Bakuryuu Sentai Abaranger: A borderline case is Dr. Mikoto Nakadai, the man is a super smart surgeon who was so bored with his life, that when he became Abare Killer he joined the Evolians and use his powers to what he consider as good use. In which case he formulate his own evil plans that are close to working and make the old villains look comical. It doesn't help the fact that he had a shard of the Evolian god Dezumozorlya.
Todd Alquist is an almost perfectly textbook example of Antisocial Personality Disorder. He appears to be polite and normal but its mostly just because he's emotionally hollow. He murders a kid in "Dead Freight", later describes it as "shit happens" and doesn't seem to understand everyone's objections. He shows a similar lack of empathy or even caring when he murders Andrea in "Granite State" and tortures Jesse in "Ozymandias".
He later develops some kind of close relationship to Lydia, who seems considerably more intelligent and with slightly better social skills, but also has a very weird detachment from the literally dozens of murders she is ordering while simultaneously seeing herself as an ordinary businesswoman.
The Cousins are emotionless hitmen who kill everyone in their way, including innocents who didn't need to die, without flinching.
In Warren's Season 5 appearance he does not exhibit such sociopathic traits. He was more of an Anti-Villain who had created a robot girlfriend and was genuinely bothered when she posed a threat to others and tried to help Buffy contain the threat. However, Word of God is that the writers only made him the worst of the Geek Trio in Season 6 because Tucker Wells' actor (the character had tried to kill the Sunnydale High students with hellhounds in Season 3) was unavailable. Warren would have had Andrew's Anti-Villain conscience and likely a similar eventual redemption arc. It was out of necessity that the writers decided he would have to become a far worse person, wanting the Geek Trio's evil leader to be familiar from a previous episode.
Encounters a "pure psychopath" about once a season. Interestingly, despite the hundreds of cases the BAU have investigated, only 9 characters have been listed as genuinely sociopathic/psychopathic. They are Adrian Bale, Nathan Harris (who was not actually a criminal), Frank Breitkopf, The Boston Reaper, Ray Campion, Raymond Donovan and Sydney Manning, Danny Murphy, and Greg Phinney. Of these, The Reaper is probably the worst, being an utterly amoral psycho who killed people for no better reason than a desire for fame, and went after the police when they dared to try and stop him.
Jeremy from the Season 6 episode, Safe Haven is a 13-year old "budding psychopath", with severe attention deficit problems and antisocial tendencies. He can't pay attention to anything for more than a few minutes, has a serious lack of impulse control, lies complusively and convincingly, killed his neighbour's dog, regularly tortures his little sister, and tried to poison his entire family with rat poison in the Thanksgiving turkey. After being abandoned by his mom he goes on a cross country killing spree as he attempts to return home and murder her, killing entire families and torturing the mothers. He has no real emotions (as is repeatedly demonstrated), but fakes them incredibly well, and at one point expresses a very creepy sexual interest in a girl who can't be much more than ten. Rossi suggests that they should keep him on file for a reason.
CSI: Had a few of these as killers of the week. One possibility is the teenage killer in "Unsual Suspect" and "Goodbye and Good Luck". Another appeared on an earlier episode, and it was even lampshaded how she could switch personalities on a whim.
CSI: NY: Had one, possibly two of these. In one episode, a young woman manipulated an older guy into killing a woman at a French Revolution themed party. Stella is annoyed that they can't prosecute the girl, because she didn't commit any actual crime, she just pulled the strings to get the other guy to act.
The Master from Doctor Who is a classic example, although he will generally stop bothering with the suave act and just enjoy himself once he no longer needs to. He fits all traits, and as such, makes an interesting Foil to the show's Bunny-Ears Lawyer protagonist - Both of them are eccentric geniuses with a childish streak and a love for intellectual challenge, but there is one thing that sets them appart: While the Master can be very charming and suave, he has a complete Lack of Empathy. The Doctor, by contrast, has No Social Skills but is generally well-intentioned.
Dark Oracle: Omen appears to be one of these initially, but his genuine liking of Cally and slow development of human emotion keeps him from falling fully into the trope. Villain of the Week Claudia, who believes "if it feels good, do it," might well be a low-functioning sociopath. And then there's the comic book characters, Blaze (a hot-temperedJerk Ass who has no qualms about breaking a fellow student's arm), Violet (a Manipulative Bitch who enjoys scaring the crap out of her victims), and comic!Sage (who plays mindgames with Lance, screws around, and tries to off several girls with a poisonous snake).
Dexter: Averted with the eponymous Dexter Morgan, the most famous Sociopathic Hero and Serial-Killer Killer on TV, is an example of a sociopath with a 'moral code his father instilled to direct his murderous urges at other killers. As such, he self-identifies as a sociopath but he usually only lies & manipulates his targets or people who are trying to hunt him down or to maintain a facade of normalcy (he initially gets into a relationship with Rita entirely as a disguise). With his Character Development, he's a hybrid of schizoid and sociopath who displays enough guilt, love and empathy to qualify as a reformed sociopath, though it's dubious whether such development is realistic.
Dragnet: As a cop show, it showcases a bunch of them. What follow are some examples that stand out.
The earliest available radio episode involves a gang of holdup men who shared a brace of guns between them on jobs. One of them, Alonso Jackson, is best known for bursting into a liquor store, saying "This is a stickup!" and then letting the clerk have it immediately (shooting him again in the spine later to make sure he's dead).
The final case of the Sixties Dragnet finale, DHQ: The Victims, is the holdup of a mom-and-pop grocery store. When Julio, the husband, implores robber Carl Brooks to leave some dough behind to pay the bills with, punctuates a taunt with three bullets to Julio's stomach. He is completely unmoved later, in the hospital, when Julio's corpse is being wheeled out while his widow is being consoled by the priest who gave Julio his last rites. Both Jackson and Brooks' lives were forfeit, presumably because of the extra meanness of spirit behind the murders.
The Big Rod and The Big Accident both feature remorseless hit-and run drivers. In the former episode, when the grieving widower tells the culprit to be glad the Police got him [the hit-and-run driver] first, because "I would have killed you," and all the culprit can say is "Pretty upset, isn't he?" In the latter episode, the hit-and-run driver tries to take solace in the fact that they elderly couple probably wouldn't have lived much longer anyway. In both cases, a disgusted Friday reads them the riot act.
Mister Daniel Lumis is not a killer, but easily the biggest asshole in the entire franchise. He leaves a trail of kicked dogs everywhere he goes, and then expects the cops to respect his my-wants-trump-all attitude, and to excuse without punishment his wronging of everyone around him.
Elementary has Jamie Moriarty. This version of Moriarty personifies every single aspect of this trope with a more personal and realistic approach. Moriarty blackmails and kills her/his own employees, manipulates people just for fun, doesn't even think twice before ruining anyone's life and uses outright violence without the slightest hesitation, disgust or remorse. In "The Diabolical Kind", she even asks Sherlock, the only one she can relate to, how he manages to empathize with other people and be "one of them".
Galavant has Madelena, the innocent peasant girl forced to marry the evil king, who upon being granted a position of power immediately abused everyone she could and schemed for more. When she and Galavant have a long song together she says that she loves him "as much as someone like me can love anyone", only mentioning sex and how well they look together as why.
Game of Thrones: Quite a number of these characters crop up, including (but not limited to) King Joffrey Baratheon, Gregor Clegane and Ramsay Bolton.
Has a few among its villains, like Arthur and Sylar.
Sylar's own father is a case. When asked why he murdered Sylar's mother and sold him to another family, he replies that he doesn't even remember because "it didn't matter to me."
House: A memorable patient in one episode is identified as a sociopath, by both the short hand and proper medical categorization. Notably 13 only recognizes her as such because she's terrified of her, with House saying it's a survival tactic, implying a common association with sociopaths to predator animals. Ultimately it turns out her apparent sociopathic behavior was actually a side effect of some other unrelated medical problem, and she "reforms" by the end of the episode.
The Sinners from House of Anubis, as a result of being The Soulless and having no conscience. They are manipulative, chaotic, completely uncaring of who they hurt (and do it often just For the Evulz) and determined to get their way. They even seem to have no emotion beyond amusement and anger.
House of Cards (US): Frank Underwood is this long before the show even starts. While the audience may at first be able to sympathize with his desire to screw over the people who wronged him, he progresses into using things like bribery, blackmail, manipulation, threats, and even outright murder with worryingly little restraint. He sees everyone around him as objects to be utilized for his own agenda, his relationship with his wife Claire is strangely loving but incredibly twisted, he has a massively overblown ego that repeatedly causes him to shoot himself in the foot, (namely by needlessly antagonizing people he still actually needs) is a pathological liar, only really seems to care about his own lust for power, and feels no sympathy or remorse for the lives he's ruined to get to where he is. On top of all that, he really only seems genuinely capable of feeling sorry for himself.
iCarly: Nora Dershlit. The only thing she cares about is to make friends, but her perception of what counts as "friends" is so horrifically skewed that she believes locking the iCarly gang in her basement against their will qualifies, ignoring their repeated expressions of the fact they don't even like her, believing she can force people to be her friends. She has absolutely no remorse for holding people against their will and outright tries to murder Gibby when he comes to save the iCarly gang. In her second appearence, she once more holds them against their will by holding Spenser hostage and torturing him on a giant wheel to keep the iCarly gang under control, even implying she can and will kill him if it comes to it. She also shows the Manipulative Bitch qualities of the trope, feigning remorse for her actions to trick the iCarly gang into agreeing to release her from prison and luring them into her trap again. She's also confirmed to be a sociopath In-Universe, even referring to herself as one:
Carly: Nora... You're a nutcase!
Nora: The correct term is disturbed, lonely sociopath.
Every character is a sociopath. They're frequently doing things that are unethical if not illegal, stabbing each other in the back, and no one in the gang is able to stick to a plan.
Dennis deserves a special mention. Some of his actions even leave the rest of the depraved gang disgusted. In one episode, Dennis accidentally admitted that he has no feelings.
He also shows more of the symptoms then the rest of gang. For example; Dennis has the superficial charm, fans sometimes comment on how he seems the most normal yet turns to be the most depraved of them all, plus he's good at getting chicks sometimes. He also seems a very cold calculated yet shallow understanding of human emotion. For example, Dennis' technique to get women (the D.E.N.N.I.S. system) is very cold and calculated but also very unsympathetic and fails to work at the end of the episode. Dennis also has the grandiose sense of self-worth that is a symptom of sociopathy.
In the episode "Psycho Pete Returns", a psychiatrist diagnoses Dennis with Borderline Personality Disorder, a serious mental illness marked by unstable relationships, inability to regulate emotions, and impulsive behavior.
The Kill Point: Mr. Rabbit, who manages to be the Token Evil Teammate of a bank robbing crew. He beats the hostages unprovoked, psychologically tortures one of them for no particular reason, carries around the severed ear of an Iraqi soldier he previously tortured to death, and tells Captain Cali that he considers the hostages "cattle" and "sheep being led to the slaughter." He ends up getting beaten to death by the leader of the team, because Even Evil Has Standards.
Kings has Andrew Cross, who makes for an ugly contrast with the narcissists who compose the rest of his family. A bored, listless young man who admits to viewing other people as things (and doesn't seem to understand that this is wrong), Andrew displays a very limited emotional affect, moves impulsively from idea to idea, and has some very troubling sexual urges, as evidenced by his stalking of his aunt, and his leaking of his cousin's nude photos to the press. In the end, Andrew sides with his father's coup, only to betray him to his uncle Silas when it fails, and then, in the closing scenes of the show release Vesper Abaddon from prison with no prior explanation, all with the same perpetual bored look on his face. Whether Andrew has any genuine goals, motives, or loyalty in him, is left in serious doubt as of the end of the show.
Had a serial-killer prostitute (based on Aileen Wuornos) who displayed the "cocktail personality" where she'd become a troubled mentally-frail patient for the psychiatrist or a seductress for Detective Stabler. Her son was the only thing she cared about and it turns out she killed his mother and kidnapped him as an infant.
One doctor did point out that not all sociopaths are evil unrepentant killers, most of them live normal lives like everyone else in their own way.
The wiki has an enitre page for listing all the sociopaths that have shown up in this show.
Lost: Anthony Cooper, Locke's father, is one of the most chillingly accurate depictions of a sociopath on television. He's a very successful con man who has made an entire career out of manipulating people and then dumping them once he's got what he wants. Sawyer's parents are just two of his victims, and he's not remorseful about that in the slightest. He abandoned Locke at birth, reconnecting with him only to steal his kidney. He has no qualms about murdering anyone who might expose him and even throws Locke out a windowfor trying to reason with him. He's entirely concerned with himself and shows no regret for any of the many lives he has destroyed.
In the Merlin (1998) mini-series, Mordred is blatantly a sociopath. Outwardly a handsome, charming, charismatic young man, Mordred is actually a callous, manipulative, sadistic hothead who wants to conquer Britain and kill his father. He practices archery on his castle's servants, kills several soldiers while laughing and jesting with them, and laughs when his own mother is murdered in front of him. And he's a Super Soldier with the backing of an evil goddess. Yikes.
In the first season, Erich Blunt shows every sign of being one, expressing no empathy or remorse for anything, and with an interest in other people only so far as they please him or he can manipulate them to do what he wants. His PA/girlfriend Ivana shows much the same traits as well.
The second season has Alfred "Alfie" Rentman, leader in a mass murder on a school bus, whose own father (a neurologist) had diagnosed him. There was nothing he could really do about it though, since it's an incurable and untreatable condition.
A better example of this is the head of HR, who shows no empathy for even his closest loved ones and seems incapable of it.
Dominic, the head of the brotherhood gang, is another example. He shows no emotion or concern when a good number of his men are killed because "We all die in the end".
Power Rangers Megaforce had Vrak. He cares nothing for anyone except his one plans, manipulates anyone and everyone around him, crushes Metal Alice's spirit upon her death (in spite of the fact that she saved his life) and mocks his own dead brother.
The Villain Protagonist Jim Profit of Profit is the high-functioning type. He's an amoral and remorseless schemer who manipulates people around him to his own ends (including blackmail and murder) while presenting himself as a charming, likeable guy.
Sergeant Will Strausser, at least as of "Sex and Drugs" is being deliberately set up as one. "Ties That Bind" has Miles Matheson and Strausser discussing the fact that Strausser is one, with Miles pointing out that Strausser was going to be put in a padded room before the blackout happened. "Nobody's Fault But Mine" has Strausser threatening to rape Charlie Matheson to Rachel Matheson's face, and he actually tries to rape Rachel when it's just the two of them alone. Fortunately, Rachel manages to kill him off.
Sharpe has Obadiah Hakeswill, the Arch-Enemy of Sharpe and the reason why he was condemned to 2,000 lashes (of which only 200 were given). Lack of Empathy? Check, just ask Sally Clayton's children, after he raped and murdered their mother, as well as any unfortunate soldier he bullies into staying quiet about his abusive conduct. Consummate Liar and Manipulative Bastard? Double check, as he makes himself appear disciplined in front of superior officers and rapes the wives and girlfriends of the rank-and-file, while getting those who are wise to him in trouble, like Harper, who he framed for the theft of an aristocrat's wife's portrait, condemning him to 100 lashes. Need for stimulation? If there's a pretty woman in the episode, he'll try to rape her and if she has a husband, he'll threaten him too. Narcissist? He believes himself invincible right up to his death. He's even worse in the novels, where his crimes include raping a young girl... when he was 12.
Sherlock: The eponymous character's Arch-Enemy, James Moriarty, is this trope played very straight: he has no empathy whatsoever, is a liar, charmer, and manipulator who easily surpasses Sherlock in all three departments, is a criminal mastermind who has orchestrated scores of crimes—up to and including murder—throughout Europe merely because he was bored, and by the end of season 2 has single-handedly wrecked Sherlock's credibility, career and relationships. The difference between the two is probably best underlined when they first meet face to face.
Sherlock: People have died. Moriarty: That's what people DO!
Subverted by Sherlock himself. While he identifies himself as a "high-functioning sociopath" and is shown to usually have a lack of sympathy for those around him, he is shown to care for various characters (his concern when Mrs. Hudson and John are in danger, his sadness over Irene's alleged death, and his reaction to humiliating Molly at the Christmas party). Word of God is that Sherlock wants to be a sociopath (because caring about people gets in the way) but isn't.
Lx-3, Lex's clone and Shadow Archetype from Season 10's "Lazarus" is a solid example. He spends all his time on-screen committing mass murder, has a Hair-Trigger Temper and a sadistic streak, seems to actively enjoy murder for its own sake, and hates everyone. He tries to kill every person he meets.
Bob Rickman, corrupt salesman with Mind Control powers who has no qualms making his enemies kill themselves or brainwashing innocent people to kill for him. His pesticide plants were massively toxic, spreading cancer and environmental damage, which he took delight in being able to get away with thanks to his powers.
Sam Winchester exhibits classic sociopathic behavior when he loses his soul in season six. Though he becomes an example of a pro-social version, as his interest in hunting remains constant, but his Lack of Empathy becomes his defining character trait. He sees nothing wrong with purposefully letting his own brother get turned into a vampire, letting 150 people get turned into monsters because there's a chance it could lead him and Dean to an Alpha, using a baby as bait, working with Crowley or with killing Bobby Singer in order to avoid getting his soul back among other things. It is implied and later shown that he killed innocents and did some things that arguably would make him cross the Moral Event Horizon and even hardened hunters like Samuel Campbell and Dean are horrified by his behavior.
Dan Egan from Veep. The show is giving less-subtle hints that Dan seems to be of the high-functioning variety. The fact that he reveals that he killed a stray dog as a child to win a dare leaves little room for doubt. He later claims that he once "broke off an engagement at an Applebee's and then ordered dessert."