The sixth replicant was a supposed survivor from a group of replicants that escaped an Off-world colony in late 2019.
History
In late October 2019,[1] a group of six replicants led by Roy Batty escaped from an Off-world colony and went to Earth in search of a way to extend their limited lifespans.[2]
Weeks later, when Harry Bryant briefed Blade Runner Rick Deckard on these replicants, he mistakenly[1] told him that one replicant was killed by an electric field and four others survived, leaving one unaccounted for.[3][4][5]
In a plot to destroy the Tyrell Corporation, Sarah Tyrell made use of Bryant's mistake by making it seem there was indeed a surviving replicant and hired Deckard to retire it. She also hired the mercenary Roy Batty, who sought help from Dave Holden.[1]
Batty and Holden eventually came to believe that Deckard was actually the sixth replicant and Deckard was briefly convinced that Batty was such. Eventually, soon after Batty's death, the truth was revealed to Deckard through a persynth of Sarah Tyrell.[1]
Behind the scenes
The concept of a surviving sixth replicant originates from the theatrical and Director's Cut versions of Blade Runner, a remnant from when at least one other replicant character (Mary or Hodge) were to be featured in the film. This error is not present in the workprint version and is fixed in The Final Cut.