Bandits are among the first kinds of enemies that you will fight in the game and come in all sorts of shapes and sizes. While most of them will run around and try to use you as a human pincushion with their guns, there are some of them that like to run and scream right at you, using melee weapons to inflict damage. As one would expect, considering they are humans, their weak point is their head.
Marauders are the basic type of Bandits that like to stay back and shoot at you with their firearms. As you go through the game, they will get stronger weapons, like assault rifles and shotguns, so you need to make sure you always keep an eye out for them. They also tend to go into cover, so they can be difficult to hit.
Psychos are annoying creatures that like to scream and yell, while running towards you to bash your face in with their weapon. They may sometimes stay back and toss weapons at you, which can be a pain since they can be quite accurate with those. Some variants include the Burning Psycho, who can also breathe fire in addition to the previous attacks, as well as the Suicide Psycho, who will charge you while holding a grenade and if close enough, they will kill themselves, causing a lot of damage to you if the explosion catches you.
Nomads are rotund enemies that carry a shield in front of them, that are usually impervious to all bullet damage, meaning you'll most likely need to get on their sides or behind them. The catch with Nomads is that they hate Midgets so much that they strap them to their shields (Nomad Torturers), giving them a literal meat shield on top of their regular shield. You can shoot the ropes holding the Midget(s) to the shield, which will release them and cause them to attack the Nomad.
Bruisers are similar to Marauders, except they are much bigger in size and use the more potentially dangerous weapons, like assault rifles and shotguns. They tend to always move forward and don't try to hide, so they can be easy targets for criticals.
The most dangerous of all the bandits, the Goliath is a large bandit that usually dual-wields assault rifles and wears a helmet on his head. If you should happen to shoot this helmet off, then the Goliath will go berserk and start attacking both friend and foe. Should it happen to kill any enemies for you, it can level up, which restores all of his health and also making him stronger. The max evolution for a Goliath is GOD-liath after killing 10 enemies.