Brahmin. Domesticated, two-headed bovine. Not that difficult, but watch out for Mad Brahmin. They have the same stats as normal Brahmin, but they tend to pop when they get very close to you. Mad Brahmin are only encountered in the special encounter, and when you attack the Keeper of the Bridge Of Death. At least, I never encountered them anywhere else.
HP: 10-15

Wild Dog. Just your normal vicious canine. Not that tough so easy to dispose of.
HP: 5

Lesser Scorpion. Smaller cousin of the Radscorpion, but even this one can poison you. Just attack once and retreat and you'll be safe. Just don't be cornered.
HP: 8 -- Soak: 3

K'Croache.Part Mantis, part Cockroach. SuperNitrous gave mothernature the right juice to create a giant sized combination of the two. These critters has the tendency to come in large groups, and can pose a major problem to civilization.
HP: 3-15 -- Soak: 1-3 (various ages & sizes)

Molerat. Very large variety of the rat species. This one comes in two variants, the Lesser Molerat and the Greater Molerat. The only difference is that the Greater Molerat is a bit stronger and tougher. Both are pretty easy to take down, as long as you are not surrounded by an entire family.
HP: 4-6

Wild Pigs. Common names: Wild boar, wild hog, feral pig, feral hog, Old World swine, razorback
Thi fast, feral, lean mean, tusked omnivorous machines travel in packs and have a voracious appetite.
HP: 3

Rat. This is one of the easiest enemies you will encounter. If you need tips for this one, your village is pretty much doomed. The only attack it has is a bite attack which does little damage. Keep an eye out for the tougher ones though, as their bite can poison you. (rabies!)
HP: 1

Mutie Rats. Another mutation. Sewer rats now have an ugly big brother. It is pretty fast, so a fast character might just be able to outrun it.
HP: 175 -- AP: 9

Gecko. This is a large reptile that walks on his hind legs. It can be pretty dangerous when you encounter a large pack and you get cornered. The Golden Gecko is tougher and faster than the normal Silver Gecko. Watch out for the Fire Geckos, and don't let them come near you. When they do, they shoot flames at you, sometimes twice in a turn. You can skin the Silver Geckos and the Golden Geckos, but the Fire Geckos doesn't have a skinnable hide.
HP: 5 - 10

Giant Ant. SuperNitrous made this tiny insect into a large foe, the exoskeleton makes a natural armor. Look out for its harsh pinchers!
HP: 6 -- Soak: 2

Giant Scorpion. Try to stay out of it's range, as the tail attack can poison you. If you manage to keep out of it's range, you are safe from damage, because the tail attack is the only attack it has. When you kill it, you can take it's tail and turn it into an antidote.
HP: 6-15 -- Soak: 3

Humans. Human adversaries can range from minor pests to downright deadly. They can wield every weapon and armor in the game, and many of them use combat-enhancing drugs, making the battle even more difficult. Make sure you have a big load of Stimpacks on you, even if it is just in case.
HP: Average

Ganger / Highwayman / Robber. Common humans with a common attitude, "Take theirs, before they take mine", be it a tin of food, to the beat from your heart. They come in a variety of flavors, wearing anything you can imagine and wield a large variety of weapons, these are the childrn of the common man left to fend for themselves. Try to keep your distance. They are also frequent drug users (Jet and other combat enhancing drugs).
HP: Average AP: Depends on Armor

Ghouls. The Rotten. The Sub-Human. The Living Dead. There are many terms used when describing one of the greatest horrors you'll find, a foul consequence of the mighty wars that devastated the world and left so many millions starving and diseased. In time, those descendants of humanity that turned to cannibalism to solve these problems, and became a separate race entierly, degenerating over time into babbling, insane beasts closer to zombies than men. Luckily for the surviving communities and societies of the world, ghouls tend to stick to the large urban areas, the great ruined cities, where they can dwell in secrecy and out of plain sight; during daylight hours they tend to remain in sewers and other darkened areas, but as night falls they emerge in great packs to hunt and FEED. In certain cities ghouls are merely a nuisance, while in others they have driven all other life out and rule the rubble uncontested.
HP: Average

Mobs, Gangs, Clans. People tend to band together, and in a time of need and survival, even the feral desperate lives scraping through existance in the wasteland band together. Religious cults, orginized crime syndicates, or just a band of people that agree to steal from anyone but each other.
HP: Average

Tribal Standard tribesman, like yourself in the beginning of the game. Armed with simple weapons like spears and sharpened poles.
HP: Average

Slavers BArtering with the lives and souls of the survivors, this type of group is one to steer clear of.
HP: Average

Yakuza. Eastern warriors, highly skilled and highly deadly. They wield their Wakizashi Blade with amazing skill and can do quite some damage with it, even when you are wearing powered armor. Try to keep your distance and take out from afar. HP: Average

Enclave Trooper. The ultimate enemy. Armed with the nastiest weapons you can find (Gauss Pistols and Rifles to name a few) and donned in Advanced Power Armor. Take them out as fast as you can and try to keep your hp up, as a critical shot from a Gauss Rifle can do an insane amount of damage.
HP: Above Average Soak: See Power Armor

Robot #1, Floating Eye. Small, hovering robot. This one is pretty quick and has only a thrusting attack with it's bottom-mounted prod. Does minor damage, but can be dangerous in large groups.
HP: 20 -- Soak:3

Robot #2 - RoboBrain. Track mounted robot. This robot wields weapons like shotguns, sniper rifles and assault rifles. Can be pretty nasty when it gets a good shot in, so take them out as quick as you can.
HP: 50 -- Soak:4

Robot #3 - Mr. Handy. One of the biggest of the mechanical foes you'll encounter. This robot is pretty tough and can whack you quite hard with it's arms. Energy attacks seem to do the most damage, as will the trusty pulse grenades.
HP: 40 -- Soak: 3

Robot #4 - Sentry. Walking base defense mechanism. Take these things out as fast as you can, because they are armed with rocket launchers and miniguns (the MK. II's can fire 3 rockets in one turn). HP: 80 -- Soak: 8

Turret #1. Fixed base defense mechanism. They are quite resilient to damage and can pack quite a wallop. Use a weapon with as long a range as you got, preferably energy weapons. Try to target the CPU. This one is armed with twin energy weapons.
HP: 60 -- Soak: 4

Spore Plant. Basically a giant Venus Trap that shoots sharp thorns at you or tries to bite you. Stay out of range and shoot from afar.
HP: 7

Alien. One of the strangest enemies, and also one of the tougher. They have high hp and high toughness, and are capable of doing a lot of damage when they can get to you. Take them out with targeted shots in the "eyes / air intake" for maximum damage potential. Don't let them corner you, or you can start writing a farewell note.
HP: 8-20+ -- Soak: Artifact*

Super Mutants. Mutant on steroids. Take caution when you spot one, they are pretty dangerous and usually travel in combat squads of about 6 Mutants. They have high HP and wield weapons ranging from Spiked Knuckles to Gatling Lasers. Also known to wield Flamers and Rocket Launchers. They come in different classes as well. Advice is to keep some distance and take out from afar.
HP: 9-16

Centaur. An old experiment from the Master, this time a huge bloated body with two heads, and six humanoid legs with animal feet attached to it, dragging it's exposed entrails over the ground. It is very tough, and attacks with a sometimes vicious bite. It's not very fast though, so keep your distance and attack from afar. It can poison and/or radiate you, and this bugger's poison is downright lethal, especially when you get multiple doses.
HP: 20

Deathclaw. No one knows where these monsters came from, most likely a very bad but real dream. Some say that the pre-War radiation caused some animal to mutate into a Deathclaw. Other sources say they are engineered by someone or something. Take extreme caution when encountering one, they are very fast, very tough and very strong. When encountering multiple Deathclaws at the same time, try to tackle them one at a time by luring one away from the rest. You can't outrun them, they are simply too fast. You can encounter them in very large packs, so try to separate some from the group or you're toast. And do NOT underestimate the cute little ones, they are almost as dangerous as the larger ones.
HP: 10-15 -- Soak: 1 (tough skin)