And because, in all the Galaxy, they had found nothing more precious than Mind, they encouraged its dawning everywhere. They became farmers in the fields of stars; they sowed, and sometimes they reaped. And sometimes, dispassionately, they had to weed.
The Predators in general. They are a species focused on the hunt, and all of what we see of their culture and technology is obsessively focused towards hunting in all of its forms. The only time we see a Predator engaged in an activity other than hunting is in Requiem, which has a shaky place in the Aliens/Predator canon.
Aunt Abby and Aunt Martha in Arsenic and Old Lace are two of the nicest, sweetest, most generous old biddies you could ever hope to meet. They've also murdered a dozen people with poisoned wine, convinced that because their victims were old gentlemen without any loved ones, that it's an act of charity on par with their donating old toys to orphans. The revelation that their nephew Johnathan is a murderer as well doesn't faze them, though they are horrified when he wants to put one of his victims in the same grave as one of theirs, because that's indecent. They also are completely forthcoming about what they've done.
Mortimer: Aunt Abby, how can I believe you? There are twelve men down in the cellar and you admit you poisoned them. Abby: Yes, I did. But you don't think I'd stoop to telling a fib.
Freaks Of Nature has an alien invasion taking place in the peaceful monster-dwelling town of Dillford and abducting everyone on sight, human or otherwise. Turns out the reason they are doing this is because they are after the veggie riblets, the town's produced snacks which is integral for their meals, and they aren't actually out to harm the population: quite the opposite, they abduct them and keep them inside force-field prisons to prevent the monster half of the townsfolk from harming the human half, which really doesn't work out since their presence unwittingly causes the monsters to break out of control and slaughtering everyone they see. When the aliens finally explain the situation to the townsfolk, they are less than amused.
The Cenobites in Hellraiser, as originally presented. In the world of Hellraiser those who are jaded beyond all sensibility will chase further and further stimulation, raising the baseline to such an extent that their original pursuits no longer titillate and they must seek more and more severe pursuits simply to feel something. The line between pain and pleasure blurs, to the point where only sensation matters. As all practices of hedonism and masochism begin to fail them, some are drawn on a journey to expand their horizons beyond what is naturally possible. Solving the Box is said to summon aid in such a quest, and when the Cenobites come they will provide relief. Sense Freaks of the highest order, the Cenobites are priests in a religion where attaining as much pain and pleasure as possible is the highest aim.
Likewise, inviting the Cenobites by solving the puzzle box, whether you know what opening the box does or not, means they're perfectly free to have their way with you and make you one of them. On one occasion a Doctor attempted to get around this and study the Cenobites by tricking one of his patients into opening the box, but the Cenobites ignored her to focus on him. The patient might have been the one who solved the puzzle box, but the doctor was the one who was inviting them.
In Jupiter Ascending, nobody outside of Jupiter is genuinely concerned with the harvesting of billions of innocents like the people of Earth and others in order to have the genetic material for Recodes, comparing it to animals being humanely slaughtered for their meat and it being perfectly legal within the system.
The Martians in Mars Attacks! declare war, apparently, because they see a bird; laugh, cry and get angry for reasons incomprehensible to humans; cut off someone's head and keep it alive for no apparent reason; put another person's head on a chihuahua's body, again for no apparent reason; and their language consists of the word "Ack!"
However...while the translation of their..."language" (huge air quotes) is somewhat shaky, if you look at it you can see some kind of reasoning. It seems that, long ago, two races interbred which led to a third race of mutants, who left and colonized somewhere else in the universe. Two possibilities—the mutants were Martians, and we were one of the two precursor races, now they want to kill us for no apparent reason; or we are the mutants and they were one of the two precursors, come to kill us...for nor apparent reason. It's still Blue and Orange Morality, but with the added ambiguity of who or what these "mutants" the Martian Emperor speaks of actually are.
It's heavily implied they're just assholes and the entire invasion is for the lulz.
Leek: You're asking for an explanation for something that can't be explained rationally. You know the buildup of energy before something happens? The way your hair stands up before lightning strikes? John: "Before something happens." Do you mean they cause disasters? Leek: Why would they need to? John: All right, then, are they trying to warn me? Leek: Their motivations aren't human. John: All right, then what do they want? Leek: I have no idea. What you really want is to know: why you? John: Yes. Leek: You noticed them, and they noticed that you noticed them.
Anton Chigurh from No Country for Old Men is described as having a set of rules that make sense to nobody but him. You get some small idea of his moral code in the gas station scene early on in the film where the store manager tries to make light conversation with him. It's revealed that the manager married the daughter of the former owner of the premises and this visibly irritates Chigurh ("You married into it"). He forces the shop owner to flip a coin to save his life for no exact reason. Later, when he makes good on his promise to kill the main character's wife, he allows her the same coin flip to save her life. She refuses, telling him it's his choice, not the coin's. Chigurh refutes this, and kills her because she refused the flip.
Most non-human creatures in Prometheus. Engineers had a hand in creating humans and human culture, but also attempt to kill them whenever they come face to face. Trying to figure out their reasons is one of the mysteries of the film. Also, David's morality is ambiguous. He seems to value knowledge above all else and will place human lives in jeopardy to satisfy his curiosity. If you read between the lines, David's using the Engineer goo on Holloway may have been, in his mind, sanctioned by Wayland, who did tell him to "try harder." Looked at in a certain way, he does even get a kind of informed consent, asking "what would you do for the answers you seek," and taking the reply of "anything" as permission to proceed. Still rather Blue and Orange when compared to regular human ethics, though.
David's sense of morality is directly drawn from his creator, Weyland, who sacrificed the lives of nearly everyone on the Prometheus, a significant portion of his corporation's holdings, and the love of his daughter, on a quest to meet Precursors who very clearly did not want to communicate with humans anymore.
Jeff Bridges plays a very disturbing serial killer in a little known 1993 remake of a 1988 Dutch film called The Vanishing. In the film, he describes how he saved his daughter from drowning, believing that this act earned her adoration. He then decides that he is unworthy of his daughter's love unless he proves to be capable of performing an equal act of evil.
Del Preston in Wayne's World 2. Sought out for his skills as "the world's greatest roadie", Del turns out to be a Cloud Cuckoo Lander who at one point recounts a tale of how he once murdered a candy store owner and his son to provide brown M&Ms for Ozzy (who had been refusing to go on stage). He cheerfully tops his anecdote off with "and Ozzy went on stage and did a great show!" Everyone listening to him is shocked/confused/horrified.
The Mi-Go from the 2011 adaptation of The Whisperer in Darkness are a classic example, in line with what Lovecraft originally had in mind. After Wilmarth, the protagonist, thwarts their plan to open a mystical portal from Yuggoth (read: Pluto) to Earth, and then crashes a plane into the ritual site for good measure, they actually go out of their way to save his brain, place it into one of their cylinders and take him around the cosmos on incredible adventures. Even though he had foiled a plan that had likely been in the works for several centuries, and despite the fact that they said he was unworthy of being anything more that a sacrifice earlier in the film. Their minds work very differently, it seems. They're also repeatedly stated to be Consummate Liars. Another, earlier scene has Wilmarth stumble into one that was on its way to the ritual. The Mi-Go simply kicks Wilmarth out of its way and pays no more attention to him, nor does it inform its buddies of his presence. Had it done so, the ritual would not have been foiled in the first place.
In The Whole Nine Yards, Jimmy Tudeski is an Affably EvilProfessional Killer whose morals only occasionally approach anything resembling conventional morality. He'll threaten a waiter with bloody murder for putting mayo on a burger, play mind games with his depressed dentist friend, kill half a dozen people without batting an eye, and murder his helpless wife to become the sole inheritor to a Tontine… but he won't let his wife divorce him and write herself out of the tontine because divorce is a sin. He gets around this by faking his death, thereby allowing her to move on with Oz without the sin of divorce. She knows he's only faking, but it still makes sense to Jimmy.
The Hutts from Star Wars are viewed by most of the galaxy as untrustworthy crimelords and Corrupt Corporate Executives, and they honestly seem somewhat confused why this is a bad thing. Even the nicer ones are clearly only playing by the rules because it's convenient for them, and you can count down the seconds until they start taking minor 'shortcuts'. All the same they often end up allying with the good guys, both because they recognize the benefits of the kind of peaceful, free universes they tend to create, and because they genuinely fear and dislike the Axe-Crazy behavior of those like the Sith (which after all, often have no profit to them).
Ego of Guardians of the Galaxy Vol. 2. A Celestial with eternal lifespan and god-like powers, he sought to find companionship in the galaxy and, meeting mortal life, found them all disappointing and fleeting. With no other peers, he set out to convert all other planets into extensions of himself so as to finally have company, fully expecting the death of all other lifeforms in the process. The one time he actually succeeded in loving and admiring a mortal as much as himself (Peter's mother), he killed her when he realized he couldn't stay with her and retain his immortality.