Aliens are diminutive, hairless, yellowish-green-skinned humanoids with short, wiry limbs and green blood. Their heads are disproportionately large, with round, heavy-lidded, solid black eyeballs with no discernible iris or pupil; a thin, toothless mouth with green tongue, and two pairs of small holes where ears and nostrils would be. Aliens have no opposable thumbs, each hand instead having three long, tentacle-like fingers with large suction cups at each fingertip that allow them to manipulate objects. They breathe a similar atmosphere to humans, and (at least those on Mothership Zeta) subsist mainly on a diet of strange, alien worms and squid.
Most aliens encountered are either hostiles or workers. Hostile aliens sometimes have shields which boost their damage resistance significantly. In combat they tend to hang back or rush the player if they are using melee weapons.
Regular aliens are the most common alien the player will see aboard Mothership Zeta. They act as the standard enemy of the area and will always be hostile towards the Lone Wanderer. Aliens have many tiers, depending on the player's level. Tiers 1-3 do not have an inertia suppression field and the aliens tier 4-6 do. Players are able to tell if an alien is wearing an I.S.F. because their bodies will shimmer and become slightly distorted.
The alien captain is the leader of the alien forces on mothership Zeta, equipped with a modified alien blaster and a shiny, gray spacesuit. Despite being the leader of Zeta's aliens, its stats are the same as the lowest-ranking aliens in the game, and its weakness in combat is compounded by its lack of an inertia suppression field. As the ship's captain he has remote access to the mothership's shield and death ray power systems, and a big button in front of it that can fire the death ray.
Alien workers are the working force of the Mothership Zeta. Although displayed as hostile, they will never attack the player, but will flee or cower in fear instead. Killing one results in a loss of 50 Karma although this may not be the case if the player is not directly involved, such as overloading the assembly when they are near it. During the quest Not of This World, when the Lone Wanderer first spots them, Sally will tell the player character not to hurt them because they are harmless. However, if the player manages to get a weapon on Sally (which is not available without the use of console commands), she tries to kill them.
pcps3xbox360 Sometimes, when alien workers appear to cower in fear in front of the player, they may clip into the floor. [verified]
pc Alien workers can cause scripting issues throughout the game. The player's colleagues react differently if one is near, often disrupting scripts. Thus, for example, if there are alien workers in the observation bay area when the Lone Wanderer first enters, when Sally ports through, she may well port straight out again, without opening the doors. If scripting errors occur, it may be advisable to reload to a previous save and kill all the alien workers before trying to trigger a script. This can have a significant impact on your Karma, although a Karma loss can be avoided if another non-player character kills them, such as a friendly drone or abominations. [verified]