Justine from the Amnesia: The Dark Descent expansion pack of the same name is strongly implied to be one, with a healthy dose of Narcissistic Personality Disorder on top of it. She captures her three suitors, tortures and mutilates them to roam her dungeon along with several other hapless bystanders who get roped into a sick "game" of hers where she forces a young woman actually Justine herself after taking a Laser-Guided Amnesia potion into Sadistic Choices about whether or not to save them or be killed herself. Also of note is that Justine's father was a psychiatrist and clearly knew something was wrong with her (and the game is set prior to sociopathy being fully defined) before she killed him.
Assassin's Creed: Syndicate gives us Maxwell Roth. He first appears charming enough to get Jacob Frye onto his side with reasoning that he doesn't like Crawford Starrick giving him orders. Then he shows his true colors in a mission where he attempts to burn a factory full of child workers inside. When Jacob Frye saves the children, Roth decides to burn down a theatre full of innocent people. It has even been stated before that when Roth is angry, that means a lot of people will suffer. Worst of all, when he is finally killed he still feels satisfied, for all the evil that he has committed.
Irenicus and Bodhi from Baldur's Gate II: Shadows of Amn. In their case, it's a magically caused condition, though from what we hear, they weren't exactly nice people before.
Bendy and the Ink Machine: As more of Joey is revealed throughout the game, he begins to exhibit all the traits of a classic sociopath. He has absolutely no empathy for his employees, keeping them in horrible work conditions and replacing them on a whim. He has incredible ambition and ego, often taking credit other people's work while contributing nothing of his own. And he manipulates others with his talk of dreams and belief when in reality, he doesn't even believe his own rhetoric and is merely putting on a facade.
Relius Clover, an unabashed Archnemesis Dad and Abusive Parent extraordinare who, after gaining the ability to see a person's inner soul, views other human beings as tools to be manipulated or guinea pigs to be experimented on because he quite literally can't see them as meaning anything more than simple inanimate objects. And in what can only be considered a seriously messed up logical extreme of the page quote, he even turned both his daughter and his wife into puppets. Completely unapologetically. For Science! And then he attempted to kill his son when he demanded an explanation.
Hades Izanami is a classic Sociopath. She is charismatic, manipulative, and wickedly intelligent, even through her batshit insanity, but is simultaneously utterly bloodthirsty and utterly devoid of anything remotely resembling empathy.
A friendly nerdy character in Bully flat out calls Gary, your supposed "ally" in the game, a sociopath (the main character doesn't know what that means). It turns out the nerd was right, and all it took was for Gary to run out of medication to become a sadistic sociopathic lunatic who takes control of the entire school, ties up the headmaster, and then attempts to take over the entire town.
Wicked of The Caligula Effect has a rather fitting name. She has very low trust in other people, and the biggest thing she derives pleasure from is watching other people's relationships fall apart, be they friendships or romantic relationships. This is why she acts friendly towards Naruko before kidnapping her and trying to get the Go-Home Club to think that Naruko is the real Wicked. Also, it's an indirect cause of her hospitalization — she attempted to push a girl off a bridge after convincing her that her boyfriend hated her, but she trips and falls off the bridge.
Dante's Inferno: Lucifer invented evil by rebelling against God, and has decided to spend his eternal imprisonment trapping any soul he can in eternal torture. He uses his shadow to corrupt people on Earth, sadistically taunting anybody who opposes him. The ending reveals that he has learned nothing from his imprisonment, and simply wants the entire universe gripped in his wretched claws.
While most of the villains in Eternal Sonata are bonafide psychopaths, there are two who stand out the most. Fugue is the sadistic Evil Genius of the group who's Establishing Character Moment has him attacking Frederic and Polka just because he's wet. Meanwhile, the teenageCount Waltz, the Big Bad himself, is just as bad, if not worse. He creates a substance called mineral powder which is said to cure diseases, but also has a side effect of turning people into monsters. Why does he want to do this? So he can have an army to help rule the world as he feels that this is the best way for people to remember him.
The Evil Within: Ruvik definitely qualifies. He showed sociopathic tendencies at first by dissecting animals, and when Laura was assumed to have died, moving on to people. His response to Dr. Jimenez's horror towards the victims of his traps seals the deal on this one:
Ruvik: These vermin? These microbes? They're mine to deal with as I please.
Stefano: Fear...radiates from you. Its beautiful, but not yet finished. I am Stefano and now, you are my art!
Stanislaus Braun of Fallout 3. A heartless Mad Scientist who previously engineered the worst atrocities of the vaults, he's currently living it up in a virtual reality scenario in which he can torture the other real inhabitants to his heart's content. Braun's character is a checklist of all the most notable traits of psychopathy: he's a narcissist, holding his intellect in very high regard and expecting the player to follow his commands without question. He's glibly charming, feigning friendliness in his guise as Betty, and even expresses admiration if you play along with his games - but will turn on you in a heartbeat if you disobey him. He wants to be entertained on a near-constant basis, ultimately deleting scenarios once he's exhausted their potential for fun, and enlists you to amuse him through a progressively more sadistic array of crimes across Tranquility Lane. He lies and manipulates without so much as a guilty twinge, roping thousands of innocent people into the vaults with the promise of surviving nuclear war, offering his own vault residents the hope of enjoying a virtual heaven in the Tranquility Loungers, and manipulates you into cooperating by withholding the location of your father. Finally, he demonstrates a total lack of empathy for anyone he tortures and kills over the course of his games, and takes great delight in observing the suffering of real people - whether it's making a little boy cry, breaking up a happy couple's marriage, or murdering everyone on Tranquility Lane only to bring them back and torture them again. And if you ever manage to Mercy Kill his captives, his biggest complaint is that you took away his toys.
A subtle version of this occurs in the Fallout: New Vegas DLC Lonesome Road. Should the player progress through the area with a positive reputation with any of the three dominant factions in the Mojave, Ulysses will accuse them of being an unthinking pawn of a larger, flawed organization. If the Courier has a poor reputation with all three factions Ulysses will accuse them of being a selfish, shortsighted malcontent who blunders into circumstances with far-reaching implications without the slightest concern for how their actions affect others.
Possibly Kotomine Kirei. He describes himself as never feeling happiness from the happiness of others, only finding joy in their pain and suffering, and being incapable of loving someone else. Interestingly, because he was born to a very religious man, he considers himself a "defective person" and spent most of his life trying to "fix" himself, only to give up ten years before the story. His ultimate goal is to try to understand why a good and loving God would create a seemingly inherently evil person such as himself. He is definitely cunning and manipulative, an excellent liar when he wants to be (he prefers to amuse himself with Brutal Honesty), and is charming in his own way, although the story's protagonist takes an instant dislike to him. Said protagonist later realizes that he actually does like Kotomine, and that the reason he immediately felt a twinge of distaste was because he realized that he subconsciously saw a BIT too much of himself in Kotomine.
Gilgamesh. He has the limited emotional affect, Lack of Empathy, need for stimulation, consummate lying and manipulation abilities, lack of shame or fear, and an inflated ego.
Kefka Palazzo from Final Fantasy VI has no understanding of morality, no impulse control, manipulates the emotions of others, is a rampant liar, and resorts to ever greater extremes to slake his thirst for destruction. Kefka ticks all the boxes. All of this is before he becomes a god.
Five Nights at Freddy's: The Purple Man, otherwise known as William Afton is a sadistic Serial Killer who had killed at least eleven children whose souls would go on to possess the animatronics. As the series progressed, Afton is revealed to be the CEO behind a robotics company, specializing in creating animatronics to abduct, kill and store children inside of their stomach cavities. The fifth game suggests that despite his murders, he did care for his daughter Elizabeth. However, this is turned on its head in the sixth and final game when it is implied that Afton was really planning on making his daughter succeed him as a killer by corrupting her.
Forever Home: Barclyss puts up a convincing Mask of Sanity, but it's clear that he has no empathy for any of his victims or his own subordinates, only caring about his own self-pity about the lack of meaning in his life. While he claims to not enjoy his role as an Omnicidal Maniac, he earlier showed sadistic pleasure in watching Xero struggle to save Enda in the Aquadome, showing that others' suffering is one of the few things to elicit a happy reaction from him. Once he loses Fort Cataclysm, he has a psychotic breakdown, showing a lack of impulse control and a need to be in control of the situation.
Being a sadistic, hypocritical jerk with zero remorse, Dimitri Rascalov from Grand Theft Auto IV is perhaps one of the best examples of a true sociopath played completely straight in the game. This quote by Niko Bellic (in the Deal Ending) puts him best:
"You're a strange man. You killed your best friend. You betrayed everyone who ever came in contact with you. You killed my cousin. I guess...the survival of the fittest thing really meant a lot to you."
Not Important from Hatred is given little backstory, but states that his "whole life is nothing but cold, bitter hatred" immediately prior to loading up several automatic weapons and going on a massive killing spree, showing little emotion as he does so.
Heavenly Sword: Flying Fox, a gleeful sadist who spends his entire screen time brutally murdering people for his own amusement and uses a woman's corpse to lure out her child. In the animated film, he even plots to kill Bohan and overthrow him.
Hades from Kid Icarus: Uprising. He instigates a pointless, international war that results in the deaths of millions of humans for no other reason than to harvest their souls to either create more underworld monsters and do whatever else he wants with them (As well as for his own sick amusement), and has absolutely no remorse for his actions. Even when he helps out during the Aurum Arc, it's not out of alturism, it's only because he wants to be the one to destroy humanity. and he still throws Underworld Monsters in Pit's path to hinder his progress just to screw with him.
Vanitas seems to fit the mold at first, but the origins of the Unversed prove he is a subversion. Rather than being callous and lacking in anything but the most shallow emotions, Vanitas is comprised of nothing but negative emotions. And he creates a new Unversed with every negative emotion he has. A true sociopath would not be able to feel deeply enough to create them in the first place.
Nobodies are by their very nature sociopaths, since they lack the hearts required to form bonds or experience true emotions. The members of Organization XIII function at varying levels, with the exceptions of Roxas and Xion, the former of which is born under very special circumstances and the latter of which isn't even a Nobody. Another member, Axel, does gain emotional care for Roxas and Xion after hanging out with them, but it's only for them; he is still a sociopath in regards to anyone else.
And then Dream Drop Distance reveals that all the nobodies had the potential to grow new hearts and feel emotions all along. Bringing this trope Up to Eleven with Xemnas, the one who lied to them and made them believe they were Sociopaths all in order to manipulate them and gain control of their minds, hearts and bodies. And though he acts the most emotionless of them all, he likely had Terra's heart all along meaning he was just naturally an uncaring monster.
Played absolutely straight with Master Xehanort, the Big Bad of the series and a human to boot, who fits all of the criteria.
The Legend of Zelda series has pulled out its share of notable sociopaths over the years. In order of appearance.
While it's mostly a case of Depending on the Writer, most incarnations of Ganondorf are typically depicted as textbook sociopaths. A power-mad despot feels no remorse for anything and will stop at nothing to obtain the Triforce and rule Hyrule even if it means using murder and manipulation. The only exception to this rule is his Wind Waker incarnation, who was portrayed as a Tragic Villain and a Well-Intentioned Extremist.
The title character of Majora's Mask is a textbook example. It loves all of the pain and destruction it causes, cares nothing about the consequences of its actions, and sees everyone else as nothing more than puppets and playthings to use and throw away.
Twilight Princess has Zant. He was a member of the Twili race who went insane when denied the title of king for his ambition to conquer the World of Light. After making a deal with an imprisoned Ganondorf for power, he seized the throne by force, turning Midna into an imp and transforming his own people into Shadow Beasts by sealing away the Sols. He then led a full fledged invasion of Hyrule, committing more atrocities along the way such as executing Queen Rutela in front of the Zoras for resisting his rule. and forcing Zelda to surrender by threatening her people. When Link and Midna unravel his plans he curses Link to remain in wolf form permanently and fatally wounds Midna by exposing her to light. All done with no remorse whatsoever. The fact that he has the gall to pass himself off as a well intentionedKnight Templar only reinforces his sociopathy.
Skyward Sword has Ghirahim an arrogant and extremely sadistic Demon Lord who seeks to use Zelda's life force to revive his master Demise and pursues this goal with total disregard for the lives around him. Going through his personality traits is going through a sociopath's checklist: superficial charm, feels no remorse for anything, extremely sadistic and relishes the pain he inflicts on others, and will not hesitate to manipulate others if it serves his ends.
A Link Between Worlds has Yuga. A vain and arrogant sorcerer who at first glance seems to be a mere servant of Hilda, helping her in her quest to use Hyrule's Triforce to restore the kingdom of Lorule. At the end of the game, he reveals his true colors when he reveals that he never cared about Lorule's fate and that he was merely using her to obtain all three pieces of the Triforce and rule Lorule as the god he fancies himself as.
Morinth in Mass Effect 2. The mission overview after Samara's loyalty mission even says that her biotic powers would make her an excellent addition to the squad...if her "sociopathic tendencies were mitigated." Though you can kill Samara and recruit her anyway. The codex claims that this is typical of Ardat-Yakshi, or at least much more common than in other asari. How much of this is true, how much is propaganda to justify locking away all Ardat-Yakshi, or how much is just the murderous ones making the rest look bad is left deliberately ambiguous.
Quarian Admiral Daro'Xen displays several classic signs of sociopathy as well. She especially shows it in matters related to the geth, whom she plans to, as a race, mind-wipe and return to their "rightful place" as the quarians' slaves. Tali'Zorah flat-out calls Xen insane when this bit of info comes out, showing that even among the anti-geth quarians Xen's stance is seen as radical. Also, Xen apparently used to perform surgery on childhood toys; Tali's response is predictable. Lastly, she shows unhealthy interest in Legion (your geth squadmate), once expressing the desire to dissect the poor thing to see what makes it tick (which Paragon!Shepard is having none of, by the way).
Dr Henry Lawson definitely counts. He's a Mad Scientist who views everyone as pawns or test subjects for him to use and throw away. Controlled every aspect of his two daughters right down to their DNA and has no problem killing them or using them as Human Shields. He has in fact killed several daughters before Miranda because they weren't "perfect". He also sets up a refugee camp for people fleeing the Reapers, only for them to end up as guinea pigs for his experiments on Reaper tech, by turning them into husks, and killing them when they don't meet his expectations. He claims to be saving humanity, but he's really doing it for his own ego thinking that people in the future would see him as humanity's savior.
The captive on Purgatory known only as Prisoner 403, who finds the screams of others being tortured relaxing!
Prothean society apparently encouraged this, the clearest evidence being that the kidneys of still-conscious salarians were considered a delicacy, with the fear adding flavor.
Ridley establishes himself as a psychotic space dragon by allowing his crew to massacre the K-2L space colony Samus was born to and later fakes empathy when a 3-year-old Samus offers him friendship to lower her guard. Meeting up with the girl again, he recounts eating human flesh to recover from the encounter mockingly telling her that he may have eaten her mother as well.
Second, as hinted at above, is the Lantern King, who views others as his playthings to the point that he'll complain like a petulant child if you "ruin" his fun by returning Nyrissa's heart to her.
The Lantern King: (The crowned living flame slowly turns to you, his glowing mask throbbing in rage. His wrath intertwines with the very essence of the surroundings, making the whole world change.) To drink without quenching thirst. To climb a mountain that has no peak. I staged the performance, and you left it without a finale. You took away Nyrissa, my precious toy, carefully crafted of despair and wrath. I could reduce you to dust, revive you, and turn you to dust once more, here and now. But the universe abhors inelegance. So instead I shall repay you with your own coin!
Persona 3: Takaya Sakaki hits every qualification for this trope. He's manipulative and a liar; he has a shallow, self-indulgent personality; murders people for fun and money; and most importantly, he absolutely lacks empathy. He tries to kill Ken after trying to goad him to get his revenge on Shinjiro, saying that Shinjiro's words about how such an act would corrupt the young boy have no meaning. He is then unable to understand why Shinjiro would then sacrifice himself for him, a sentiment that he later repeated when one of his fellow teammates sacrifices herself for her love interest.
Tohru Adachi in Persona 4, who initially hides behind the mask of a Nice Guy, though when revealed shows himself as a sadistic manchild who finds entertainment in ruining the lives of others with a tendency of violently lashing out at women who spurn his advances. They do seem a bit more humane in the spinoffs though.
Persona 5's theme centers around bring these types to justice through HeelFace Brainwashing via "stealing their hearts," the worst of these being Masayoshi Shido, a member of the National Diet who acts humble and generous towards the public but actually sees himself as the only person worthy of leading Japan, looks down on everyone else including his subordinates, uses and disposes of people like tissue paper, and refuses to accept responsibility for any events that might hold him back from his ultimate goal. One need look no further than both Wild Cards — "Joker" and Goro Akechi — to see how casually this man ruins lives without a shred of remorse; the latter moreso, being Shido's illegitimate son.
In Planescape: Torment, The Nameless One's "Practical Incarnation" was this. Ruthless and completely willing to destroy lives to fulfill his goals, he was responsible for many awful things you learn of through the backstory, including your party's Dysfunction Junction status. Notably this is why he's called Practical rather than Evil like one would usually expect; he did evil things not out of enjoyment of them, but simply because he was convinced they were the most effective and practical ways to get what he wanted.
The real Alex Mercer from [PROTOTYPE]. After all, he "wasn't paid to feel." He was so bad that even The Virus who has taken over his body is a better person than Dr. Alexander J. Mercer ever was.
Shadowrun: Hong Kong has Racter, a Mad Scientist who was diagnosed as this at age 8. In game terms, this is what allows him to have his entire lower-half be robotic - Cybernetics Eat Your Soul simply doesn't apply to him. That said, he also expresses Moral Sociopathy, because he believes that his research into his condition and the aforementioned spoiler could vastly improve humanity's lot.
Clockwerk of the Thevievus Raccoonus. A psychopathic owl and rival to Sly's family that was driven solely by his hatred for them. To that end, he turned himself into a Cyborg just so he could achieve Immortality for the express purpose of hunting down and killing each of Sly's ancestors, ending with his father. Clockwerk's Lack of Empathy is so great that he's not only incapable of feeling empathy, but he also views it as a weakness in others.
Neyla of Band Of Thieves. At the outset of the game she was depicted as a Interpol cop with Black-and-Gray Morality who assists Sly and his gang, but after Ch.3 she reveals a glimpse of her true colors when she betrays the gang and has them arrested, even framing Carmelita as well. Her true colors are fully exposed during the finale where she is revealed to be working for Arpeggio, the leader of the Klaww Gang, during which she betrays him and steals the Clockwerk body for herself. Her repsonse to Arpeggio's astonishment at her betrayal showcases her Lack of Empathy.
Neyla:Stupid Arpeggio. I double crossed Interpol, the Cooper Gang, and the Klaww Gang. What made you think I wouldn't do the same to you?
General Tsao, also of Honor Among Thieves. He manipulates the Panda King into taking up medication to force his beloved daughter, Jing King, into marrying him despite her strong objections, all in the belief that marriage will strengthen their bloodlines. He cares only about family honor, and is not above misogyny, animal abuse, and treating his guards like slaves because he doesn't believe in friendship. It's reached the point that even Sly admits Tsao is the worst of all the villains he faced.
Doctor Eggman is a family-friendly version. Firstly, he has no conscience to speak of, using living creatures as batteries and by extension, experimentation on sentient beings. He is determined to take over the world purely because he deserves to rule the world - while at the same time not being exactly clear on what he'd do afterwards. As well as this, he is always prepared to briefly ally with Sonic against greater evils, then toss him aside once he has no use. He has been known to lie without the twitch of a mustache. Most obvious is his vanity - despite his many, many failures, he continues to fight Sonic with very little variation to his methods. Continuing in that vein, he is portrayed as also being charming and polite even to his enemies. Like most real-life Sociopaths, he also lacks Character Development - while his origins have expanded over the franchise, his goals and methods remain the same.
The Sonic Rivals sub-series has Dr. Eggman Nega, who lacks Eggman's redeeming qualities and seeks to turn the entire planet into a playground of destruction.
Arcturus Mengsk from StarCraft. Reviewing his key personality traits is like reading through a sociopath diagnostic checklist: superficial charm, a grandiose sense of self, pathological lying, a penchant for manipulating others to achieve his own ends, an absolutely astonishing lack of empathy or remorse for any of his actions, and an insatiable lust for power and dominance that drives his every move. He unleashed the Zerg on a planet populated by billions of people just to overthrow a few hundred individuals at most and establish himself as the preeminent political figure among the Terrans of the Koprulu sector. He has no qualms whatsoever about sacrificing those closest to him if it suits his purposes.
Seth, the CEO of S.I.N., is an Evilutionary Biologist who views others as nothing but test subjects and will freely manipulate others to get what he wants. He hosted a tournament to lure Ryu and use his his Satsui no Hadou to complete his BLECE project. Much like Bison, he is extremely arrogant and seeks to rule the world and prove his superiority over humans.
Luca Blight from Suikoden II, the "MadPrince" of the Highland kingdom. You get a good idea of his personality in his Establishing Character Moment in which he orchestrates a massacre of children training to be soldiers on his side to rally up support to restart a pointless war with a neighboring nation, while mocking their deaths and regretting not joining in the massacre. He continues to commit atrocities throughout the game, brutally killing scores of people For the Evulz including his own father, while displaying a level of sadism and Lack of Empathy that disturbs even his underlings. Even during his Final Speech, he not only displays a complete lack of regret for his horrific actions, but actually boasts triumphantly of them while reveling in his unredeemably vile nature.
Super Paper Mario gives us Dimentio who is for all intents and purposes, Mario's Kefka Palazzo and one of the most disturbing examples of this trope in a Mario game. Hiding his monstrous intentions under the veneer of the ditzy jester, he uses his superficial charm to manipulate everyone in the game in order to obtain the Chaos Heart and remake the multiverse in his own image. And it's implied that he's motivated solely by his insanity. He's also very sadistic, killing Mario and the gang with no remorse and cracking jokes about their deaths. He also views love and similar emotions as weaknesses to be exploited. His last act, however, is what hammers home his sociopathy. When defeated for the final time, he leaves a shadow of his power behind to continue controlling the Chaos Heart to ensure that everyone in existence will die with him. Meaning his last act was one that would ensure the deaths of untold trillions. There's a reason why he's considered one of the darkest villains in the Mario series.
Mario & Luigi: Partners in Time has Princess Shroob, the leader of the Shroob race. Though she has the sympathetic motive of finding a new home for her Dying Race, this motive falls horribly flat as she commits various actions that seem driven by pure sadism. Two notable examples are feeding Princess Peach to Petey Piranha in front of a Shroob audience and shooting down the Koopa Cruiser while laughing. Her Lack of Empathy also seems to extend to her sister as she made virtually no effort to free her from the Cobalt Star and showed no indication that she intended to.
Syndicate (2012): Agent Merit's dossier remarks that all Agents are expected to be psychopaths, but Merit is psychopathic even by Agent standards. Also, the corporate, ethically bankrupt Syndicate society effectively fosters a general attitude that the lives of others are meaningless except to the extent they can be used to benefit yourself.
Colonel Jade Curtiss from Tales of the Abyss is a high-functioning example, and very much aware of it. Formerly a Child ProdigyBlack Mage who tortured monsters for fun, he could have been much worse if a mentor hadn't stepped in to give him some sense of morality. As is, his old mistakes haunt him, and it troubles him somewhat that he doesn't understand what it means to end a life.
Rommy in Tales of the Tempest. She has no regard for morality or empathy, and does things (usually manipulating others and killing people) only because they amuse her.
Kyrie Ushiromiya in Umineko: When They Cry displays quite a few elements of this. While she appears to be nice and smart, she also always shows a cold, calculating side, keeping either a faint smile or a deadpan expression. There are a few red flags of her sociopathy in Episode 3 and 5 (where it's mentioned that she can sometimes "think in an extremely cold and ruthless manner"), and Episode 7's Tea Party makes a full display of it. Not only does she claim that she doesn't give a crap for her daughter Ange, but she isn't overly shaken by the death of her husband and accomplice either, and is in fact rather pleased that he is out of the way. Add to that a brief Hannibal Lecture to Eva, and you have one of the scariest characters of the series.
Flowey the Flower from Undertale is a huge one. He cares about no one but himself, exemplified by his philosophy of "kill or be killed." His monologue in the Genocide run reflects a more sympathetic portrayal of The Sociopath than most. Flowey is legitimately upset at his Lack of Empathy, but years of living without the capacity for love have driven him to his sociopathic nature by the beginning of the game, doing whatever he can to feel it again.
It is also implied that the first fallen child, Chara, may have been a sociopath even before their death and return as a demon in the genocide run. When they accidentally poisoned their adoptive father they just laughed, and they later committed suicide so they could merge with Asriel and destroy humanity.
Danny St. John from The Walking Dead, while Danny himself is mostly not explored, due to his limited amount of time on the game, we did find out, he was a cannibal, he killed Jolene just because she knew his secret, and he even gave Lee tips on how to cook him when he got trapped in the bear trap.
From Season 2, we have one William "Bill" Carver, who is happy to beat a man almost to death, smack around an eleven-year old girl, and candidly and remorselessly admits to killing Reggie in cold blood if Bonnie asks. More worrisome is that he claims Clementine is Not So Different, although the truthfulness of this statement is up to the player.
The Witch's House: The titular Witch. Despite killing her mother after finding out that she never loved her, she feels no sense of remorse at all, and ends up using her dead mother to get her father's attention, only to kill him as well when he doesn't even notice her. After making a contract with the demon, Ellen only grew worse. Despite being able to feel empathy for animals (and even then that does not stop her from feeding a frog to a giant snake and killing his tadpoles), she possesses none for humans whatsoever. From her countless victims to eventually Viola, Ellen wants to make anyone love her, and if they refuse, regardless of reasons, she'll kill them off and revel in their suffering.
Zero Time Dilemma has Mira, who, despite seeming normal, is in fact entirely unable to understand emotions, something which drove her to becoming a brutal Serial Killer who cuts out people's hearts in an attempt to comprehend their feelings. She also doesn't care at all for her boyfriend Eric and plans to kill him too. In the epilogue files, though, it turned out that Eric convinced her to turn herself in, and she was honestly pondering how she could redeem herself.
Sylvannas Windrunner turns out to be one post-suicide, as the sheer horror of The Maw(i.e. Wo W Hell) broke her, driving her to make a deal with its ruler to spread death and despair in exchange for power and survival. The next few years shred whatever humanity she had left as she was discriminated by the living and ultimately rejected by her sisters (again), causing her to embrace her role as the new Lich Queen.
Matthias Nilsson from Mercenaries is explicitly stated not to be one. While he has the flat affect, thrill-seeking behavior and seeming amorality, his sociopathic traits are a result of his being The Stoic and a firm believer in that You Can't Fight Fate. He has no problems with killing, because he believes that those he kills are fated to die, and nothing could be done about that. Similarly, he will not die before his time is up no matter what he does. He is also perfectly capable of empathy and emotional reciprocity, has no problems with recognizing his failings, and is possibly the world's worst liar.