RuGaard from E. E. Knight's Age of Fire series is a partial subversion of this trope. While he's an Evil Overlord, he's a dragon, carries a good approval rating from most of his underlings — even his personal slaves Rayg, Rhea and Fourfang, with him intervening to save them more than once — practices Equal-Opportunity Evil, shows most of the traits we'd expect of a fantasy hero, and oh, plans to subjugate all the hominids in the world. But it's all justified, you see, because not a single free hominid he's encountered has ever been vaguely nice to him.
Age of Fire has several other evil overlords — Thane Hammer (a feudal lord of northern Hypatia, who united his neighbors through force and murder), Gobold Fangbreaker (king of the Wheel of Fire dwarves, who rules with an iron fist and murdered the dragon protagonists' parents), and the Red Queen (ruler of Ghioz, who tries to conquer the whole world).
Animorphs. Two words: Visser Three. The first Visser One might also qualify, as things she does are undeniably ruthlessly evil, but they're more motivated by her military goals than an inherently malicious personality.
Anno Dracula by Kim Newman showed an Alternate History timeline where the Count Dracula survived the events of the novel and managed to take over the British Empire by turning Queen Victoria into his bride/puppet as the tyrannical Prince-Consort, he rules over England as an repressive police state where dissenters are executed without trial... Through impalement.
The Red King in Baltimore is an Vampire Monarch who unleashes a campaign of terror upon the world after being woken from his slumber during World War I and by 1925 establishes the Red Kingdom, an empire that covers all of Eastern Europe and Asia, ruling over not just vampires but also witches, demons and evil human worshipers that commit random acts of cruelty in his name. Not even an alliance between Germany, USA, England, France and Italy can hope to win against the Red King.
Bazil Broketail: The Masters of Padmasa are five immortal evil wizards living in their underground citadel who direct their forces to take over the world, as the books' main villains.
The Black Company novels by Glen Cook has a Sorcerous Overlord collection, sometimes subverting this back and forth. The main Evil Overlord of the books is an Overlady. She's the wife of the former Evil Overlord, the Dominator, but after their time together as Sealed Evil in a Can she left and made sure he's kept in. Because he's too evil, too powerful and hey, it was only a political marriage. This gets twisted in more and more ways from there.
Giles becomes this in the Buffy tie-in serial novel The Lost Slayer after getting vamped. He's king of Sunnydale and some of the rest of southern California.
The Chronicles of Narnia: Although the Evil Overlord is usually both male and associated with black (hence, Dark Lord), C. S. Lewis' The Lion, The Witch, and the Wardrobe presented a female associated with whiteness, the White Witch, as Narnia's evil ruler. The Magician's Nephew revealed that she had been Empress of Charn and destroyed all the life in her original world rather than lose to her sister. And in The Silver Chair, the Lady of the Green Kirtle is queen of Underland and out to conquer Narnia. Human Evil Overlords include the Tisroc of Calormen in The Horse and his Boy and Caspian's Uncle Miraz in Prince Caspian.
Arawn the Death Lord of Annuvin from The Chronicles of Prydain. He actually started out in the series backstory as the right-hand man to the previous Dark Lord, Queen Achren, but deposed her. It is worth noting that Arawn subverts certain aspects of this trope. Rather than being an unfathomably powerful opponent, he is portrayed as a cunning trickster who corrupts mortals through illusion and deceit. In combat, he proves to actually be quite weak, relying on his army of Nigh-Invulnerable undead minions to protect him. And even they're just his elites that he can trust; his serious attempts to conquer Prydain have always relied on the armies of petty rulers who are supposed to be allied to the good guys but have turned traitor to do the heavy lifting.
Lord Foul. He wears black, has glowing red eyes, lives in Mordor, wants to destroy the world, is a master of The Plan and commands several armies of evil mutants- at least in the first trilogy. In the second trilogy, he has more or less obtained domination of the Land but sticks to the shadows, ruling it indirectly through his proxies the Clave. In the final quadrilogy, he's given up on rulership entirely and is just focused on destroying the Land outright.
The Gadhi from the same series, however, is a Deconstruction of the trope. He's a brutal tyrant, to be sure, but he and his family only hold their throne through an alliance with an Evil Sorcerer, and the Gaddhi is well aware that he needs to stay in said sorcerer's good graces or else he'll end up overlord of nothing. The end result is that he has very little actual power — even his own royal harem defer to Kasreyn first.
The Shadow Lord from Emily Rodda's series Deltora Quest.
Dis Acedia: most of the Edge Kings, the rulers of Dis, qualify (and fight each others to become the one sole overlord). The protagonist eventually becomes an anti-heroic one.
The Evil Lord Harry Dread from The Last Hero parodies many tropes of the Evil Overlord: He got started with a Shed of Evil, hires guards so stupid they have trouble remembering their names, and ends up briefly allying with the Silver Horde, but then betrays them because, hey, Harry's the bad guy, it's what he does. Also, he hires his guards to be stupid so that the heroes can escape from his dungeons, and leaves chests full of armour and weapons about his Lairs because that's how the game is played. The heroes, in return, refrain from killing Harry out of hand and don't look too hard for the inevitable secret escape routes. Both he and the Silver Horde are rather unhappy about this new generation of heroes and villains who make an effort to be competent and thorough at their respective alignments. Heroes who actually capture and kill villains, villains who actually rule with an iron fist, etc.
Lord Vetinari from the same series has all the trappings of an Evil Overlord, except that he happens to be a Reasonable Authority Figure who is pragmatic enough to know that evil doesn't pay. His only acts of public villainy involve having all mime artists tortured to death via scorpion pit, and nailing avant-guard artists (with a suspicious similarity to Tracey Emin) to their own creations via the earlobes. That only made him more popular.
The Divine Comedy: Despotic kings are so common in the world that Solomon is justly be said to be the wisest man alive for managing to maintain monarchy and morality in one man. For a few examples:
As part of his sick mockery of the Heavenly Lord, the Devil takes the title of Emperor of Hell to signify his leadership of the Fallen Angels and his role in causing each suffering. Instead of a castle, he has the darkest pit in the universe; instead of towers, his "castle" surrounded by chained giants; and instead of moats, his home is guarded by ten ditches filled with the soul of every liar in history.
In Purgatorio XX, three kings named Charles (Charles I, Charles II, and Charles of Valois) are prophesied to become richer in evil than any before them for crimes such as the murder of St. Thomas, the exploitation of Florence, the enslavement of Valois' own daughter. Yet all these horrors pale in comparison to what Hugh Capet sees King Phillip IV committing. For corrupting the papacy to meet his own political ends, Philip earns the title of "New Pilate" in accordance with his attack on the Body of Christ.
Paul Atreides of Dune Messiah is somewhat of a deconstruction/subversion of the trope. He is worshiped as a god by his Fremen legions whose jihad has spread their religion across the universe at the expense of billions of people, the once Proud Warrior Race is now rich and corrupt, and in comparison the Shaddam IV who he overthrew seems like a saint. However, none of this was Paul's intention. A group of overzealous Fremen started the religion and jihad and after 12 years it escalated to the point of Paul being a figurehead without any power to stop it, leading to the irony of being a powerful emperor who commands his subjects yet a powerless god who can't stop his worshipers. He also still manages to be the hero of the story because almost all of his enemies want to overthrow him for their own selfish purposes rather than stop the jihad. Paul was on top of this to begin with mostly because as enough of a prophet to see the big war is coming (back in the first book), he tried to somewhat limit the inevitable destruction by taking control.
His son, Leto II, the God-Emperor, is another deconstructive example. He rules over territories from several galaxies with an iron fist, demands that his subjects worship him, commands an army of savage female fanatics, and uses his monopoly over the spice to prevent any challenge to his authority. What only he knows, however, is that he is using his reign as a means to free humanity from prescient rulers like himself and to ensure that humanity follows his "Golden Path" - the path away from extinction. In short, his brutality and oppression are intended to make humanity chafe under his rule, such that his death will be followed by a mass exodus that scatters the human race so far that they will never all fall under the sway of someone such as him ever again. His contemporaries think he is simply a power hungry despot.
Goblin Slayer: Every decade an Demon Lord raises from the pits of Hell to destroy the cities of Man and overthrow the Gods. They represent an cyclical existential threat to the setting but here is the twist: the Demon Lord is an Villain of Another Story since Goblin Slayer and his associates are too focused in exterminating goblins to focus on him, as such, its the job of other adventurers to handle the Demon Lord and his generals.
Gone: Caine Soren aspires to be one, but is deposed soon into book one. In book four, he succeeds.
Lord Voldemort from the Harry Potter series. He was deposed before the start of the series and only eventually regains Overlord status, operating more as a terrorist and cult leader for much of the books, but people still recognize him as one, including his followers using the term Dark Lord. He ends up coming back and basically taking over the Wizarding World of Britain. Of course, just declaring himself Lord in front of the entire wizarding community would be too blatant, so he still operates as The Man Behind the Man with the corrupted Minister of Magic as his puppet. Gellert Grindewald was one, before he was defeated by Albus Dumbledore.
Galbatorix in the The Inheritance Cycle was a fallen Dragon Rider who rose up against the others and destroyed his order, now rules as the King of Alagaesia by right of conquest.
Capricorn from The Inkworld Trilogy is a cookie-cutter example of this trope. He's also something of a capricious ganglord punk. Depends what you take from it.
The Last Leprechaun King was a major threat to the Fae Realms, Connie managing to save the Fae Realms from his curse on one of her adventures by throwing all but a single coin from his treasure hoard into a volcano. She would later bribe the oracle Scurm with it in The Last Adventure of Constance Verity to locate her Fairy Godmother.
Several flavors of this (both played straight and subverted or deconstructed) appear in the Malazan Book of the Fallen:
In the setting's prehistory, the Jaghut were a race of precursors who were immensely powerful, nigh-immortal mages, but generally peaceful hermits. The exceptions to this rule were Jaghut Tyrants, who used their vast powers to enslave other races and rule as god-kings. The Tyrants caused such damage that another race of precursors, the T'lan Imass, swore an eternal oath to wipe out the Jaghut to prevent any more tyrants arising. Though Tyrants are referenced many times throughout the series, the only one who is named is Raest.
Kallor, the High King, was the ruler of one of the first human empires, and his rule was so brutal and oppressive that his own subjects colony-dropped a god on him to try and get rid of him. Didn't work. Finally, he destroyed his own empire to prevent the rest of the pantheon from taking it away from him, and for his troubles got cursed to live forever but to never ascend to godhood himself and to ultimately fail at everything he attempts. He's still around at the time of the main series, and still calls himself the High King, though it's been centuries since he actually ruled anything.
The Pannion Seer is God-Emperor of the theocratic empire called the Pannion Domin, which is essentially an attempt to create Mordor on an industrial scale. The Domin is viciously aggressive, works its citizens brutally and keeps a horde of peasants starved into madness and cannibalism to supplement its regular army. It's noted that the Domin is entirely dead in its core regions and alive only at the fringes, and therefore it must expand constantly. The Seer actually seems to encourage this, as if inflicting suffering on his people is actually more important than running a functional nation. He's also one of the last surviving Jaghut in a human disguise, making him a Jaghut Tyrant.
Rhulad Sengar, the Emperor of the Thousand Deaths, is a deconstruction. He never wanted to be an evil overlord, and he does try to rule well, but his powers come from a cursed sword that brings him back whenever he dies but wears away at his sanity and induces Body Horror every time. As he becomes progressively insane Rhulad becomes progressively brutal and paranoid, and then finally reaches a point where he's so out of it he can't rule at all, leaving his Evil Chancellor and the Secret Police to actually carry out his tyrannical regime in his name.
The city-state of Darujhistan was once ruled by a succession of powerful Sorcerous Overlords called the Tyrant Kings, who made it the capital of a continent-spanning empire. The present Darujhistan threw out the last Tyrant long ago, and is now the closest thing the setting has to a republic. Orb, Scepter, Throne reveals that the Tyrant Kings were actually one Tyrant King who hopped from body to body, and in that novel he comes back for another try.
The Malazan Empire's founder Kellanved and current ruler Laseen are both subversions. Kellanved was a mage first and emperor second who saw ruling as being a stepping stone to other, more esoteric forms of power which he acquired when he ascended to become the god Shadowthrone while Laseen is perceived as villainous by many of the protagonists but is genuinely trying to do what is best for her empire and isn't that much worse than any other rulers in the setting.
Maoyu averts this trope, and revolves around the deconstruction and reconstruction of the high fantasy world setting. The "Maou" (demon king) is actually a Cute Bookworm who is in no way evil (or male), and secretly allies with the destined "Yuusha" (hero) to stop the war between humans and monsters via economical and political means.
Parodied in Something M.Y.T.H. Inc., in which the common people of Possiltom think Skeeve is an example of this trope because he consorts with (friendly and likeable) demons, keeps a (goofy pet) dragon, and has (out of dire necessity) raised their taxes.
In the New Jedi Order, the absolute ruler of the Yuuzhan Vong actually has "Supreme Overlord" as his main title. It turns out he's just a mindless shell Onimi uses to act as his public face.
Big Brother from Nineteen Eighty-Four is very much the idea of the Evil Overlord regardless of whether there's an actual human being behind it or not, or whether or not that person is the "original" if they do exist. However, Big Brother could possibly be a deconstruction, since he does not establish absolute rule through simple displays of power, but surgical manipulation of information and brainwashing his subjects to love him and consider serving the state their only goal in life.
The usurper Waldo in One for the Morning Glory: he conquered the kingdom of Overhill and personally murdered two infant members of the royal family when it was massacred; turned Overhill into a wasteland; and set out to conquer the next kingdom with evil magic, undead, and goblin allies.
Overlord (2012) has the main character, a gamer who is trapped in an MMO world as his character Momonga, who promptly christens himself after the name of his guild, Ainz Ooal Gown, and seeks to take over the world with his incredible magical power. Although Ainz at first he isn't this trope, he is getting there as the novels go on. By the time of Volume 9, he has officially become one.
The Reynard Cycle: The setting of this series was once ruled by one called Stormbringer, the Demon King. The plot of the first book revolves around the recovery of a living gem that he wore in his iron crown.
Susebron the God-King in Warbreaker is built up as a terrible, possibly insane Evil Overlord but is actually a very nice (and very naive) guy who is controlled by his Well-Intentioned Extremist priests and his Not-So-Harmless Villain secretary.
From the same book's backstory, Kalad was a legendary Awakener and warlord who was responsible for a cataclysmic conflict called the Manywar that was only ended thanks to the efforts of Peacegiver. Except, that's not quite true- Kalad and Peacegiver were the same man. Kalad became sickened by what he'd unleashed, made peace, hid his undead army away, and abdicated his throne. He currently wanders the world calling himself Vasher, trying to keep anyone else from making the mistakes he did- while safeguarding his Artifact of Doom, Nightblood, from the wrong hands.
The Stormlight Archive: The Alethi people are known around the world to be deadly warriors and brutal conquerors, and in his youth Dalinar Kholin helped his brother beat the rest of their kingdom into submission, and now seems to be taking the throne from his Nephew. We see his point of view and know that he really is just doing his best to bring everyone together in the face of The True Desolation, but he frequently notes that the other nations of the world justifiably sees him as a dangerous, conquering warlord and he has to spend a great deal of time proving he really is just trying to help.
Belial from The Salvation War: Armageddon. Interesting subversion: He's not the guy in charge, in fact he's a nobody in Old Nick's court. So much so that the destruction of Sodom and Gomorrah were considered highly amusing party tricks — and he's just there as the court jester. Turns out, however, that they're not quite "party tricks" after all...
In Liliana Bodoc's The Saga of the Borderlands, Misaianes the Son of Death is a good example. He is actually The Eternal Hatred that has taken physical form, which makes it literally an Eldritch Abomination. He has started a war that has lasted more than 500 years, and after seizing almost the entire continent of The Ancient Lands, he rules, along with a small elite of magicians and nobles, over millions of slaves who in many cases cannot even possess a name. And now he intends to extend his domain to The Fertile Lands ...
The Shahnameh has Zahhak, who might be considered the prototypical example of this trope: A former human who was tempted into evil by the God of Evil Ahriman, becoming a cursed demonic tyrant whose reign lasts for a thousand years. He also has The Chosen One in the form of Freydun who is destined to head a rebellion and seal him within a volcano till the end of time.
Brona, an undead lord who manipulates various races at various times in his bid for Global Domination.
The Ildatch, a sentient book of pure evil that served as The Man Behind the Man (or the sentient object behind the man) for Brona, being destroyed some three generations after him.
The Dagda Mor and his eventual heir, Tael Riverine, who lord over an evil dimension filled with creatures sealed away long ago who merely seek freedom, though freedom entails overrunning the world with monsters.
A Song of Ice and Fire: Like many tropes that the series uses, it's usually deconstructed. An infamously cruel king (or someone who merely has that reputation, deserved or not) is likely to end up with no allies or will even see his once-faithful bannermen rise up against him when he kicks one puppy too many. They also generally lack the sorcerous powers typically associated with a proper evil overlord, though some of the worst members of the Targaryan dynasty certainly had dragons and a form of Greek Fire to back their attempts at despotism or tyranny up with.
Stannis Baratheon seems like this at first glance. He is ruthless and fearsome and his ascension to the throne is seen as a sign of the Apocalypse (because he lacks charisma and is a Principles Zealot), lives in the exotic Island fortress of Dragonstone (which he never wanted and suspects his appointment to its lordship is tantamount to exile), consorts with criminals and mercenaries (his vassals don't have enough manpower), has an Evil Sorcerer in his service (who believes he is the Messiah of her faith), murders his brother with dark magic (they were trying to usurp rule and intended to kill Stannis), and is driven to be king by any means (even though he doesn't want to but its his duty to do so and by the law he should technically be King, though because most of the Seven Kingdoms doesn't believe his "nephew" is really illegitimate he is seen as an Evil Uncle). He is even called a "Dark Lord" at Joffrey's wedding.
And then there are characters who are this trope even at second glance. Meet Euron "Crow's Eye" Greyjoy, the pirate king. Raised in a culture that glorifies rape and piracy, who worship a nigh-Cthulhu, and they either distrust, despise, or outright fear him. Went into exile after raping (or seducing) his sister-in-law, and proceeded to sail around the world pillaging and picking up various warlocks and barbarians. Has a posh for black. Suspected of murdering his brother Balon so he could take the Seastone Chair, even though Balon wanted his daughter to succeed him. And his current plan is to wake a dragon and conquer all of Westeros. There are even theories he is in league with the Others, planning to bring down the Wall and become their ruler.
Roose Bolton. Rules a terrifying fortress in the Grim Up North? Check. (It’s called the Dreadfort.) Tortures and abuses his subjects? Check. Makes and betrays allies when doing so may benefit him? Check. Makes pink a highly intimidating colour just by the association with rumours of torture (the ancient Boltons liked to flay their enemies alive, and anyways black is too easy). Check. Is Stupid Evil enough to incite rebellions or make enemies of just lords? Uh... well... no, actually. His son, Ramsay Bolton, on the other hand.....
Joffrey Baratheon subverts this, as though he is technically King he is really just The Caligula and incapable of really running the Seven Kingdoms. His grandfather on both sides Lord Tywin Lannister, the Dragon-in-Chief of the Lannister regime may be seen as this. He's the scary head of House Lannister, one of the most powerful families in Westeros, and is a ruthless and powerful commander who even has his own Villain Song "The Rains of Castamere", on how he wiped out a family that rebelled against the Lannisters.
Tywin's daughter Queen Cersei tries to emulate him after her youngest brother kills Tywin. Cersei is certainly cruel and tyrannical, however she is clearly not as effective as Tywin, her paranoia, grasping obsession with power, and fears of losing her children dominate proceedings, along with eroding her mental stability, and leaving the Lannister regime unstable.
Aerys II, very much The Caligula. He began decent enough, if vain, eccentric, and sleazy, but over time became more paranoid and cruel. Eventually he delighted in burning people alive, even murdering one of his most powerful Lords, Rickard Stark, and strangling their oldest son Brandon while they were Forced to Watch. However, he serves as a Deconstruction, as his cruelty and Stupid Evil actions led to a huge rebellion against him, with very few powerful figures willing to help him. His constant unpleasantness towards his former Hypercompetent Sidekick Tywin Lannister leads to them becoming The Starscream and turning against him when Robert's Rebellion begins winning. Out of spite, Aerys decided to set off wildfire beneath King's Landing, killing Tywin, his troops, and half a million people, leading to a Bodyguard Betrayal from Jaime Lannister, who killed him and saved the city.
Historically, more then two centuries before the books begin, was Maegor the Cruel. He killed two of his nephews to help his usurpation of the Iron Throne after his brother Aenys' death, murdered some of his wives, and forced one of his nieces to marry him. He has a reputation as the cruelest King to ever sit the Iron Throne because of his numerous atrocities in his war against the Faith. However, his cruelty eventually led to the Seven Kingdoms uniting behind Aenys' last son, and Maegor died mysteriously on the Iron Throne, though many believe he killed himself.
When the Seven Kingdoms were Seven Kingdoms, there was Harren "the Black" of House Hoare, King of the Rivers and Isles. His grandfather was a King of the Iron Islands who conquered the Riverlands. Harren was notorious for his cruelty and brutality, and was the most feared of the Kings in Westeros of his time. He spent most of his reign trying to built the biggest castle in Westeros, Harrenhal, draining his Kingdom of wealth and resources, and having quite probably thousands work themselves to death in the process. Harren was so hated that, when Aegon The Conqueror began his conquest of the Riverlands, the River Lords (including the Lords Bracken and Blackwood) quickly joined Aegon, who then unleashed his dragon on Harrenhal, ending House Hoare. Let's underscore that: the chronically and systemically divided Riverlanders actually pulled together for once in their history to welcome an outside faction to use nukes against House Hoare.
The Space Trilogy: From Perelandra on, the Bent One is referred to as the Dark Lord of Earth. He rules not by force, but through turning the hearts of men away from their original devotion to Maleldil and towards self-love so extreme it becomes hatred. With the armies of invisible eldila serving him, the minds of Earth must be extremely dedicated to avoid being dominated by the armies of the Black Archon.
Randall Flagg in Stephen King's The Stand. Following civilization's downfall, Flagg emerges as the dictator of Las Vegas where people flock under him and he keeps them in line through fear. Flagg is also the ultimate evil, a demon in the shape of a man whose presence brings calamity wherever he goes. It should be no surprise that King based him on Sauron.
Khan, along with the rest of the superhumans in Star Trek: The Eugenics Wars carve out their empires in unstable regions like the Middle East, Eastern Europe and Africa. Khan's empire is the largest, encompassing much of Asia. At first he tries to be benevolent, and succeeds. Over time as the battles against the other superhumans and Gary Seven takes more time, attention and resources, he has to come down harder and harder on any trouble until eventually he's just another despot.
Completely subverted in Jacqueline Carey's duology The Sundering which is told from the viewpoint of the Evil Overlord. Although he suffers from chronically bad press it turns out that he and his subjects just want to be left alone and it is the god of the Elves who is trying to throw down.
Darken Rahl and Emperor Jagang in The Sword of Truth series by Terry Goodkind. Rahl is more archetypal since his minions know he's evil but still follow him out of loyalty, while Jagang and his empire think they're right.
The Internet story Tales of Lokaria has the Black Master: a man who has lived nearly a thousand years and rules over much of the known world. And there's his hidden Mind Rape powers. His castle is constantly upgraded with the latest technology. He then purposefully leaves openings to let rebels and heroes in to kill them. He does have a 0% Approval Rating, but his Legion of Terror is very well trained and loyal. And he's kinder than the elfin Kingdom, led by Tidal, despite what people say. He also is extremely cunning.
His team is as follows. His Dragon, Dracon (no less!) is an ancient half-elf who is immortal and extremely powerful, and his best friend. Another member was mind-raped into submission. The Brute (the Mook Captain) is entirely loyal and very intelligent. The Mad Scientist has yet to be introduced, but can produce technology to warp reality and use magic.
Astaroth is a subversion. While he effectively rules the world, he mostly delegates that to the four demon kings (of which Prusias is one), and doesn't do any ruling at all once the demon kings lose faith in him. It turns out that his true ambition is partly this trope: he wants to rule the world as its Creator and doesn't give a damn about its residents: when he realizes his dream is impossible because the Book of Thoth won't let an Eldritch Abomination like him create life, he decides to kill everybody by feeding them to his creators, the Starving Gods, and making a new universe out of the leftovers that he can rule over.
In The Silmarillion, Sauron was merely The Dragon to Morgoth, the Big Bad. Morgoth himself fits a lot of criteria of the Evil Overlord mixed with a PhysicalGod of Evil, but supplemental material paints a picture of someone less interested in power in the here and now and more in destroying the world because it's not his creation. Tolkien even seemed to write in "Morgoth's Ring" that Sauron ended up more powerful then Morgoth as he didn't squander his power.
The Tough Guide to Fantasyland: The Dark Lord, one of whom exists for every Tour trying to destroy everything. However, they can be defeated fairly easily by Tourists near the finale. There are no Dark Ladies, for it seems the Management finds them less sinister.
Trapped on Draconica: Gothon tried to avert this trope (because his dad was evil) but his single-minded focus on his Evil Plan turned him into one.
The Big Bad in theTygrine Catseries is the Suzerain of the Sa Mau, occasionally referred to as the Cat Lord. He leads a dynasty of cats who exemplify their species' predatory instincts, with the goal of taking over the world by wiping out the rival Abyssinia Tygrine dynasty, guardians of the souls of every cat on Earth. He also wishes to punish every cat who benefits from interaction with humans in some way. He resides in an underground palace and has powerful occult abilities.
Archmage Mizzamir certainly qualifies. An ageless elven warlock hiding away in his tower stronghold working to impede and halt the progress of the warriors trying to save the world, watching with distant unseen eyes, having conquered the world and molding it to his image after winning the final battle between Good and Evil a hundred and fifty years ago. The twist is that Mizzamir was actually on the side of good, and his attempts to mold the world to his wishes involves slowly turning it into a sugarbowl where evil-doers have no choice but to be Good. The group of heroes are actually a band of villains trying to undermine a Virtuous Overlord.
Although he's long dead and gone by the time of the book, the Dark King was clearly this. Few details are given, but he'd waged war on the forces of Good, with his armies capturing the last elven city plus many human ones until his defeat by the Six Heroes.
A Woman's Work: Queen Arrabel is the ruthless monarch of an empire, enough that she'll even set up her own very incompetent son to get killed, yet is also smart and realizes everyone loathing you will undo any ruler. Thus, she is ruthless though also generous with her subjects and even likes that the more competent heir to a conquered kingdom could succeed her after killing her own foolish son, explicitly dodging everything on the Evil Overlord List.
Worlds of Shadow: Shadow, the mysterious ruler of Faerie (aside from small areas that are still free), whose rule is marked by people in terror, incredibly harsh punishments for minor offenses, creating monsters for use against enemies and a desire for world (then eventually interdimensional) domination.
. Interesting subversion: He's not the guy in charge, in fact he's a nobody in Old Nick's court. So much so that the destruction of Sodom and Gomorrah were considered highly amusing party tricks — and he's just there as the court jester. Turns out, however, that they're not quite "party tricks" after all...