1066 and All That: While both good kings and bad kings are recognized, all barons in history are wicked, with the sole exception of Simon de Montfort.
The 13 Clocks: The Duke has killed time so that his thirteen clocks do not move, and sets Impossible Tasks to the princes who want to marry his niece. Finally he reveals that she is not his real niece but a princess he kidnapped and intends to marry; he let the princes try their luck because he was under a curse.
1632: Aristocrats or at least aristocracy tends to come off as evil at first but more complications come later. Even in the first volume Gustavus Adolphus is generally good. A good example appears in The Kremlin Games when the Grantvillers are shocked to find out that the cash-rich Russian high nobility are actually neutral or slightly in favor of abolishing serfdom, and the big supporters of the institution are commoner landowners and petty nobles whose only assets are land and the serfs needed to gather resources from said lands. A Russian Prince even laughs at the simplistic American belief in this trope.
The Adventures of Strong Vanya: Grand Duke Dimitri is a sinister, stone-hearted, power-hungry schemer who disposes of anybody who dares to badmouth him and intends to seize the throne by forcing the Tsar's daughter to marry him. Dimitri is despised by the old Tsar and Princess Vasillisa, and feared and hated by the peasantry who thank God when Vanya comes along and claims the throne.
Alice's Adventures in Wonderland: The Duchess. She may be a subversion though, as she's mostly just a Mood-Swinger and is almost unsettlingly nice when in a good mood. (Alice figured it might have only been the large amount of pepper in the kitchen that gave her such a bad mood the first time they met.)
Belisarius Series: Aristocrats are neither worse nor better than others. There is criticism of it as a system however and the main bad guy, the Malwa is devoted to an ideology of inherited power and usually has not the balancing virtues of aristocrats from other empires.
Spoofed in the short humor piece "The Baronet's Redemption" by P. G. Wodehouse, wherein one Sir Jasper Murgleshaw, at heart a philanthropist, feels obliged to kidnap, rob, and poison people simply because he's a baronet. Then it's discovered that he has no legal claim to the title, and he promptly becomes a Sunday School teacher.
The Black Spider: Hans von Stoffeln, the knight baron who ruled over the main characters' village six hundred years ago, was a nasty piece of work: he worked the farmers nearly to death, imposed high taxes, demanded ridiculous tasks from his serfs and punished dissent and criticism very harshly.
Carrera's Legions: The Marchioness of Amnesty Interplanetary (as in Amnesty International), as part of a future UN that's become a true world government, and over the centuries became a Feudal Future government. The original Marquis of Amnestynote who basically bought the title and position with gold from Terra Nova, paid by Carrera's ancestor to buy arms to fight the proto-United Earth forces and the two marchionesses who have been shown to hold the title prior to Captain Wallenstein being made Marchioness of Amnesty in The Lotus Eaters resemble the stereotypical depiction of the Marquis de Sade.
In Chronicles of the Kencyrath the system in the Kencyr is evil, even if not all the aristocrats really are. Jame, and her twin brother Torisen to a lesser extent, are both frequently disgusted by the behavior of their own Highborn caste.
A College of Magics features the neighboring nations of Aravill and Galazon, which were once duchies in a long-ago kingdom that fell apart. Aravill now styles itself a kingdom, and the King and his family are quite nasty, while Galazon still styles itself a duchy, and the Duchess falls under the "Dukes are relatively nice" exception.
Conan the Barbarian is absolutely rife with these kind of characters going with the theme of "civilized men" being hardly any better than the Barbarian Hero. Some prominent examples are Shah Amurath, King Numedidis of Aquilonia, and the conspirators in "The Phoenix on the Sword" and The Hour of the Dragon who are nobles working to overthrow Conan after he is crowned king of Aquilonia. Female aristocrats like Countess Albiona, Princess Yasmela or Queen Taramis tend to avert this, though that is not to say all of them are good like Salome. Even then, it's very rare to find in the series good noblemen.
The title character is a greatly wronged, yet scheming and vengeful Magnificent Bastard.
The worst of his enemies is Count de Morcerf, who was born to a working-class family and worked his way up to the aristocracy by ruthlessness and treachery. He's not evil because he's an aristocrat; he's an aristocrat because he's evil.
Crest of the Stars has Baron Febdash, who rules a very tiny and pretty much worthless star system but is on something of a power trip, surrounding himself with beautiful women as his servants and locking up his human father out of shame. Pretty much nobody bats an eye when he's executed for getting in Lafiel's way, not even his own family. He is, however, the exception in this series: many of the characters are Abh nobility, including the leads (who are a Count and a Viscountess/Imperial Princess, respectively), and most are depicted as either good or at least neutral. It helps that the Abh take the concept of noblesse oblige really damned seriously, and Imperial Law comes down harshly on any noble who fails to fulfill their duties.
The Dalemark Quartet: All of the earls in South Dalemark are evil, oppressing their people. Although the earls of the North are better, Earl Keril of Hannart and the Countess of Aberath also get up to some rather shady dealings.
Dangerous Liaisons: The Vicomte de Valmont and the Marquise de Merteuil, a pair of licentious Magnificent Bastards who take great pleasure in screwing others over (in every possible sense of the term). Amoral at the very least.
Dark Shores: Most of High Lords of Mudamora (with the notable exception of High Lady Dareena Falorn are cowardly and care nothing about the plight of common people—and at the first sight of trouble flee beleaguered Mudamora, basically content to let people starve and die. Special mention should go to Helene Torrington, who is proud that she was able to buy an expensive ring from a desperate girl for a few pieces of silver.
The Death Mage Who Doesn't Want a Fourth Time: While most aristocrats, like Count Palpapek and Baron Balchesse, don't make the lives of peasants harder, Duke David Marme stands out for being highly racist, as well as seeing commoners as livestock at best, and a pest at worst.
Montesq orchestrated the execution of Nicholas Valiarde's godfather Edouard Viller, a scholar and inventor of mechanical devices able to store magical spells, on false charges of necromancy. Interestingly, the main protagonist Nicholas Valiarde himself is a nobleman (and distantly related to the current Queen) but he is from a noble family that was disgraced due to treason perpetrated by one of its members some generations before; Nicholas lives under a variety of pseudonyms as he has become a conman and a thief in his quest for revenge on Montesq.
Count Macob is a cold and vicious undead necromancer, who during his lifetime became infamous for gory human sacrifices and curse spells. Even after his execution and decapitation he still clung to life, as it were.
Deryni: In the early timeline, Manfred Colquhoun Festil Tarquin MacInnis, Baron of Marlor, is trouble. He's part of the corrupt council, and with his colleagues launches a coup against King Javan Haldane. That third name of his doesn't bode well.
Vimes holds to this belief (he makes exceptions for individual aristocrats, but he's still discomfited at becoming one). It's suggested that this is the reason why his distaste for vampires seems more genuine than his distaste for everyone else — vampires almost always have at least a symbolic connection to this trope (being bloodsuckers and all), and very often are literally this as well.
Baron and Baroness von Uberwald, Angua's parents and morally myopic werewolves. Their son and Angua's brother, Wolfgang von Uberwald, is evil through and through, and almost certainly murdered his other sister.
Wyrd Sisters: Duke Felmet murdered King Verence I and is scarily insane. Compared to his Duchess, however, he's a downright warm and fuzzy guy.
Mort: The Duke of Sto Helit murdered his brother, the kind, and made it fair to do the same to his niece. However, his title is inherited by the much more upright Mort and, ultimately, his daughter Susan.
Jingo: Notable subversion: Samuel Vimes becomes Duke of Ankh. He's unmistakeably Lawful Good and, for that matter, absolutely hates his title.
The Fifth Elephant makes references to a "Marquis of Fantailler", who got into a lot of fights (mostly by way of being called the Marquis of Fantailler) and felt this entitled him to write a book. This book was called "The Noble Art of Fisticuffs" and was mostly a list of places where people weren't allowed to hit him. Whether he was particularly good or bad is never brought up, but it's implied that he was kind of an idiot because, as Vimes notes when Carrot tries to fight according to Marquis of Fantailler rules against an opponent who would have to back off a bit to qualify as dangerous, it only works when both people think so.note This is of course a parody of the real-life 9th Marquess of Queensberry, whose name was given to rules for boxing codified in the 1860s, i.e. the Marquess of Queensberry rules. The real-life Marquess was the father of Lord Alfred Douglas ('Bosie'), outspoken (or reckless, considering the times and who his father was) lover of Oscar Wilde. Angered by his son's relationship with Wilde, he was central to the trial and prison sentence which led to Wilde's early death. If you're a fan of Oscar Wilde, it makes this Marquess pretty evil.
Played with in the form of the Patrician of Ankh-Morpork, Lord Ventinari. He's willing to use such tactics as assassinations, blackmail, and vague threats, Ventinari will often self-identify as an evil tyrant who can do whatever he wants and only limits himself because it is intelligent to do so. Looking back at his reign, however, seems to say he honestly cares for his fellow man, as a whole if not individually, and tends to only screw over people who would game the system for their own benefit. He's been instrumental in putting people like Moist Von Lipwig, Samuel Vimes, and William DeWorde in positions of power where they can actively interfere with the various evil schemes that start off in the city.
Discworld is full of all kinds of Lords and Ladies, including evil ones; the antagonist of The Truth is Lord de Worde (who's also the protagonist's father) Many of them are good, however, like Lady Sybil, or merely bumbling. Also from Discworld, The Lords and Ladies is a local name for The Fair Folk, and Discworld elves are not good at all.
Dove Keeper: Baron Gilles de Rais, a real-life aristocratic serial killer.
Dragonwyck: The patroon system of 18th century New York is portrayed as very unjust. At the head of this is Affably Evil Nicholas Van Ryn, patroon (naturally) of Dragonwyck. However, the rest of the aristocracy is portrayed as mostly mean, unjust, thoughtless, or at least clueless.
In the prequel novels, so was Paulus Atreides, Paul's grandfather for whom he was named and who taught Leto everything he knows. Archduke Armand Ecaz is also not a bad guy.
Emperor Shaddam IV is only good in comparison to Baron Harkonnen. The Emperors throughout the series fall under this trope, even the Necessary Evil ones — God Emperor Leto made himself the most reviled being in history, distrusted and despised even by his closest supporters. It's even revealed in the prequels the Emperor had his elder brother and father murdered to secure his succession.
Count Glossu Rabban, the Baron Harkonnen's nephew, and vassal/subordinate somehow (titles don't seem to have any connection to rank in Dune). A violent brute who was a tyrannical governor to Arrakis when it was in quasi-fief to House Harkonnen and much feared and hated by the population, and even more so when the Harkonnens took it back from House Atreides and his uncle ordered him to squeeze as much spice out of the planet as possible.
Viscount Hundro Moritani in the prequels. As much, if not more, of a bastard than Baron Vladimir Harkonnen (see below). Most of his subjects take after him. His ambassador shoots a rival at a state dinner. He orders the bombing of civilian targets despite the declaration of Kanli, a war limited to military targets. He has his rival's son and daughter kidnapped and publicly executed. When another House condemns these actions, he orders the assault on their planet to steal their most holy relic. An ally of the viscount assassinated the rival's second daughter at her wedding to Duke Leto Atreides (the ally was himself a Duke, by the way). He gets what's coming to him, though.
Eisenhorn: Xenos, House Glaw is an ancient noble family with considerable wealth and political influence over the subsector. They're also covert Chaos worshippers and the ringleaders of a vast conspiracy that's trying to acquire a Tome of Eldritch Lore for sinister purposes.
The Earl of Lenda is an example of the "old and senile" version — though the senility is more a combination of Obfuscating Stupidity and a kindly grandfather.
Baron Harparin allies himself with the evil prince and is a noted pederast.
Eurico the Presbyter: Aristocrats from both sides of the war are portrayed as generally evil: the emirs, sheikhs, and walis on the Arab side get this treatment by default, but not even the Christians are exempt from this: King Roderic is a rapist and a murderer, while Count Julian, Sisebuto and Ebas are traitors that throw their own countrymen under the bus to avenge personal slights or advance their own power. Granted, not all of them are bad like Hemergarda (who is the hero's love interest) and her brother Pelagius (who serves as the Big Good), but they are more like the exception than the rule.
Freckles: Angel fears this trope when she realizes that Freckles's relatives are aristocrats.
"A Lord-man!" she groaned despairingly. "A Lord-man! Bet my hoecake's scorched! Here I've gone and pledged my word to Freckles I'd find him some decent relatives, that he could be proud of, and now there isn't a chance out of a dozen that he'll have to be ashamed of them after all. It's too mean!"
Gentleman Bastard: Practically every aristocrat (and no shortage of the common-but-rich) in the world of the series is a spoiled, myopic monster who lives in luxury to put Versailles to shame, while the cities they rule over are dystopian affairs with enormous poor populations. Only three noble characters are portrayed sympathetically.
Particularly monstrous is the so-called Amusement War in the demi-city of Salon Corbeau, a sort of living chess game played for galleries of rich merchants and nobles using impoverished and desperate peasants who volunteer in exchange for a pittance of money and room and board. Whenever a "piece" is captured, he or she is subjected to whatever ghastly punishments the players desire — torture, beatings, stoning, rape, anything short of killing them deliberately — and none of the aristocrats see anything wrong about this.
There's also mention of a noblewoman who Gentled (reduced to mindless husks wholly devoid of their own volition who have to be prodded to eat, excrete, or move) kittens so her sons could torture them with knives because they were bored.
The villain in The Great Balloon Race is the evil Count Pommodoro who systematically sabotages all of the other balloons in the race.
Grey Knights: Duke Venalitor from the novel Hammer of Daemons is definitely evil. Most notably he's a follower of Khorne, the god of bloodshed and slaughter.
Socrates: "No, Callicles, the very bad men come from the class of those who have power. And yet in that very class there may arise good men, and worthy of all admiration they are, for where there is great power to do wrong, to live and to die justly is a hard thing, and greatly to be praised, and few there are who attain to this."
Several pureblood families, such as the Lestranges, Blacks, and Malfoys, are rich and influential and take every advantage of it they can (extra material on Pottermore reveals that the Malfoys obtained their current fortune and lands from services to William the Conqueror). Contrast this with the Potters, who despite being quite rich themselves have a history of being a lot more humble and generous, and the Weasleys who are considered "blood traitors" and looked down upon due to being less economically well-off.
House of the Scorpion: Matt, while he is not privileged in any way because of his status as a clone in the society, is referred to as an aristocrat (a dirty word in the society he is in) because of where he came from, and because he can play the piano.
In The Iron Teeth web serial all the nobles are ruthless and immoral. For example, Vorscha used to work for a Lord but he decided that it was easier to put a bounty on her head than to pay her mercenary company's wages.
In Johannes Cabal the Detective the main antagonist is Count Marechal, who is more or less the de-facto ruler of the fictional country of Ruritania (the Emperor dies shortly after the book starts and Marechal is technically ruling for the mind-addled young son of the Emperor). He's a hands-on type, a former cavalryman who dreams of conquest and the brains to do something about it.
Juliette: The book that got the infamous Marquis de Sade imprisoned for life. It focuses on the French Aristocracy pre-Revolution and shows them all as being libertines who engage in orgies full of torture, murder, and child rape. Furthermore, they're all united by a secret society called the Sodality of The Friends of Crime. Their crimes aren't limited to sexual ones, as Saint-Fond, a Cabinet Minister, genocides the poor with a man-made famine.
I'm the Evil Lord of an Intergalactic Empire!: Save for very few exceptions (the main character included), pretty much anyone that is a noble in the Feudal Future is a horrible human being that would be willing to murder their subjects just for a bit more of power - all the way up to the Emperor. Hilariously, the main character thinks he's one, but he's actually closer to being the Ideal Hero.
The Kingkiller Chronicle books play with this somewhat. Ambrose Jakis is the son of a rich baron and uses his birth and wealth as an excuse to be a colossal douchebag to everyone and especially Kvothe. On the other hand, Willem and Simmon are both sons of minor nobility and Kvothe's best friends, while Count Threpe is a Cool Old Guy who occasionally helps Kvothe and serves as a patron to a number of musicians and entertainers.
Knight and Rogue Series: In the first book, Michael is sent by his father, a baron, to capture a woman suspected of killing an important noble's brother. Early in his search for the woman, he learns that if she's killed the port town she governs will go to this brother, and thus be part of Lord Dorian's territory, meaning Dorian won't have to pay any taxes there, and Dorian ships a lot. Also, his father was aware of all of this. Michael is less than pleased.
KonoSuba; the nobility isn't really touched on, so they come off as no better or worse than the common folk. Darkness, though, desperately wants a stereotypically evil aristocrat for a husband as she gets off on being treated like an abused prostitute, and the Nice Guy her father betrothed her to does nothing to satisfy her kinks.
In The Land That Time Forgot by Edgar Rice Burroughs, Friedrich von Schoenvorts, the German lieutenant in command of the U-Boat, is also a baron. He commits war crimes and is a Bad Boss to his crew (whipping them for minor offenses). Author Burroughs uses him as an example of what Bowen Tyler describes as being "the Kaiser Breed," expressing contempt for German nobility.
The Lord of Bembibre: Played straight with the Count of Lemos Don Pedro Fernández de Castro, a vicious and cruel man who, driven by unbridled ambition and greed, became owner of a chunk of northwestern Spain by backstabbing everyone. Doña Beatriz remarks that he is feared, hated, and despised by many -specially peasants- but he is loved by nobody.
Lord Peter Wimsey: Lord Peter's older brother, the Duke of Denver, is a bit dense but not a bad sort (his wife the Duchess is a terror, though). And Lord Peter becomes Duke when his brother dies of a heart attack while the estate is burning down. He doesn't like it at all, but he'll do his duty.
Virtually every single member of the Archduchy of Crius's Feudal Future is one manner of scumbag or another. This ranges from their Gihren Zabi-EXPY leader Prince Germanicus to the Serial Killer Baron Octavian Plantagenet. This is explained to be mostly due to the combination of Decadent Court intrigue and their own Social Darwinist policies. Notably, everyone outside the Archduchy considers them to be Card-Carrying Villain types since (at least on paper) egalitarianism is the rule in the galaxy.
Subverted by Cassius Mass, as he's known as Colonel-Count Cassius Mass and "The Fire Count" and is arguably the only non-evil aristocrat in the Archduchy of Crius. He also, notably, was born to his title but earned an identical rank for his wartime service.
In Malediction Trilogytroll aristocrat Duke d'Angouleme and his mother Dowager Duchess. He's a Sadist and a Manipulative Bastard, and he treats humans and mixed-blood trolls with utter contempt. In addition, he is rumoured to have killed his own wife and he plots to overthrow the royal troll family. She is not much better and after all, it was she who brought him up.
Memory, Sorrow, and Thorn: Earl Fengbald is a total ass. He tortures his own people by boiling them alive when they can't make him enough money and leads the army of the Evil King against the good guys.
Michael O'Halloran: Leslie blames a woman's behavior on aping nobility, but Douglas corrects that only some of them are like that.
"I don't pity him half so much as I do her," he answered. "What must a woman have suffered or been through, to warp, twist, and harden her like that?" "Society life," answered Leslie, "as it is lived by people of wealth who are aping royalty and the titled classes." "A branch of them — possibly," conceded Douglas. "I know some titled and wealthy people who would be dumbfounded over that woman's ideas."
Mithgar: Baron Bela Stoke is very evil. Think "expy of Vlad the Impaler if Vlad was also a shapeshifting necromancer" evil.
Montmorency: The Marquess of Rosseley is one of the nicest characters in the series, looking after a man he doesn't know at the request of his brother, being an excellent parent, and uniting with the other main characters in their cause.
Murder at Colefax Manor: Lord Colefax. He commits and orders numerous murders, plans to bomb a Cornish city, and runs a hedonistic death cult.
Neverwhere: Marquis de Carabas. A good guy, and a scheming Magnificent Bastard. Though technically, he's not even really an aristocrat, as he is said to have taken his title from "a lie in a fairy tale". He's also only technically a good guy. More on the 'helping the heroes because there's a lot in it for him' side.
In Northanger Abbey, the narrator comments on how Mrs. Morland knew so little of lords and baronets that she did not warn Catherine against the danger of them.
Överenskommelser: Carl-Jan Rosenschiöld. He's a serial abuser of women, who rapes and nearly kills protagonist Beatrice on their wedding night. We later find out that he has killed one previous wife and driven another previous wife into suicide.
Persuasion: Basically the entire point of the story.
Captain Wentworth, with five-and-twenty thousand pounds, and as high in his profession as merit and activity could place him, was no longer nobody. He was now esteemed quite worthy to address the daughter of a foolish, spendthrift baronet, who had not had principle or sense enough to maintain himself in the situation in which Providence had placed him, and who could give his daughter at present but a small part of the share of ten thousand pounds which must be hers hereafter.
The Peshawar Lancers: Count Ignatieff, who is secretly a member of a cult of devil-worshiping cannibals.
The Pillars of the Earth: William Hamleigh is (briefly) an earl. He's also a brutal, ignorant man who rapes and pillages with nary a second thought.
A Practical Guide to Evil: When fighting against the invasion of the fae of the Winter Court, Catherine's main antagonist is the Duke of Violent Squalls. Notably, he is also antagonistic to the Winter King and all his predecessors on the throne: he thwarts every attempt to create peace between Summer and Winter and always clamours for war.
Pride and Prejudice: Subverted wildly. Mr. Darcy (the nephew of an earl) is portrayed as an arrogant, cruel aristocrat throughout the first half of the novel; it's only when Wickham's perfidy is revealed - and Darcy's explanation that he dislikes the Bennets due to their horrendous manners, not their relatives' social rank - do we recognize the clues that should have alerted Elizabeth (and the reader) to the truth of the matter.
The Prince is an equal-level offender against aristocracy as a whole (which is a given, considering it's widely considered to be satire). According to chapter 9, nobles are mainly interested in maintaining their position and oppressing those underneath them to keep the status quo, whereas the common people mainly want not to be oppressed by the nobles. It also warns that a prince can never maintain the support of the noble class by acting honourably and just.
The Prisoner of Zenda has Prince Michael, the Duke of Strelsau, as the main antagonist. Michael falls firmly into the Bastard Bastard category (his parents were technically married, but since his mother was a commoner, he is only a prince because people are too polite to rub his face in it), and his duchy (which is ruled from the capital, no less) was a creation of his father's hoping that being the second-most powerful noble in the kingdom would soothe his anger at being passed over for the throne in favor of his younger half-brother Rudolf (it didn't)
Rachel Griffin: In The Raven, the Elf, and Rachel, Rachel notices that many Knights of Walpurgis come from noble families with dicey reputations.
The Red Vixen Adventures: Countess Highglider, the Big Bad. The protagonists, House Darktail, are minor nobles in vassalage to her, some years before the series her son married Sallivera Darktail and proved to be horribly abusive to her, getting locked up in an insane asylum after gouging her eye out. The Countess blamed the Darktails and started sabotaging their district's infrastructure and hiring pirates to raid their shipping routes. Subverted when the country's ruling Council of Countesses strips Highglider of her title and awards it to Salli's mother.
The Reynard Cycle: Played fairly straight in Reynard the Fox, which features Duke Nobel and Count Bricemer as Reynard's enemies (and the Countess Persephone as the exception.)
The Rifter: Played straight. The aristocracy are rapacious and repressive toward the common people; the one decent person among them that we meet, Joulen, has been away with the army in the north for years, and John reflects that the simple life had done him good. Lady Bousim, exiled in the north, turns out to be a very good friend to Laurie and Bill, although we are told that before, in the south, she had taken a series of lovers without caring that her husband would have them all executed.
The Saltwater Chronicles: The War King Mar Ketwan is a major villain, but even the "good" nobility like Queen Two Rabbit have done some messed up things. Two Rabbit regularly threatens to cut off fingers of people who annoy her, though it's unclear if this is an empty threat or not.
Scaramouche: The Marquis de La Tour d'Azyr is a ruthless, manipulative killer.
The Secret Texts by Holly Lisle has the Sabirs and their rivaling house. Anwyn, Andrew, and Crispin Sabir, in particular, are nasty, nasty individuals, including the brutal murder of one of their own guards while raping one of the daughters of their rivals. You know, until Crispin hits woobie status with the realization that the love of his life is dead, his brother is a traitorous snake, and the only woman he can ever love is his daughter.
In A Scholar of Magics, the Earl of Bridgewater is the seemingly helpful authority figure who turns out to have been behind the whole thing.
In Shadow of the Conqueror, before the Dawn Empire, Hamahra was ruled by an aristocracy evil enough to murder Daylen's entire family after he started a revolution against them.
The Silence of the Lambs: Count Hannibal Lecter VIII — you heard me, this count eats people. His title is only added in the books, however.
Slayers: Marchioness Gioconda of Slayers REVOLUTION is a mid-season villainess dabbling in creating and selling prototype magical weapons. One of her wares, a Zanaffar Armor, goes out of control and devours her, turning into the season's ultimate villain, Beast Zanaffar.
Plenty of people call themselves Kings or Queens (with varying degrees of legitimacy) and many of these people are hard to pin down morally. Still, we have a few shining examples such as Aerys II, a.k.a. The Mad King who was a sadistic nutso that ravaged the kingdom so badly and antagonized so many royal houses that he all but destroyed the future of the Targaryen dynasty. Joffrey I also gets special mention, being only slightly less bad than Aerys due to his relatively limited scope of influence at the time. Robert toes the line but was more incompetent and oblivious than malicious or cruel (though he caused his share of the suffering by failing to do the right things when it mattered). Stannis has a reputation as an Evil Overlord, but shows Hidden Depths and goes through Character Development which means he would probably make a good and progressive King. His younger brother Renly has a good image but is a vain schemer who intended to kill Stannis and usurp the throne. On the flip side, the only real evil queen we've seen thus far is Cersei; Daenerys' enemies have given her this reputation as well, though it's (mostly) base slander. Historically, there are other examples such as Visenya, who may have poisoned her stepson/nephew Aenys so her monstrous son Maegor the Cruel could succeed.
The series brings us "great lords" and "bannermen", who can be absolutely horrifying. If there is one lesson to be taken from the series, it's that feudal society sucks for everyone except the ones at the top. The vast majority of nobles in the series care only about themselves and their family, and the common folk is at best worth considering because they are cheap labor, but usually considered an afterthought. Even the series' more benevolent nobles, namely the Starks, care more about honor and nobility than they care about the smallfolk. The peasantry may not be suffering directly under "honorable" nobility, but things aren't changing for the better, either. A specific example is the nobility during the reign of Aegon V. Aegon was one of very few kings in Westeros who considered the smallfolk worthy of consideration and maybe getting slightly better lives. During his rule, he instigated several reforms meant to improve the condition of the working class, such as labor laws, but this made him immensely unpopular among the nobles. Even when he attempted to appeal to Pragmatic Villainy, pointing out that well-fed and rested workers work harder and are less likely to rebel than slaves-in-all-but-name, the nobility couldn't see beyond their immediate gains, and all of his reforms were rolled back after his death.
Spectral Shadows both plays this straight and subverts it, mainly in Serial 11. A lot of the Towns' Ruling Family are rotten, corrupt, or otherwise self-serving people. There are a few notable inversions though, namely Sir Jon and Miss Sonny, the King and Queen of Suburbia, respectively.
The Stormlight Archive: The lighteyes have gotten a little power-mad over the centuries, which tends to drown out the ones who actually are honorable.
Stravaganza: Duke Niccolo di Chimici series is the main villain of the first three books. On the other hand, the Duchessa of Bellezza is good.
In Sword Art Online, the Underworld has a Fantastic Caste System with nobles of various ranks, and the nobles tend to be rather corrupt. The nobles were originally intended to train in the sword to protect the human realms, but in practice, they hide in their lands, having forgotten their duty to the common people. There are some exceptions, mostly among the lower-ranking nobles(some of whom are practically no different than commoners), but there are also those who are even worse than the norm and horrifically abuse the common people in ways that are technically allowed by the Taboo Index.
In Sword Princess Altina pretty much all the aristocrats are evil or heavily compromised. Most of them are noted to see looking down on commoners as benign an activity as sampling fine wine, that is until the commoners get angry and take up arms. In addition, they are under the delusion that excessive conspicuous consumption would "make the citizens proud." Regis points out that in the capital full of nobles, that may be true, but in the outskirts and near the borders where commoners struggle very hard just to get enough to eat (never mind having to worry about enemy armies), this only serves to breed resentment. Altina very wisely listens to his council.
A Tale of Two Cities: The Marquis is a classic example of the evil marquis. His carriage runs a child down and not only does he give the grieving family a single coin as compensation but is also more worried about the health of the horse who trampled him than the boy himself.
The Talisman: Most aristocrats in the Territories are either evil or cowed into submission. The worst is Morgan of Orris and those working directly for him.
The Tough Guide to Fantasyland: A primary feature of any Bad land with Aristocratic Feudalists. They will be occupied with abusing the peasantry, alongside intrigues against each other in the royal court. The peasants may well revolt during the Tour because of this oppression.
Twig: The major appearance of the Baron of Richmond is when a spy in the Baron's country's military comes with a warning that the army they're fighting has primordial monsters, and reminds him that in the event of primordials standing orders are to immediately escalate to overwhelming firepower. The Baron slices out the spy's eye and berates him for being too weak to fight the primordials himself. The Baron's personal city, Warrick, is an outwardly picturesque town where the firstborn child is taken from every family, turned into monsters programmed to kill anyone who disturbs the town's peace, and then given back, with orders to the families to take care of the monsters or be given to the Baron's sisters.
Vampire Academy: There are notable exceptions, but the royals tend to be selfish and spoiled. Non-royal Moroi and dhampirs tend to suffer at their hands.
Vampire Hunter D: L Count Magnus Lee, obviously inspired by Dracula (and Christopher Lee). Also, the vampires in this world are called Nobles or Aristocrats.
In Vorkosigan Saga, all of the barons of Jackson's Whole are evil: the worst is Baron Ryoval, who is in the sexual slavery business and is an enthusiastic practitioner of Cold-Blooded Torture, employing a number of technicians to aid his hobby; his brother, Baron Fell, is a notorious arms dealer specializing in biological weapons; and Baron Bharaputra has a genetics clinic specializing in a procedure for the wealthy but aged, in which a young clone of them is produced, and then the clone's brain is ripped out and the original person's implanted instead). However, Jacksonian barons aren't really aristocrats: they are at best unscrupulous plutocrats and at worst, mob kingpins. The hat of Jackson's Whole is "capitalism gone very, very bad".
The Woman in White: Sir Percival Glyde, who is absolutely evil and has the disfiguring scar to prove it. The novel also gives us the Manipulative Bastard Count Fosco, who is presented as essentially Don Corleone for 19th century England.
Young Bond: Count Ugo Carifex from Blood Fever, who plans to drive Europe into another World War and become its shadow ruler.
Young Sherlock Holmes: Baron Maupertuis, the Big Bad of Death Cloud, is an Evil Cripple, who is driven by a fanatical hatred of England and who plans to murder hundreds of thousands of British troops.
Almost all literary vampires of the 19th century were aristocrats, as demonstrated by the already mentioned Lord Ruthven of John Polidori's The Vampyre, Sir Francis Varney of Varney the Vampire, Countess Carmilla Karnstein, and Count Dracula. This trope has a modern successor — after the privileges of the nobility have been abolished and the elites are now comprised of a wealthy bourgeois upper-class, vampires now tend to be filthy rich rather than aristocratic. Both tropes play on the symbolic connection between literal blood-sucking and the parasitic way of life of an (assumed) real-life idle class that does not support itself by its own efforts, but by exploiting other people.
" by P. G. Wodehouse, wherein one Sir Jasper Murgleshaw, at heart a philanthropist, feels obliged to kidnap, rob, and poison people simply because he's a baronet. Then it's discovered that he has no legal claim to the title, and he promptly becomes a Sunday School teacher.
Lawful Good and, for that matter, absolutely hates his title.