Radroach

Great American Cockroaches, colloquially called Radroaches or simply Giant cockroaches are obviously giant versions of the regular cockroaches mutated by radiation - there was never any doubt that they would survive a nuclear war. Found mainly in underground areas and sewers, these creatures can usually be found in fairly large groups. They feed on the dead, but will go after living creatures if isolated. Their numbers are usually their greatest advantage. Radroaches live mostly in the areas east of California.

It is said that cockroach guts are actually useful in the treatment of radiation poisoning, and are widely used by tribals for that purpose.

Capital Wasteland
Radroaches look similar to real life roaches in the Capital Wasteland, the only mutations they experience being through size, in which they become the size of a house-cat. They are typically the weakest enemy in the game despite bloatflys, dying from one hit from most weapons, save from a BB gun with very low skills.The best way is to have a .32 Pistol or Chinese Pistol, to not waste ammunition or time. They also are one of the few 'hostile' creatures that will not charge a player, initially, even though marked such on the compass and reticule. In fact, when sneaking, if a Radroach spots the player, the [HIDDEN] notifier will, more often than not, change to [DETECTED], rather than [DANGER] or [CAUTION].

Radroaches will attack, however, if the player seems to threaten them, either by having a weapon drawn, invading their territory or it will attack almost any time, when you are in battle with another enemy (which is limited to less than a foot around the creature), or attacking them. Generally, they will spread their wings in warning when they're about to attack. Companions will attack them even when they don't attack or provoke the player.

Two named Radroaches appear in Fallout 3: Fluffy and Jitters.

Midwest
In the Midwest, Radroaches are a common sight in the wasteland. Like in the Capital Wasteland, they can be encountered nearly everywhere, from old buildings to plains. However, they are drastically different and more dangerous than those met in Capital Wasteland. They have a big, protected main body and small legs, and their juice is incredibly poisonous. They are very aggressive and attack every human unlucky enough to encounter them.

The Midwestern Radroaches are more varied than their Capital Wasteland cousins. Three variations are known:

Small Radroach
The weakest of the cockroaches, they can be easily killed even by a tribal. However, their bites can poison an opponent, and when they are in large groups, they can kill even a prepared combatant. This type of roaches is nearly the same size as their "relatives" in Capital Wasteland.

Large Radroach
They are very similar to their small cousins, but are larger (being approximately the same weight as human) and have an ability to spit their poisonous juice.

Roachor
Roachor is a unique mutant Radroach encountered by the Warrior of Midwestern Brotherhood of Steel. He is an "advanced" version of a large cockroach, who lived in Peoria facility. It appears Roachor was affected by the high amount of radiation coming from a strange production device which was used in manufacturing fission batteries. He is even bigger than any large cockroach, being the same size as a car, his body being radioactivly-greenish and his poison even deadlier. However, the warrior succeeds in killing him.

Appearances
Radroaches appear in Fallout 3 and Fallout Tactics and were to appear in Van Buren. They were also mentioned in Fallout Bible 1.