Synth

The Synth is a free-thinking android that masquerades as a human being from Fallout 4.

The Synths were created by the Institute as what they believe is to better the Earth after its atomic decemation. However, people have come to fear Synths, as they kidnap human beings, take them to the institute, make exact copies, and (possibly) discard the real individual.

According to Elder Arthur Maxson and the Brotherhood of Steel, the Synth is considered to be much worse than that of the nuke. Also, like the nuke, the Synth has the capacity to cause humanity to become extinct.