I've heard it said that Deckard (Harrison Ford) in Blade Runner is a replicant. I don't remember it being made clear either way.
Is Deckard a replicant? What evidence is there either way?
According to Ridley Scott, yes, he is a replicant.
In the Director's Cut version, the biggest clue for analysts was the appearance of a unicorn on screen while Deckard is lost in thought. The image of the mythical creature appears again towards the end of the film when he picks up an origami model discarded by another character, Gaff. As the replicants had no memories of their own, they had to be implanted, and fans interpreted the appearance of the model as a sign that Gaff knew what Deckard was thinking because it was an image shared by other non-humans.
In Channel 4's documentary On The Edge Of Blade Runner, Scott discusses the scenes and asked what they mean, he confirms with a grin: "He's a replicant".
Another hint in the film comes from the number of replicants which Deckard is hunting. We find out that six had made their way to earth, one of whom was killed. Deckard is looking for four, begging the question: "Who is the fifth replicant?".
You can see the relevant clip here:
I just watched Blade Runner 2049 for the second time and I came up with an interesting theory that addresses the is Deckard a replicant? discussion.
It is mentioned earlier on in the film that replicants can't reproduce, and is further reaffirmed by Wallace who makes some cryptic remarks that boil down to replicants being barren and that Tyrell was the only one who figured it out and did so with Rachel.
Now, even though male replicant reproduction is never explicitly addressed, we know that there is a clear delineation between humans and replicants, in that replicants can't reproduce. If they could, it would be definitive proof that there is no meaningful difference between replicants and humans.
Thus, we can now assume that because Rachel was the only reproductive replicant, and that Deckard had a child with her, he must be (a) a human (b) a replicant who can also reproduce.
(b) seems unlikely given that Wallace would probably find a way of using his genetic code to make a reproductive female and thus eliminate the need for finding his daughter.