun, I’ve thought up some names for them too.
Controller: Floater, Egghead, Witch, Flower-top, Fireball
Ichthy: Shark, Piranha, Mega Piranha, Big Fish, Swimmer
Maybe implement this at the time of Power Up and beyond. We’ve Got Hostiles’s time was their arrival and of course they’re first time seeing aliens. Maybe they should refer them as aliens, bogies, monsters at this time.
headcrab: grabber, leaper
zombie: zombie, zed, infected, hands, mouth/maw
vortigaunt: hostile, ghoul, clicker, shocker, green
bullsquid: squid, land-squid, spitter, croc/crocodile
barnacle: barnacle, rope, trap
agrunt: hostile, heavy, hive, nester, armor, fatty, tubby, ogre
snark: rat, roach, swarm/swarmer, running-nade/bomb, berserkers
ichtyosaur: shark
houndeye: screamer, dog, anus/ass(-dog),
gargantia: (black-) armor, tank, monster, giant, flamer, hostile
controller: floater, ghost, head, shaman, hostile
Headcrab: Jumper, Face-eater, Crab
Zombie: Walker, Crabhead, Zombie
Snark: Tiny, Roach, Swarmer/s
Barnacle: Tentacle, Barnacle
Houndeye: Screecher, Screamer, Tripod/Tridog (seeing as they have 3 legs), Pack
Bullsquid: Spitter, Squidface, Acid-Launcher
Vortigaunt: Zapper, Sparky, Green
Alien Grunt: Hive, Bug Hand
Gargantua: Giant, Big Ugly, Flamehand
Yeahh some of these are kinda “eh.”
Zombie: zombies(rather simple), zulus, brainless, nasties
Snark: Fleas
Barnacle: Roof mouths, man eaters
Houndeye: Wolves, screamers
Bullsquid: Crocos
Vortigaunt: Thunders
Alien Grunt: Jerries (had the exact same idea as Jeff), beemen
Gargantua: Lobster, armoured, cyclop
Lobster? Nice!
Gargantua: Juggernaut
HAHAHA!!! I LOVE IT! 
I like the idea of HECU calling Zombies “Mawmen”
spots a zombified HECU “SHIT, I know that guy!” “Aw…hell, don’t make me do this.”
Headcrab: pety, hopper
Zombie: formd, meat sack, pretty
Snark: itchy
Barnacle: tonque
Houndeye: buddy, pug
Bullsquid: thrower, acid
Vortigaunt: plazma
Alien Grunt: faktor
Gargantua: plazma, fat boy, fucker, mamma
Ok my turn :3
Headcrabs: Headless Chickens 
Zombies: Chickenheads
Houndeyes: Boomdogs
Bullsquids: Snotspewer
Barnacle: Flytrap
Gargantua: Pillbug
Icthyosaur: Greenjaws
Alien Grunts: Beethrowers
Vortigaunts: Tasershands
Snarks: Redflees
Controlers: Monks
Zombie - Shuffler, Panting Thing
Houndeye - Threeleggers
Bullsquid - Tentaclesnout, tentacle-snouted thing
Tentacle - Hydra
Gargantua - Cyclops
Icthyosaur - Giant Piranha
AGrunt - Tinned Meat, Meatloaf
Manta Ray - Bomber, Gunship
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