Simple critters

Agricola Robot
Built for pre-war uranium mining waste disposal, the Agricola robots can often be found in abandoned mines and nuclear waste facilities. They are extremely well armored and, more importantly, use vacuum tubes instead of integrated circuits. This makes them almost impervious to the electromagnetic pulse weapons that are so deadly to other robots. Agricola Robots are most often equipped with drills and lasers for cutting rock. Used against human beings, they are quite effective.

Ant, Giant
Giant ants are nothing to be laughed up. What they lack in individual fortitude, they make up for with relentless attacks and swarm tactics. Their exoskeleton isn't particularly thick, but it can turn aside weak punches and dull knives. Their mandibles can cut through most leather and plastic with ease, even snapping bone on a lucky shot. Giant ants become particularly aggressive when their queen is threatened.

Ant Queen, Giant
The queen of a giant ant colony is responsible for producing new giant ant workers. Though she is not particularly tough, provoking her will agitate the dozens of subjects that are usually waiting in the wings.

Bat
Bats are annoying little runts with weak bites. For a well-armored character, they can be wasted with impunity. The unfortunate case is that often bats attack in swarms and killing them noisily can alert other, more powerful foes in the area.

Beetle, Electro-
Who knows what created these horrible monsters? Radiation and stray power cables seems to be as good an answer as any. Whatever the case, electro-beetles are fast-moving giant insects that generate powerful electrical fields along their antennae. Prized for their natural energy storage "bio-cells", they are occasionally hunted by the desperate and the brave.

Brahmin
The beloved brahmin of the wasteland are used for their milk, their hide, and their meat. These two-headed wonders are the staple of non-vegetarian diets in the New California Republic and beyond. Well, except for those darn cannibals.

Centaur
The mix of a dog and about six other creatures, centaurs are horrible beasts that look like they came out of an Erol Otus sketchbook. They typically attack with their "mouths" and are extraordinarily strong and hardy.

Centipede, Giant
Normally content to eat passing vermin, these dog-sized creatures are not above attacking the occasional human or ghoul. Like their smaller brothers, they can move very quickly and deliver deadly poisonous bites with alarming speed.

Cockroach, Giant
We always knew the day would come when cockroaches would walk out the atomic firestorm better for the experience. That day is here! Giant cockroaches pack a punch with their bite but, as might be expected, the main problem with them is that they are insanely difficult to kill. Fire, bullets, lasers -- take your pick. Most things bounce right off of them. Only persistence will eventually do these things in.

Coyote
Our friends from the desert are tired of picking off stray cats. In the post-apocalyptic world, they figure they wouldn't mind taking a bite out of the occasional brahmin, ghoul, or human.

Deathclaw
I JUST CANNOT GET ENOUGH OF THESE GUYS. I dropped the hair and the intelligence down just enough to make them the nigh-unstoppable killing machines people remember from Adytum in the original Fallout game.

Desert Stalker
One of the lovely predators unique to the Sonoran desert and its outlying areas, the desert stalker attacks by burrowing up from the ground underneath the victim and biting him with razor sharp mandibles. Desert stalkers have an uncanny ability to go for the weakest person in any group. They will usually attack that person in spite of repeated attacks from others.

Dog
Though beloved as Dogmeat and even Pariah Dog, the player may very well be pushed to hate all dogs given enough encounters. Attacking in packs and regularly taking their opponents down with leg attacks, dogs can be more than a minor nuisance.

Dwarf
Kept for nostalgia, the dwarves of Fallout are just little humans that got messed up by too much radiation in the gene pool. They are pretty much similar to humans, BUT SMALLER.

Floater
Maybe a cross between a plant and a snake, no one was ever quite sure what the floater's freaky deal was. As in Fallout and Fallout 2, they don't move very fast, but once they get to you, they'll slash you to bits with their gaping maws.

Floating Eye Bot
One of the most 50's-esque of the classic Fallout robots, the floating eye bots certainly get around the wasteland. They come equipped with lasers, shock rods, and tranquilizer guns.

Gecko
They come in regular, golden, and fire-breathing varieties, and maybe an extra fun type just for kicks. Giant mutant geckos are a good source of easy hides and the occasional tough combat.

Ghoul
The ghouls of the modern Fallout world are starting to get tired of being pushed around by smooth-skins and have a variety of plans for how to take revenge. Ghouls fight in a variety of ways, but one thing never changes: they are slow as shit.

Gila Monster, Giant
The apocalyptic American southwest would not be complete without giant gila monsters. Normally quite docile, the giant gila monsters may occasionally become violent when they feel their territory is threatened. The main problem with giant gila monsters is not their powerful bite (which is bad), but their radioactive venom (which is worse).

Leech, Giant
These giant, foul creatures can be found in watery places throughout the Fallout world. Once they attach themselves, they very rapidly drain blood from their new friend.

Mantis
Giant preying mantises are not particularly dangerous, but they often attack in packs. They have decent natural armor and their bites, though not individually powerful, can quickly spell death for the unarmored traveler.

Mantrap
Mantraps are carnivorous plants created through genetic engineering prior to the war. Of course, after the war, seeds got out of protected facilities and, well, you know how it goes. Mantraps are not mobile creatures, but they will draw creatures towards them using a strange type of pollen. Once they have trapped a creature, they will use another type of pollen to repel creatures. After they have drained all life from a target, they will drop it.

Molerat
These weird hybrids of moles and rats are not incredibly tough, but they have very sharp senses, making them almost impossible to sneak past. They bite with their ratlike teeth, which are not very powerful, but often carry nasty diseases.

Mr. Handy
He's soooooo handy! Mr. Handy robots are normally used for maintenance in large mechanical facilities like the Box or Tibbets Prison. They are bigger than most humans, and they have a number of strong arms that they can use for a variety of tasks, including the use of weapons in combat. Mr. Handy models are very vulnerable to electromagnetic pulses, but there are a few special Mr. Handy NBS (Nuclear Blast Site) models that are slower, tougher, and equipped with vacuum tubes to prevent EMP damage.

Radscorpion
Appearing in large and hellaciously huge versions, radscorpions are bad news in both sizes. The smaller radscorpions have a more dangerous form of venom in their tail, but the larger radscorpions have much more powerful pinchers. Both versions have tough exoskeletons.

Rat, Giant
Typically found in abandoned buildings and semi-active sewers, the classic giant rat can often sneak up on an unsuspecting traveler. Unlike ordinary rats, these suckers are hungry for flesh. They attack with their teeth, and like molerats, often carry disease.

Robobrain
Robobrains are robots with human brains taken from "volunteers" pre-war. Most often these volunteers were criminally insane, so the robobrains aren’t the most stable group of 'bots ever assembled. They can attack with their hands, but are usually better with weapons.

Scurry Bot
Scurry bots are cat-sized robots that zip around taking care of little things that Mr. Handy's can't deal with. They aren't very strong, but they can survive a light beating. When required to fight, they attack with miniature shock rods.

Security Robot
These are not the Mechwarrior-esque security robots from Fallout 2. They are floating robots somewhat similar to floating eye bots, but far more dangerous. Security robots do not have the extraordinary perception of floating eye bots, but their armor and weapons are much more formidable. 6Typically using extremely powerful shock rods, they will launch a limited supply of explosive rockets at stubborn opponents.

Snail, Giant
Giant snails are no laughing matter to the agrarian cultures of the post-apocalyptic wasteland. Shooting acid and destroying crops wherever they go, they are difficult to get rid of even for patient warriors. Their heads are relatively easy to damage, but their bodies are covered by a nigh-impenetrable shell.

Spore Plant
Spore plants aren't as dangerous as mantraps or thorn-slingers, but if they're unavoidable, they can be problematic for melee and unarmed characters. They shoot out thin thorn slivers that, by themselves, are not particularly harmful. However, spores that miss their target have a small chance of quickly growing into a new spore plant in less than a day.

Super Mutant
First created by the Master and later reproduced by the Enclave, there are a few of these ugly bastards still wandering the wasteland. Super mutants possess tremendous strength and are capable of withstanding everything from baseball bats to pistol fire. They are tough enough to almost make up for their tendency towards colossal stupidity. Though some super mutants make it out of the vats with their minds intact, they are the exception rather than the rule.

Thorn Slinger
Much more dangerous than spore plants, thorn slingers are able to shoot their highly poisonous, armor-piercing darts with accuracy to great distances. Thorn slingers are large, immobile plants, so they are easy to hit -- as long as they don't kill you before you get a chance. Thorn slingers are another wonderful pre-war invention of the Nursery gone horribly wrong.

Turret
Turrets are normally dormant and concealed inside their cylindrical bodies, but when alerted to hostiles, they accurately deal out death at a frightening rate. Turrets can fire standard bullets, rockets, or lasers. Each version is very bad for anyone who comes across it.

Two-Headed Snake
What's worse than a giant rattlesnake? A giant two-headed rattlesnake, of course! Giant two-headed rattlesnakes are annoying for travelers because they often sit in the darkness and blend into the background. Their attacks are extremely quick, their fangs can penetrate light armor, and their venom can kill quickly.

Wasp, Giant
Giant wasps are nasty, hostile creatures that travel in groups of three and go out of their way to find things to kill. They hate seeing humans and animals in their territory and will sting such targets mercilessly until they die from their powerful venom.

Weedling
Weedlings are yet another horrible Nursery creation. They aren't very large, and they can't shoot thorns or seduce people with pollen, but they are mobile. Weedlings are like little plant people who are angry at their state. Weedlings are naturally curious, and will walk up to new creatures without attacking. However, they occasionally will perceive some unintended threat from a creature and an entire pack of them will go into a frenzy. It is up to the individual traveler to decide whether outright aggression or patient caution is the better route for dealing with these weirdos.

Wolf
Wolves almost always travel in packs. Though they are less numerous than the horrible mongrels in Dogtown, wolves are much more individually dangerous and persistent. Wolves have sharp teeth and will frequently knock a target over, then attack the head.