Seeing as Hans Landa just went up I'm thinking there might be another Tarantino candidate whose preventions don't really hold up, so here he is (I'm kind of surprised he hadn't been proposed yet). This might be a bit tricky but I think he has a good enough chance at passing.
The work?
Django Unchained is a 2012 film by Quentin Tarantino. It centers around Django, an escaped slave who teams up with former dentist turned bounty hunter Dr. King Schultz, who helps him in his efforts to track down his wife Broomhilda, while exacting revenge on any slaver who they cross paths with.
Who is he and what has he done?
Candie is a notorious slaver who owns the Candieland plantation, where Django's wife Broomhilda has been sold. He's first seen when Django and Schultz arrange to meet him on the pretext that they want to purchase a mandingo fighter, and they witness a brutal fight between one of Candie's slaves, D'Artagnan, and a rival's slave. Candie urges his slave on and when he wins, he throws him a hammer and mercilessly orders him to finish the loser off, which the slave does by caving in the man's skull. Candie then negotiates with Django and Schultz and decides to hear them out when they offer to pay him $12,000.
Some time later they travel toward Candieland but then discover D'Artagnan has escaped and is now crying that he does not want to fight anymore. Candie tells him that he has paid money for five fights and won't accept anything less, mocking the slave's pleas and asking if he will reimburse him. At this Schultz becomes uncomfortable and offers to pay him off, which surprises Candie. Django then steps in and says they won't buy the slave (in order to keep their cover). Candie still seems suspicious and then orders D'Artagnan to be mauled to death by dogs, both as punishment and to gauge Django and Schultz's reaction, and they are forced to watch as the slave is torn apart.
Upon arriving at Candieland, it's revealed Broomhilda tried to escape and is currently being tortured in "the box" but Candie orders her released to make a good impression. His house slave Stephen meets Django and is instantly suspicious of him, trying to interrogate Broomhilda about what's going on. At dinner that night Django and Schultz act like they want to buy the mandingo fighter Eskimo Joe (saying they will return in five days with the money which they don't actually intend to do) and when Candie agrees, Schultz subtly tries to arrange for them to purchase Broomhilda's freedom for a lesser sum, but at that point Stephen interrupts and summons Candie out of the room, where he reveals to him that Django and Schultz are doing all this to get Broomhilda. Candie is infuriated and returns to the dinner, displaying the skull of a long-dead slave and sadistically telling his guests how that slave was made to serve his father for 50 years, then sawing the skull open and telling them that phrenology (a discredited pseudoscience) proves that all blacks are genetically inferior to whites. He then has his men burst in and hold Django and Schultz at gunpoint, before demanding they pay him $12,000 right now for Broomhilda, or he will beat her to death with his hammer right in front of them. They are forced to give him all the money to save her life.
As the deal is being finalized, Candie continues to try to provoke Schultz about how he "got the best of him" though Schultz gets even by casually informing him that Alexandre Dumas, Candie's favorite author, is black. As Django and Schultz are about to leave with Broomhilda, Candie stops them and attempts to humiliate Schultz even further by demanding that he shake his hand before leaving or the deal is off, mocking him for being a "bad loser" and ordering his men to hold the group at gunpoint and shoot Broomhilda dead if Schultz refuses. This is the last straw for Schultz, who is outraged at Candie's atrocities (and likely feels it would be dishonorable to shake his hand since it would mean acknowledging him as an equal) so he pulls a gun and shoots Candie dead, which gets him fatally gunned down by Candie's men in retaliation.
Heinous standard?
This is a bit tricky since the film has many brutal slavers, but even with that in mind Candie still stands out since his actions are even more brutal than most of what we see the other slavers do, particularly having an escaped slave torn apart by dogs and his overall fondness for killing people by bashing their skull in with a hammer, and also enjoys psychologically tormenting his victims such as his racist lecture to Django and Schultz about black people being genetically inferior and the pleasure he takes in extorting them at gunpoint, along with trying to shatter Schultz's remaining dignity by ordering him to shake his hand, which had absolutely no motive other than sadism.
He's also shown to be infamous in-universe for his cruelty with Django grimly noting that all slaves know of Candieland, showing he has a reputation for being especially vicious, and he also has strong personal villainy against all the main characters and is indirectly responsible for Schultz's death and for Django nearly being sold back into slavery. The tone of the film also darkens considerably once he shows up (it seemed more like a comedy until that point) and even Schultz, who's seen plenty of how awful slavery is in general, is taken aback by how sadistic Candie is and how he's willing to brutalize and murder his slaves on the slightest pretext. It says a lot that Tarantino himself said Candie is the only villain he's written who he actually hated, while Leonardo DiCaprio (who played him) called him "deplorable" and kept apologizing to the rest of the cast between takes for the horrible things the character was saying.
Mitigating traits?
First while he often puts up an affable facade and seems to respect Django and Schultz at first, this is only to make a good impression and get money out of them and he drops the act as soon as he doesn't need to play nice, and from then on he alternates between a faux-polite demeanor with a clearly sinister undertone to just screaming threats at them depending on what approach he thinks will be more effective. His attempts to seem cultured are also a facade since he claims to be a Francophile but doesn't even speak French and is unaware that the author of his favorite book is black. It's also implied he might have simply let Django and Schultz leave with Broomhilda if Schultz had shaken his hand, but I don't see that as honorable because once he humiliated them he had no practical need to go further and killing them to no purpose would have been more trouble than it was worth so that's just pragmatic.
The main prevention that's been brought up is that he seems to care for his sister enough that he doesn't want her to see Broomhilda's whipped back and then sends her out of the room to keep her from seeing his subsequent blackmail of Django and Schultz, but after re-watching those scenes I don't think it holds up. His response when she objects to seeing Broomhilda's back isn't that empathetic, he just impatiently goes "Fine, fine, maybe after dinner" like he's annoyed at her reaction, and sending her out of the room before blackmailing Django and Schultz was most likely just to get her out of the way since he doesn't know exactly how she might react so it was likely just to get an unknown element out of the equation. Also his relationship with her overall (which is clearly hinted to be incestuous) is not really portrayed as redeeming and seems to be more out of lust than actual love.
As for his relationship with Stephen, while he does rely on him a lot and allows him quite a bit of power this also seems pragmatic since Candie knows deep down Stephen is the more intelligent and business-savvy of the two so he defers to his judgment when he needs to (while still getting his way on whatever he wants) but the rest of the time he's still glad to publicly order Stephen around and belittle him to make himself look better, so it's clear he just sees him as a useful asset but does not respect him as an equal, and while both Stephen and his sister seem distraught at his death, this isn't evidence that those feelings were reciprocated.
Verdict?
I think so.