The Nexus-6 was produced by 2018, when a group of combat model Nexus-6 replicants staged a mutiny in the Off-world colonies. This event prompted replicants as a whole to be prohibited on Earth. The following year, a group of Nexus-6 replicants led by Roy Batty hijacked a transport and went to Earth in search of a way to extend their lifespans.
The Nexus series of replicants – genetically engineered by the Tyrell Corporation – were virtually identical to a human being. Marketed as being "more human than human," the Nexus-6 had superior strength, agility, a wider temperature range tolerance, and variable intelligence depending on the model for use in Off-world mining colonies.
Because of their physical similarity to humans, a replicant could only be detected by anomalies in bodily responses to emotionally charged and sometimes disturbing questions during a Voight-Kampff test.
The Nexus-6 line had a limited lifespan, lasting just four years. Batty and the other replicants returned to Earth to seek more life, but Tyrell said he was unable to alter the genetic make-up of the series.
Batty was perhaps the most perfect of this series, and the one who led a rebellion of replicants back to Earth in search of a way to extend their lifespans. He said he had done "Questionable things." His creator, Tyrell, replied that he had done "extraordinary things." When informed that there was no way for him to live longer, Batty killed Tyrell.
As he sat dying with Deckard on a rooftop, Batty said stated the uniqueness of the Nexus-6 series and their ability to go where no humans had gone, and do things no human had done.
- "I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion; I watched C-beams glitter in the dark near the Tannhäuser Gate. All those moments will be lost in time like tears in rain."