There is an invisible value placed on the existence of non-human characters in fiction, compared with the value of the life of a human. Killing/destroying one may or may not be the same thing as killing a human. The difference between Not Even Human on one end of the scale and Not Quite Human on the other can be a very fine one, and where a series chooses to draw that line can vary as wildly as the writers' imaginations.
Intelligence, emotions, moral compass and whether the character in question is actually alive in the conventional sense are usually what dictate the morality of the situation. But more often than not, it's also based upon the human-like physical and psychological traits the character has (an issue further explored in this blog post). The sliding scale usually goes something like this:
- Plants, protists, fungi, bacteria, and so on and so forth do not count on this scale. Except sometimes when tropes like Plant Aliens, Planimal, Plant People, and When Trees Attack come into play. Or if the organism is a member of an endangered species. Or if you're talking about destroying an entire forest, since that's on such a large scale and since there are animals in the forest that could die or get their habitats destroyed.
- If a Soapbox Sadie is present, you can get a major talking-to for this, but it's never really taken seriously, like the character, and is often played for comedy.
- Undead beings like skeletons, zombies, ghouls, and victims of certain strains of The Virus do not blip at all in this value (despite still being Homo Sapiens). There's hardly any controversy about it either, probably because they're trying to kill you. In fact, killing one is seen as only helping along a natural process.
- There are some exceptions in the very, very rare works where the zombies are not entirely mindless and retain a bit more personality and/or self-control. One example of this (albeit one that some viewers found ridiculous) is the Day of the Dead (2008) remake. It is eventually revealed that certain zombies not only don't eat people, but are completely non-violent. Because of this, multiple characters argue over whether or not it's okay to kill them. They are zombies, but they aren't hurting anyone. More on this in the Film section.
- The value of the life of a non-human animal in fiction, distressingly, tends to relate directly to how much humans like said animal. Thus dogs are protected by Infant Immortality but snakes, spiders and insects are trampled without a second thought. Sadly, this is Truth in Television. To paraphrase an old Denis Leary routine about the Endangered Species Act, "You know how this is going to end! Eventually, only the cute and cool animals will get to live!"
- Monsters of the Week, Giant Monsters and Big Creepy-Crawlies are generally treated as huge pests and exterminated as such without much controversy, typically in self defense. There are some exceptions. If you are a monster, the more you resemble a more conventional specimen of the creature you are based upon, the fewer people you directly harm, and (most importantly) the more personality you have, the better your chances are for surviving. Some human or other will recognize that you are merely misunderstood and may try to help you. Of course, if you eat that human, you're pretty much boned.
- If the Big Bad is revealed to be non-human as a Tomato Surprise or assuming his monstrous true form, it usually makes it OK to kill them if it wasn't before. Double points if that form is that of a snake or other reptile.
- Clones, parallel universe duplicates, and other Doppelgangers are often considered expendable, even if they absolutely are biologically human and sentient and independent individuals with personalities. Restoring an AI from a backup copy is often treated like a Disney Death. This is all provided at least one "instance" of each character survives. ("Sorry, but we only need one flannel shirt-wearing comic relief guy.") The thing is, it should be more like a twin sibling dying, instead it's a more casual Immortal Life Is Cheap. See also Angsty Surviving Twin.
- Vampires, although technically among the undead, have variable ranges simply because they usually have more personality. Most characters can kill them anyway even if they're Technical Pacifists. Certain depictions of Batman and King Graham from King's Quest have killed off Dracula with favorable karmic results (With Graham, the Fan Remake takes a different route), even when killing anything is anathema to them. The idea here, as well as with the other undead mentioned above, may be "Well, technically, they're already dead, so it's okay! And anyway, Vampires are Always Chaotic Evil!"
- Robots and Artificial Intelligence stories examine this quite a lot in their plots, for example in the writings of Isaac Asimov. Good robots and other Mechanical Lifeforms are considered people most of the time. Killing one is generally the karmic equivalent of killing a human the same way — except that it is easier to show them getting hurt (think of poor Bishop in Aliens), which gets awkward. Mecha-Mooks and bad robots almost always have a very low value in this regard, even if they demonstrate obvious personalities, emotions, and humanlike intelligence. Regardless, robots are the most frequent victims of the "How Did You Know That Mook Wasn't Human?" "I Didn't!" trope. It's Just a Machine, after all. It probably helps that when a robot dies We Can Rebuild Him more easily than bring back a human (which is a source of superiority as well: human life is more complicated, probably because robots are almost always written as not having souls even if they are sentient), making them more expendable.
- Supernatural entities vary depending on alignment. Typically demons are on the same level as undead.
- And then there is an uncomfortable border line occupied by characters who are human — but since they aren't "normal", they aren't considered as such. Good Cyborgs, if the brain is still intact, are almost always considered human, except by the persecutors who harass them. Bad Cyborgs are treated on the same scale as Mecha-Mooks. Other "partially disembodied" entities, whether they once were humans or were made like that run the entire spectrum from being accepted as variant humans to "kill them just to end their supposedly nightmarish existence and go drink some Brain Bleach". The same can be said for Transhuman characters.
- Rubber-Forehead Aliens rarely have this problem - as their actors are obviously human, it is easy to transfer the value (this is largely why the trope persists even into the modern, CG-heavy era). Humanoid Animals and Half Human Hybrids tend to get the same protection as a normal human... but it depends on how humanlike they are. If they take up a form that isn't bipedal, rely on their instincts too much, or otherwise start toward the Talking Animal side of things, they can quickly reach the level of monsters-of-the-week.
- As far as other fantastic races, it often seems that the morality of killing the race depends on how much they resemble humans either culturally or physically. Dwarves, elves, gnomes and halflings all look relatively human, and so killing them is bad, but the bestial-looking orcs, goblins and trolls are evil and should be killed. Other races who obviously are not human, but possess cultural traits such as music or clothing styles that the human audience can easily recognize or identify with, are also given preferential treatment over whatever evil races exist.
This is often one of the reasons why Humans Are the Real Monsters. It can get especially awkward, however, when it happens in works of fiction where many of the heroes aren't human either, leading to uncomfortable Fridge Logic.
In general, the more thought that is put into the script, the more value nonhuman life will have. This trope is often used as a metaphor for the Real Life issues of animal and human rights. See also That Poor Plant, Of the People, Zombie Advocate, Inhumanable Alien Rights, Van Helsing Hate Crimes, and Fantastic Racism. The flipside of sorts is What Measure Is a Non-Super?. Related tropes are Uncanny Valley, They Would Cut You Up, and Emergency Transformation. Contrast with Androids Are People, Too.
This also tends to happen in a metafictional way: many animated series and video games can get away with horrific violence and onscreen deaths that the censors would've put a quick stop to (or at least given the work a higher rating) had the victims been human. Robots, the undead, and the like can be brutally impaled, dismembered, and decapitated onscreen, using this trope on the Moral Guardians even if the work itself averts or subverts the trope in-universe.
Examples belong in subpages:
- Anime and Manga
- Audio Plays
- Comic Books
- Live-Action TV
- Tabletop Games
- Video Games
- Web Comics
- Web Original
- Western Animation