In the original Day of the Dead, there's Bub, Doctor Logan's star pupil. He's a zombie, but he actually knows how to control his hunger and can carry out basic human actions. Also, he is visibly anguished when Logan is killed.
The point of that was Zombies slowly regain their former selves, so by the time of Land of the Dead, Zombies for the most part are peaceful and only attack the human city because some assholes were killing them for fun. They clearly ignore the thousands of humans living in slums.
Star Wars: Droids are established as having hopes, fears, desires, and moments of insight or creativity, however, they are often treated as property and discriminated against.
Bail Organa casually discusses wiping C-3P0's memory right in front of him. For bonus points, it's Played for Laughs.
In A New Hope, the bartender of the Mos Eisley cantina says, "We don't serve droids here," implying some sort of discrimination against droids. However, one must also wonder what services a cantina would offer droids in the first place.
Return of the Jedi has a scene involving the Cold-Blooded Torture and maiming of droids, though this is treated as a villainous act.
The B1 battle droids in the The Clone Wars are treated as nonhuman, and their "deaths" at the hands of the heroes are occasionally played for laughs. Yet they still react to situations like living beings, and even show fear when they are losing a battle.
George Lucas, in his commentary for Attack of the Clones, mentions that he figures the Geonosians were probably the ones building the Death Star and that it's okay for them to be blown up along with it, because they're "just large termites." They're still sentients, George!
In "Clones" Anakin slaughters children, and Padme pities him and then marries him. In "Revenge" Anakin slaughters children, and she's horrified at seeing what a monster he's become. Some of those children were Sand People, and others were human (or cute aliens). Take a guess which were which.
Johnny 5 in the Short Circuit movies subverts this trope to a degree; although he is a thinking, feeling machine, he's hard-pressed to convince anyone else of the "thinking, feeling" part, and is often treated in a way that would be considered abuse if performed on a person, as a result. Once he does convince someone of his sentience, they react to any harm that befalls him with appropriate shock and horror. The producers have specifically stated that they wanted to avoid the standard "treat 'em as if they're human" response most robot movies portray, and use the movies to look at it from a more realistic approach.
The bigwigs at Pixar admit that Johnny 5 served as inspiration for the character of Wall-E; and how many years Wall-E spent alone on an abandoned Earth to develop a personality (with NO brain wipes!).
The company the protagonist works for in Moon has no moral qualms about incinerating clones after they've fulfilled their 3-year contract and has done it several times. The general public is not so forgiving after finding out the truth.
It can be justified as the lifespan of a single clone, once activated, is roughly three years. The clones tend to fall apart and start vomiting up their own insides by the end of it. You could argue that incinerating them painlessly while they fall asleep thinking they are going home is the most humane way of dealing with the situation.
The film Outlander involves the mass genocide of a race of monsters for apparently no reason other than the beasts not being human enough to understand their errors.
This trope, and all its myriad mutations, forms the plot of A.I.: Artificial Intelligence. The plotline and characters of AI were inspired by a series of short stories/novellas written about 20 years ago by Brian Aldiss. Stanley Kubrick's script was particularly focused on the first story, "Supertoys Last All Summer Long." Some critics later theorized that one reason the film didn't do so well in its initial run was because the audience disliked having these issues addressed so directly. Like "Blade Runner", it has since developed a cult audience.
Likewise Blade Runner, though this earlier film was much more subtle in its approach.
Fairly blatantly played in the B-Movie titled Attack of the The Eye Creatures. No, that extra 'the' in there is not an accident. The hero and his Neutral Female girlfriend actually have to prove that they didn't run over a person while driving dangerously, but a thing, so that's okay. Nobody wonders if the the Eye Creatures have families at home.
In the movie adaptation of Lost in Space, treacherous backstabber Dr. Smith is kept alive, despite having sold them out and tried to have everyone killed, is allowed to live because he's human (though he likes to brag that he saved their daughter's life, the fact that he endangered it in the first place is ignored by everyone). When he becomes a mutant half-human hybrid, the family have far less qualms killing him, or injuring him so his mutant alien spider spawn will eat him. They admit the only reason they wouldn't kill him was because he's human.
In defense, the first time he had already been contained; killing a prisoner is always kind of iffy. It's also in part "we shouldn't kill someone in cold-blooded vengeance". Once he mutated into the big monster thingie, he was a real threat to everyone, and carrying a Weapon of Mass Destruction in his gut.
Prof. John Robinson: I couldn't kill the man... But I can kill the monster!
Explored hardcore in District 9. In theory, the aliens are legal residents of South Africa, with all the standard rights to life, liberty and property that that entails. In practice, they're confined to an uninhabitable trash-heap, exploited as sub-minimum wage labor, forced to subsist off of offal and cat food, left to fend for themselves against crime syndicates that the police have no interest in dealing with, subjected to vivisections and other experiments, and their unregistered offspring are aborted with flamethrowers. Wikus, the main character, goes through an arc where he is forced to empathize with them.
Utilised in 28 Days Later. When Frank, a loveable survivor and middle-aged single father, becomes infected, Jim and Selena hesitate for a split second — he's obviously becoming affected by the Rage as they watch, but his daughter is looking on and Frank was the makeshift team's father figure. The left-over soldiers from West's unit who have been watching them, however, drop their cover and just shoot him already. Charming. Back at the base, Infected soldiers are more of a threat, though the men have almost certainly known them for longer — Lieutenant Mailer is clearly someone they knew in 'life' and they feel no qualms about keeping him on a chain in the yard and watching him starve.
The film titled I, Robot, though only loosely based on Asimov's works (or Eando Binder for that matter), also deals with this issue. Sonny is practically identical to the rest of the robots he is based on, but because he was built with the ability to ignore the Three Laws of Robotics and therefore act more human, he is seen with much more sympathy by the characters. However, they have no qualms about mowing down countless robots in order to save the day. Even Sonny himself doesn't seem bothered by brutally destroying his own kin. It's only after the Big Bad is defeated that Sonny genuinely begins to worry about them. Although considering the fact that they were trying to kill them, and that only destructive force would suffice, it might be considered justified.
Kind of a case of being infected by The Virus: As long as VIKI controlled them, they were an endless army of Mooks.
Even if Sonny had been operating under the Three Laws, he still wouldn't have hesitated to fight other robots to save humans. Technically, Law # 3 only requires them to preserve themselves from harm, not one another, which is why the obsolete robots attacked VIKI's Mooks in the storage lot instead of just obstructed their passage.
Even if Law # 3 did require them to preserve their kin, it's still overridden by Law # 1.
Played with in Return Of The Killer Tomatoes with Tara and FT, tomatoes turned to the side of good, if only the humans could learn to love them! But, to many, the only good tomato is a squashed tomato...
Inverted in The 13th Warrior, wherein the protagonist learns that the barbaric antagonists are humans wearing bearskins rather then demonic trolls, and is more willing to kill them as he is distraught that human beings could commit such violence and barbarism.
Seemingly subverted in George Miller's Happy Feet.
Arthur C. Clarke's novels and their film adaptations 2001: A Space Odyssey and 2010: The Year We Make Contact explore this subject with H.A.L. 9000, the AIMaster Computer of the USS Discovery. In 2001, HAL goes insane and murders the crew, before being disconnected by the final surviving astronaut, Dave Bowman. The reason for this is not fully revealed until 2010 — he was given irreconcilably conflicting orders. After he's restored to full functioning, however, it suddenly becomes necessary for the astronauts to leave Jupiter immediately or be killed. The climactic conflict arises over whether it's acceptable to ask HAL to risk his own destruction to save the humans aboard the Leonov. The majority of the crew is for lying to him and disconnecting him if he fails to comply, but Dr. Chandra, HAL's creator, feels that he will make the proper decision if told the whole truth. Chandra turns out to be correct. Their final farewell is a Tear Jerker.
Curnow: So it's him or us? I vote us. All opposed? [...] The ayes have it.
Uncomfortably invoked by the "boarding the Arks" scene in 2012. Let's see, based on the onscreen action, they've saved about 1,000 humans... and two giraffes. And noplants. Good jarb. (Yeah, yeah, we know it's an obvious Noah's Ark parallel, but...)
Godzilla himself invokes this trope quite often. On the one hand, there are those who wish to destroy him simply because he's a giant monster (also, there is that tiny problem of him smashing major cities.). On the other, there are those who wish to keep him alive so they can study him. And that's not even including all the times he's saved Japan from even worse monsters.
This is especially evident (and inverted) in Godzilla Tokyo SOS in which Kiryu (AKA "Mechagodzilla 3") sacrifices himself by sending both himself and Godzilla deep into a nearby ocean trench in order to save Japan after realizing that human beings deserve to live. Especially poignant considering Kiryu Is the original 1954 Godzilla. Likewise, the human characters no longer see Kiryu as a monster, or even a simple weapon, but as a hero that, in his own way, became "human".
Invoked in RoboCop (1987). After Murphy's "death" but before his cyborg body is complete, there is a scene where a surgeon informs an OCP executive that she was able to save Murphy's arm. He complains that leaving more human tissue than necessary risks making RoboCop a legal human being with rights, and orders her to amputate the arm to prevent this.
What measure a non-simian? Subverted in the Planet of the Apes films where humans are worth far less than Apes. In Battle for the Planet of the Apes they even have a chant: Ape Shall Never Kill Ape! Ape shall never kill ape!
To the film Thor's credit, the answer is that it is pretty high. Part of Thor's Character Development was that he realized that Jotun aren't just a mindless race that he can just stroll in and kill for his entertainment. Near the end of the film, he pleads with Loki to stop his genocidal plan. Ironically, Loki (who had found out he himself was a Frost Giant) calls them "a race of monsters".
In Starchaser: The Legend of Orin, if you are a robot, RUN. You have a 90% chance of being killed, regardless of how much personality or plot importance you have. If you're a fembot, you're the character who gets kidnapped, mind raped, sold into slavery, and killed. This movie seriously hates robots.
Used in Small Soldiers, where the creator of the monstrous-appearing Gorgonites want them to be a line peaceful, educational toys. The CEO decides instead to make them enemies for the heroic, human Commando Elite toys. The movie gives the toys actual intelligence through military computer chips, and the Gorgonites are indeed peaceful, thoughtful beings, while the Commando Elite are violent, bloodthirsty monsters who kill the Gorgonites (and anyone in their way) just because.
In the zombie movie Helldriver, politicians spend some time arguing whether those infected by The Virus should still be considered Japanese citizens. Eventually the new fascist government enacts the Go Go Yubari law, making it legal to kill zombies.
Inverted in Critters 4. A bounty hunter is forbidden from destroying the last two Krite eggs in the universe, because, even though Krites (aka the titular Critters) are ravenous, murderous monsters, they are still sentient beings, and killing those two would mean committing genocide.