Alfie O'Meagan from Nth Man: The Ultimate Ninja is a textbook example: he tortures small animals, shamelessly lies and shifts the blame to others, has sudden outbursts of anger and arrogance, and lacks any sympathy or empathy for others. Problem is, he's also a Reality Warper and the most powerful being on Earth.
There is Sabretooth, who wants nothing more than to torment Wolverine and kill as many people along the way with glee. But he has had a select very few people he cared for. It's been stated he loved his mother, and financially took care of her after he killed his father. He also visited her every two weeks, and put her in the best nursing home in the country when she got ill. Another example would be Bonnie, a human woman he had a brief relationship with after saving her. They spent the night together afterward, and Sabretooth promised to keep her safe with him. He ends up having to kill her— the only woman he cared for who felt the same way about him— which shattered him.
Depending on the Writer, Magneto. While his intentions are far more noble than most characters on this list (at least post-Chris ClaremontCharacter Development) he is also consistently written to Charles Xavier's Foil, and while Charles is (ironically) a Magnetic Hero who makes his X-Men a Family of Choice, Magneto is more often than not a Bad Boss who, in spite of his lofty goals, treats the actual people supporting him as little more than expendable pawns on his chessboard. A special mention should be made for his characterization under Grant Morrison, who chose to write Magneto as an obvious sociopath, so much so that he crossed the line into blatantly Stupid Evil. This characterization proved to be too much for fans to swallow, and a quick Retcon established the Morrison Magneto as an impostor.
The Ultimate version of Magneto takes it even further. He has a massively inflated ego, shows no empathy for anyone, treats his underlings as disposable, and literally views baseline humans as animals to be exploited and killed.
Daredevil villain Bullseye, who lives solely to kill people. He has absolutely no attachments and no compunctions about abandoning a cause to save his own skin.
Purple Man, also from Daredevil, has mind control phermones, which he uses to rape and kill for fun. He tortured Jessica Jones by raping women in front of her, and using his powers to make her watch him. He also once made an entire restaurant stop breathing.
Norman Osborn (aka the Green Goblin), Spider-Man's Arch-Enemy. He's a ruthless, unscrupulous and bigoted schemer who constantly uses everyone around him, hurts innocents with hardly any remorse, slept with his son's wife and manipulated Gwen Stacey to sleep with him, coerced her kids to hate Peter and tricked them into thinking he was their father (when he was) and goes out of his way to make Peter's life miserable. It's fairly stable canon that the Goblin formula doesn't make him evil; it just makes him think he can get away with being evil, along with enhancing existing mental instability.
The original Hobgoblin is also a clear case of sociopathy. He cares for absolutely nothing but money, and eventually manages to get away with retiring because he licensed the Hobgoblin identity, giving him a way to profit off lunatics becoming dangerous supervillains.
Minor Spider-man villain White Rabbit is an exceptionally incompetent one; she's a bored young rich woman who decided to dress up in an Alice in Wonderland costume and commit crimes for the hell of it.
Carnage is a nihilistic chaos-worshipping serial killer who feels absolutely no empathy for anyone or anything except his symbiote and maybe Shriek. And to top it off he's an extremely insane diagnosed psychopath who takes delight in murder. The 2011 "Carnage", 2012 "Carnage USA", and 2013 "Superior Carnage" story arcs revealed that the symbiote he's bonded with is even worse, but appears to have a soft spot for its host as it kept Kasady alive after the Sentry ripped him in half and left him in space, and goes to extreme lengths to get him back when they're separated.
Solus, patriarch of the Inheritors, is a clear example, as he travels around the multiverse killing animal-themed heroes simply to prolong his own life, and got his kids to help out by forcibly transforming them into life-vampires like himself.
The Thousand is quite possible the worst out of all of them. He cares for absolutely nothing but himself and only takes pleasure in hurting others, to the point he murdered his own parents for fun (but not before raping his father). As well, he has a grandiose sense of self and is extremely entitled, viewing it as a personal slight against him that Peter is a beloved superhero and he isn't despite doing nothing to warrant it.
Dr. Zander Rice, the surgical head and lead scientist on the Facility's attempt to recreate Weapon X. He tortures and abuses the preteen X-23 with beatings, treating her as if she were just a thing or animal, exposure to lethal doses of radiation to jump-start her healing factor, by performing the surgery to bond her claws with adamantium a few weeks later by refusing her anasthesia, subjecting her to brutal Training from Hell, and using electric shock and waterboarding to condition her to the trigger scent. Rice is shown to be sleeping with his boss's, Martin Suuter's, wife, even though Sutter practically raised him after Wolverine killed his father, and eventually fathered a child with her. He tests the trigger scent on X-23's martial arts instructor, one of the only people who treated her like an actual human being, precisely for that reason. After a botched attempt to have X-23 killed, he manipulates Sutter to gain control of the program for himself, and then has him and have his inconvenient mistress killed when she threatens to confess to their affair, by sending X-23 to kill Sutter, his wife, and their son (even though he knows the boy is his own child). And then he arranges to have X-23's creator and mother killed by tainting her with the trigger scent to wrap up the last loose end on the project. And throughout the entire project, Rice has Sutter wrapped so tightly around his finger by playing the loving foster son that Sutter is completely blinded to what Rice really is. He kicks one dog after another, to the point even Wolverine killing his father isn't enough to make him sympathetic.
Wolverine's son Daken; he hates his father and cares for no-one but himself, and unlike X-23 he has no problem using his powers to get what he wants and kill off anyone who gets in his way.
Ultimate X-Men (2001): Longshot seems to be one of these, judging by the way he manipulates the X-Men (and Colossus in particular) during his time with them.
