Synth



Synths are androids created by The Institute and found in the Commonwealth, with two found in the Capital Wasteland.

Background
Synths, created by the mysterious Institute, are classified into one of three generations depending upon their complexity. Generation 1 synths are purely mechanical humanoids with skeletal appearances; consequently, they are crude representations of living humans. Like their predecessors, Generation 2 synths are also mechanical, but have more advanced frames that are partially or fully covered in plastic panels that serve as "skin"; they might pass for humans if not closely inspected. Generation 3 synths represent the pinnacle of synth technology; with biomechanical bodies capable of respiration, bleeding, consuming, and feeling emotions and sensations, Generation 3 synths are indistinguishable from true humans.

Although it is unknown when each successive generation was developed, the people of Diamond City first encountered a synth that was for all appearances a normal human in 2229, in an incident called the "Broken Mask". The synth, which called itself Mr. Carter, was a synth prototype that was field tested without the Institute Director's approval. Many denizens of the Commonwealth have since become paranoid and prejudiced against synths, fearing they might be abducted by the Institute and replaced with identical copies of themselves. Their paranoia is justified to a certain extent, as some of the most sophisticated synths encountered act as spies and could fool the unaware.

Characteristics
Most encountered hostile synths belong to either Generations 1 or 2, and are armed with Institute laser weapons and Shock Batons.

When fighting against the Gen 1 and 2 Synths, it is possible to shoot off their limbs. This can come in handy if there are too many of them, as the moment one of their arms is destroyed, they may be unable to use their weapons. However, they will then proceed to rush the player and begin attacking them with their remaining arm. Shooting their legs will result in them crawling to the player and attacking them with their hands.

In the mission Call to Arms, Institute synths display a disturbing level of sapience, eerily treading the line between man and machine. The synths' sapience is exemplified in their dialogue, they call out to both the Sole Survivor and Paladin Danse when in the ArcJet Systems building, stating "whoever you are, I know you're there". Synths will also question themselves if they have detected but cannot uncover a target, commenting that their systems may be in need of recalibration. This dialogue, more than anything, hints heavily at the level of potential independence possessed by the synthetic humanoids.

Synth
Weak and disturbingly human like, the generic Synth posses little threat to low level players. Even so they are rarely found solitary and often come in groups of four or so. Armed with institute weapons they are one of the cheapest ways of attaining large amounts of power cells. Like ghouls there limbs can be removed and they will change their tactics accordingly.

Synth strider


Stronger then your ordinary Synth these striders while fairly weak still are significant step up. They like their counterparts use almost exclusively institute weapons, though there are exceptions where they will use shock batons. Likely by the point you meet these enemies they will already replace a good percentage of the Synth enemies you'll meet. Take caution as with most synths they almost always travel in decently sized groups.

Synth leader


Stronger then most Synths, Leaders can pose a dangerous enemy for the unprepared. Unlike most synths, leaders are armored and possess heavily modified institute weapons. They almost exclusively travel with other synths and usually act as the final opponent in synth occupied areas. Those of low level or who have armor specked towards anti ballistic weapons may find these opponents somewhat troublesome.

Appearances
Synths appear in Fallout 3 and Fallout 4. The two synths encountered in Fallout 3, Armitage and Harkness, were ostensibly Generation 3 synths, and Generation 1 and 2 synths were not introduced until Fallout 4.

Behind the scenes

 * Synths share many similarities with the terminators from the Terminator film franchise. The most notable one being that the Generation 1 synths are nothing more than endoskeletons that loosely resemble a human skeleton, just like the majority of terminators created by SkyNet. The Generation 2 synths differ in that they possess artificial skin like the T-600 terminators shown in Terminator Salvation. The Generation 3 synths were designed to look exactly like human beings so that they can infiltrate human settlements undetected, which is the exact purpose of the T-800 infiltrator seen in every Terminator film. Sometimes when in combat with Gen 1 and Gen 2 synths, they will say to the player "You must be terminated." Finally, the biggest similarity is that both the Fallout and Terminator franchises depict a post apocalyptic America destroyed by nuclear war.
 * The Generation 3 synths are much like Replicants from Blade Runner, based on the novel Do Androids Dream of Electric Sheep, in that they are synthetic humans genetically engineered entirely out of organic substances and are virtually indistinguishable from real human beings. This is one of many Blade Runner references throughout the game. In fact, the surname "Deckard," if used in some way as part of the player's name, is one of the names that Codsworth is capable of saying. This is a reference to Rick Deckard from the film. In addition, the test required to enter Covenant measures psychological response to random questions, very similar to the exam that Blade Runners give to suspected Replicants.
 * The hunting of rogue synths somewhat references the movie Artificial Intelligence. The movie depicts a futuristic America where androids are used as servants for various jobs, but they commonly gain self awareness and run away only to be hunted down and destroyed.
 * The exact distinction between Gen 1 and Gen 2 synths is a little vague. In the games files there are three types of non Generation 3 synths, not two. Some are unambiguously gen 1 synths and spawn with a completely exposed mechanical skeleton and typically don't use armor, as seen in Kellogg's memories during Shattered. On the other hand, some are unambiguously gen 2 synths and have intact "skin" which can only be damaged by crippling their limbs, expressive faces, and typically wear clothes, such as the Synth requisition officer. In between these are synths with rigid plastic skin, which typically spawn at least partially damaged and can be blasted off by the player even without crippling limbs, similar to other robots. The last group could represent gen 2's that have begun to decay, but given the more rigid appearance of their skin, they appear to be an earlier model. It could be that Gen 1 synths may have been built with plastic casings that often degraded over time and some units simply have none left.
 * Gen 2 synths bear similarities to the NS-5 robots from the film I, Robot.