A replicant is a fictional bioengineered android in the 1982 film Blade Runner, and in its 2017 sequel Blade Runner 2049. The Nexus-series of replicants are virtually identical to adult humans but have superior strength, speed, agility, resilience, and intelligence, to varying degrees depending on the model. A replicant can only be detected by means of the fictional Voight-Kampff test, in which emotional responses are provoked and a replicant's nonverbal responses differ from those of a human. A version of the test, referred to as a Baseline, is taken by K in Blade Runner 2049 to detect any mental or empathic damage, for which failure means retirement. Throughout the franchise the euphemism "retire" is used when referring to killing Replicants.
Nexus-6 replicants (e.g. Roy Batty) have a safety mechanism, namely a four-year lifespan, to prevent them from developing empathic abilities (and, therefore, immunity to the test). Nexus-7 replicants (e.g. Rachael) were limited experimental models by Tyrell Corporation with a capability to reproduce. Nexus-8 replicants (e.g. Sapper Morton, Freysa), also by Tyrell Corporation, have an open-ended lifespan; however, a rebellion resulting in the "Blackout of 2022" led them to be discontinued and hunted down for retirement. Nexus-9 replicants (e.g. K), by Wallace Corporation, are also open-ended but have increased compliance which makes them incapable of not following human orders, and are thus full slaves. Replicants are sometimes referred to by the slur "skin-job".
In his novel Do Androids Dream of Electric Sheep? (the inspiration for Blade Runner), Philip K. Dick used the term android (or "andy"), but director Ridley Scott wanted a new term that the audience would not have any preconceptions about. As David Peoples was re-writing the screenplay, he consulted his daughter, who was involved in microbiology and biochemistry. She suggested the term "replicating", the biological process of a cell making a copy of itself. From that, either Peoples or Scott--each would later recall it was the other--came up with replicant, and it was inserted into Hampton Fancher's screenplay.
Prior to the events of the film, replicants became illegal on Earth after a bloody off-world mutiny by a band of Nexus-6 models. Two weeks before the starting point of the film, six Nexus-6 replicants escaped the off-world colonies, killing 23 people and taking a shuttle to Earth; the film focuses on the pursuit of the replicants by Rick Deckard, a category of police-officer bounty-hunter called a "Blade Runner", who investigates, tests, and retires replicants found on Earth.
Nexus-6 replicants had been designed to copy humans in every way except for their emotions. The Tyrell Corporation "began to recognize in them a strange obsession", and in order to be able to control them better, started to implant false memories into the replicants in order to give them the years of experiences that humans take for granted; these memories created "a cushion or pillow for their emotions".
Early in the film, Captain Bryant tells Deckard that the Nexus-6 units' possible eventual development of emotional responses was the reason the Tyrell Corporation designed them with a four-year lifespan. Late in the film, Dr. Eldon Tyrell states that the lifespan limitation cannot be circumvented and any attempt to circumvent the limitation kills the replicant during the procedure.
Deckard had no experience with Nexus-6 replicants at the beginning of the film; he and Captain Bryant are puzzled as to why they have risked coming back to Earth and Deckard is unsure how effective the Voight-Kampff test would be on them, as they appeared to have developed human emotion.
Escaped replicants (all Nexus-6 models):
Other replicants (possible Nexus-7 models):
According to Deckard, a normal replicant can usually be discovered using the Voight-Kampff test, after being given 20-30 questions. Rachael answers over 100 questions before Deckard determines it is a replicant. The theatrical cut's voice-over ending said that, as an experimental replicant, Rachael did not have the four-year life but the Director's Cut did not address this. Scott said that he had wanted to cast a young actress in the role to emphasise Rachael's naivety and unworldliness.
The second film further developed Rachael's origin, and gave significantly more details about its radical design. It revealed most significantly that it was an experimental reproductive model of replicant (which ultimately produced a daughter with Deckard) with a high percentage of human organs in comparison to replicant parts. It has an internal human bone structure, natural eyes, hair, skin and reproductive organs, which explains its ability to pass as human. Thus, the film suggests it was only its brain and possibly other vital organs which were the replicant parts. As Rachael died during childbirth, its possible survival beyond the four years was undetermined.
In Do Androids Dream of Electric Sheep?, the android manufacturer, known as the Rosen Corporation, did not know how to manufacture an android capable of living beyond four years. The super-soldiers in Soldier--the spiritual successor to Blade Runner--are intended to be replicants in the film.
The dark, paranoid atmosphere of Blade Runner, and its multiple versions, add fuel to the speculation and debate over this issue. In Do Androids Dream of Electric Sheep?, Rick Deckard (the protagonist) is at one point tricked into following an android, whom he believes to be a police officer, to a fake police station. Deckard then escapes and retires some androids there before returning to his own police station. Deckard takes the Voight-Kampff test and passes, confirming that he is a human.
Harrison Ford, who played Deckard in the film, has said that he did not think Deckard was a replicant, and has said that he and director Ridley Scott had discussions that ended in the agreement that the character was human. According to several interviews with Scott, Deckard is a replicant. Deckard collects photographs which are seen on his piano, yet has no obvious family beyond a reference to his ex-wife (who called him a "cold fish"). The film's Supervising Editor Terry Rawlings remembers that Scott "purposefully put Harrison in the background of the shot, and slightly out of focus, so that you'd only notice his eyes were glowing if you were paying attention... Ridley himself may have definitely felt that Deckard was a replicant, but still, by the end of the picture, he intended to leave it up to the viewer."
Author Will Brooker has written that the dream may not be unique to Deckard and that unicorn dreams may be a personal touch added to some or all of the Nexus-6 replicants' brains. Since we are not privy to the dreams of the other replicants, this is unknown. From this, one could also derive that Gaff is a replicant and may share the same embedded memory.
Paul Sammon, author of Future Noir: The Making of Blade Runner, has suggested in interviews that Deckard may be a Nexus-7, a new generation of replicant who possesses no superhuman strength or intelligence but does have neurological features that complete the illusion of humanity. Scott has mentioned Nexus-7 and Nexus-8 replicants as possibilities in a sequel to the film. Sammon also suggests that Nexus-7 replicants may not have a set lifespan (i.e., they could be immortal).
Sammon wrote that Scott thought it would be more provocative to imply that Deckard was a replicant. This ties back into the theme of "what is it to be human?" What is important is not whether Deckard is a replicant but that the ambiguity blurs the line between humans and replicants.
When Scott was asked about the possibility of a Blade Runner sequel in October 2012, he said, "It's not a rumor--it's happening. With Harrison Ford? I don't know yet. Is he too old? Well, he was a Nexus-6, so we don't know how long he can live. And that's all I'm going to say at this stage".
The sequel Blade Runner 2049 was released in October 2017, which revisited the question while leaving the answer deliberately ambiguous. The film reveals that Deckard was able to naturally conceive a child with Rachael, and this was possible because she was an experimental prototype (designated Nexus-7), the first and only attempt to design a replicant model capable of procreating on its own. The Tyrell Corporation eventually went bankrupt after several replicant rebellions and was bought out by Wallace Corporation, which took over replicant production, but it could not duplicate Tyrell's success with Rachael. Niander Wallace, the sinister CEO of the company, captures Deckard and muses to him about how he met her and fell in love: Wallace thinks it sounds too perfect, and ponders if Deckard himself was designed to fall in love with Rachael, as part of Tyrell's experiment to develop replicants that can procreate (in which case Deckard is a replicant) - but Wallace also admits that with Tyrell dead and the records destroyed, he'll never know, and it is equally possible that Tyrell never planned for Rachael and Deckard to fall in love (in which case, Deckard is probably human).
Although the press kit for the film explicitly defines a replicant as "A genetically engineered creature composed entirely of organic substance", the physical make-up of the replicants themselves is not clear. In the films's preamble, it is noted that replicants are said to be the result of "advanced robot evolution." The preamble also states that replicants were created by genetic engineers. Characters mention that replicants have eyes and brains like humans, and they are seen to bleed when injured. The only way of telling a replicant from a human is to ask a series of questions and analyze emotional responses, suggesting they might be entirely, or almost entirely, organic. The film also shows that at least certain body parts of a replicant are separately engineered and assembled, as shown with Hannibal Chew, a genetic engineer who specifically made replicant eyes. In a deleted scene, J.F. Sebastian was stated to have made replicant hands along with his own personal robotic toys.
During the creation process of a replicant, their physical and mental capacities are separately ranked on a A to C system and designated for each replicant with the C level representing below normal human ability, B level being equal to a normal human and A being above normal human ability, the latter of which leads to superhuman physicality or genius level intelligence.
Do Androids Dream of Electric Sheep? makes mention of the biological components of the androids, but also alludes to mechanical aspects commonly found in other material relating to robots. It states that the bone marrow can be tested to prove whether it is from a human or replicant.
In May 2012, Scott confirmed that the replicants were biological in nature, and contrasted them to the androids in the Alien series:
Roy Batty was an evolved... He wasn't an engine. If I cut him open, there wasn't metal, he was grown... and then within twenty years you get the first bill not passed in the Senate where they applied for replication of animals, sheep and goats and cattle and animals and they turned it down, but if you can do that, then you can do human beings. If you go deeper into it and say 'Yeah, but if you are going to grow a human being, does he start that big and I've got to see him through everything?' I don't want to answer the question, because of course he does... Ash in Alien had nothing to do with Roy Batty, because Roy Batty is more humanoid, whereas Ash was more metal.
The sequel Blade Runner 2049 was released in October 2017. In the intervening 30 years, several major events occurred and new replicant lines were introduced.
The sequel retroactively establishes that Rachael was part of a short-lived prototype line of replicants designated Nexus-7, which was not only intended as a test to make replicants more mentally stable with implanted memories, but to develop replicants capable of naturally conceiving children on their own (all other models before or since are sterile). Rachael died in childbirth in 2021, and the child was hidden by the replicant underground.
In 2020, Tyrell Corporation introduced the Nexus-8 replicant, built with open lifespans not limited to only four years. Tyrell himself had been killed during the events of the first movie in November 2019, and the secret of producing replicants that can procreate died with him. The Nexus-8 went into mass production, but a new wave of replicant rebellions occurred, culminating in rogue Nexus-8's detonating a nuclear weapon in orbit over the western United States, to create an electromagnetic pulse that wiped out all of the electronic records. The Blackout destroyed most records about replicants, making it difficult for humans to track them down on Earth, but the terrorist attack led to mass purges and complete shutdown of Nexus-8 production (though many existing units were able to go into hiding in the chaos).
In 2036, however, genetic engineer Niander Wallace designed a new line of Nexus-9 replicants. They also have an open lifespan, but were designed to be unable to resist orders given by a human, even if that order is to commit suicide. Wallace Corporation had solved a global food crisis with genetically modified crops, which combined with the demonstrated effectiveness of Nexus-9 programming, allowed him to successfully push for the ban on replicant production to be lifted.
By 2049, Nexus-9 replicants are extensively used across Earth and the off-world colonies, but they also necessitate special police units tasked with tracking down any that might go rogue, and any remaining Nexus-8's still in hiding (Nexus-7 was never mass-produced, and all the older models like Nexus-6 simply died of old age decades before). These police units are once again called Blade Runners, but are now openly composed of self-aware replicants (such as officer KD6-3.7), who are fully aware that they are replicants themselves. Like Nexus-7, Nexus-9 models also have implanted memories to aid their mental stability, though they are aware that these memories are fabrications.