"People of Earth! I am Darkseid, Lord of Apokolips! Here is your savior, cowed and broken. I have crushed him as easily as I have crushed all who have dared to oppose me throughout the Cosmos. I am power unlike any you have known: absolute, infinite, and unrelenting. You have no choice but to prepare for a long dark future as my subjects—and my slaves."
Sosuke Aizen is a narcissistic sociopath with a god complex, who manipulates and betrays everyone who trusts him and doesn't hesitate to leave even his closest associates Not Quite Dead on the floor. Fittingly, he rules his army of Arrancar from his enormous white palace of Las Noches.
The current Big Bad, Yhwach, is The Emperor of the Wandenreich, a hyper-militant organization of spiritually-aware humans known as Quincies. He's a brutal, intolerant autocrat primarily interested in causing as much discord, conflict, and death as possible in order to extend his lifespan, and he's perfectly willing to overlook - or even encourage - his Team Killer subordinates to perform Unfriendly Fire at their whim. He rules from his ice palace of Silbern, located in the Wandenreich city in a shadow realm (or Schatten Bereich) directly underneath the Soul Society. As a bonus, he's already conquered Hueco Mundo on the side, and often forces Arrancar to join his empire or face death.
InuYasha subverts the trope. Naraku does take over a castle but that's because he wants control over the people who serve the young lord whose body he's possessed. He kills everyone in the castle soon enough and focuses on building up enemies and destroying the bonds between people at every opportunity. He has absolutely no interest in taking over the world, however. He simply wants to twist all bonds.
Lelouch and Schneizel from Code Geass R2 are fighting for this position. Slightly subverted in that Lelouch appears to be one but pulls a Milliardo Peacecraft maneuver like in Mobile Suit Gundam Wing by dying a villain but uniting the world, while Schneizel acts all nice when it's been indicated he's the real deal. Having a father who promoted Social Darwinism means they may need something more to overshoot him...or not.
Judai Yuki of Yu-Gi-Oh! GX fits almost all of this trope's requirements (up to and including Spikes of Villainy) during his time as Haounote can be translated as "Supreme King", "Overlord" or "Hegemon", a merciless tyrant obsessed with the completion of a powerful card and with the elimination of all evil in the world — even if he must use heinous methods in order to do so. Brron, Mad King of Dark World, whom Judai displaced, counts as well.
Light Yagami or Kira becomes this in the second half of Death Note.
Queen Esmerelda of Dai Mahou Touge is the queen of the supposed Mary Suetopia Magical Land. She's also an massively evil being who issues slave labor for public transportation, ruthlessly dispatches with protesters and gained her position via slander and mudslinging against the previous rulers. The main character Punie is a Magical Girl Evil Overlord in training.
Science Ninja Team Gatchaman has Sosai X and Berg Katse.note Battle of the Planets has them as the Luminous One, Zoltar and Mala, while G-Force: Guardians of Space has them as Computor and Galactor. Katse wants to rule the world; X starts out that way, but midway through switches to wanting to destroy it. Katse goes for purple and a pointy-eared cowl and once fought Gatchaman to a standstill, while X is a blue flame with glowing eyes ensconced in a secret base in the Himalayas.
The DCU villain Darkseid embodiesnote and yes, literally "embodies"; he's the Anthropomorphic Personification of Tyranny virtually every aspect of this trope, on a cosmic scale. There's a reason he's the one quoted at the top of the page.
The Marvel Universe has the interdimensional entity Dormammu, who has less of a street cred than Darkseid, but is so ridiculously more powerful that he routinely beats up various cosmic entities through his own power, by far outranks all Marvel's known rulers of hell, and is worshipped as god in thousands of magical universes. His pleasant ambition is to slaughter and usurp all higher entities, conquer all life and afterlife, and turn all of existence into an eternal torture camp dedicated to his personal glory... He's essentially Marvel's most terrifying villain when you think about it, more akin to an Eldritch Abomination really, except being even more powerful... But then you remember that his head is on fire, and that he's usually severely downscaled to let anyone even have a shot at surviving.
Several Marvel villains fit this trope. Shuma-Gorath is an even more powerful demon than Dormammu, and all the Hel Lords those two are above are still this in their home turf, as is virtually any demon or evil Death God with their own realm. Doctor Doom qualifies for this trope, as does Loki and other arch-villains whenever they gain territory, or world domination as they often do for a time.
Talonhoof the Reviled was a more traditional example, being a brutal warlord who united the remnants of the Griffin Empire and Mongrellian Horde by force, enslaving and torturing any ponies in his territory, before launching a war of extermination against Equestria.
There's also Film Critique and several other ponies who got their hooves on one of the Shards of the Rainbow of Light from Patch's 7 Dreams/Nightmares Side Story, though the former is the only one we see in detail. He used the Shard to take over a city and rule it as one of these, complete with turning mares into his brainwashed harem. Incidentally, since the Shards are the source of their powers, most of these, including Film Critique, meet a Karmic Death shortly after Patch steals them.
The Psyche Master from Empath: The Luckiest Smurf, although it's played with as the only evil thing he ever did was take Empath away from Papa Smurf and raise him as a Psyche. (He's basically the series' Expy of the MCP from TRON.)
Lord Business in The LEGO Movie, who presides over a practically defined Dystopia as President Business, but is so theatrical with his outfit, his infinitely tall tower with his Think Tank, Kragle and hundreds of minions he's virtually melodramatic.
Films — Live-Action
Tim Curry's Lord of Darkness in Riddley Scott's Legend fits this to a T.
Most other Sith Lords in the Star Wars universe with a position of command of some sort fit this trope as well, notably Darth Vader and Count Dooku (two of Palpatine's apprentices). In the Star Wars Expanded Universe, we have Darth Revan, Darth Nihilus, Darth Malak, Darth Krayt, and many, many others.
The Lord Marshal of the Necromongers in The Chronicles of Riddick. The supreme ruler of a tyrannical death cult / conquering civilization of superhuman warriors, his goal is to subjugate and destroy every world in the cosmos and lead them to a promised land of darkness they call the Underverse, which he has visited in his pilgrimage. Outright supernatural himself, and he's got the look down pat◊.
In Queen of the Damned, vampire Queen Akasha's reign over Ancient Egypt with her consort King Enkil is inferred to have been insanely tyrannical. Marius notes that she nearly drank the world dry to satiate her bloodlust and she shows several visions to Lestat of random massacres of her subjects. Later on she feeds on hundreds of people and declares the resulting graveyard her new kingdom to a disturbed Lestat. In the climax she announces to the other Ancients that she wants to return the world to the way things were and reduce humanity to cattle.
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. 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.
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.
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 Genre Savvy enough to know that evil doesn't pay. His only act of public villainy was having all mime artists tortured to death via scorpion pit. That only made him more popular.
Lord Voldemort from the Harry Potter series. He was deposed before the start of the series and only eventually regains Overlord status, but people still recognize him as one, including his followers using the term Dark Lord.
Arawn the Death Lord of Annuvin from the Prydain Chronicles. 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.
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 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 Dangerously Genre Savvy.
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. The Dark Chick 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.
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.
Brandon Sanderson plays with this one in all his works:
Wyrn in Elantris is a straight example (so far as the audience can tell- his only onscreen appearance is a cameo).
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.
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...
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 Gadhi from the same series, however, is a Deconstruction of the trope.
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.
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.
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.
Big Brother from 1984 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.
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.
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 of creatures sealed away long ago who merely seek freedom, though freedom entails overrunning the world with monsters.
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.
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.
Stannis Baratheon of A Song of Ice and Fire seems like this at first glance. There are twists of course, to his character. 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 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) and is driven to be king by any means (even though he doesn't want to but its his duty to do so).
Chancellor Dongalor is a parody of this in Krod Mandoon and the Flaming Sword of Fire
Doctor Who has The Master (at his most successful) and Davros whenever the Daleks actually listen to him.
Lord Zedd of Mighty Morphin' Power Rangers is introduced as this. Even after his slide into has-been territory, it was still a very real, very frightening moment when he appeared in the Command Center after capturing Kimberly and forcing the Rangers to pilot his evil zords. His subsequent hand-to-hand fight with Tommy later confirmed his status in this category.
Star Trek: The Original Series: Khan Noonien Singh once ruled a quarter of Earth back in the day. He was even called "The best of Tyrants" in some circles.
An example from Deep Space Nine would be the Founders, a cabal of scientists who use genetically-engineered troops and designer viruses to keep their subjects in line. The Founders, renowned for their xenophobia, were later unmasked as hermits who reside on a featureless, arid border planet. Since the Founders were persecuted throughout history, they made it a rule never to venture from home (unless on a reconnaissance or sabotage mission). When the Klingons managed to locate their planet and destroy it, it turned out that they had vacated without leaving any trace.
His Divine Shadow from Lexx. He ruled over a theocracy of 20,000 worlds with an iron fist for millenia. All for the purpose of using humans to defeat themselves by reducing them to willing slaves and livestock.
The Scrubs episode "My Princess" parodies this, where Dr. Cox tells his 4-year-old son Jack a fairy tale starring his colleagues from Sacred Heart Hospital in the various archetypes. The irritable Dean of Medicine Dr. Kelso becomes the Dark Lord Oslek, an Affably Evil overlord of the land. He has a cowed, hunchbacked assistant (Ted) and punishes all those who enter his forbidden forest.
The Goa'uld of Stargate SG-1 are an entire race of this with an accompanying god complex. However, only the highest ranking ones (the so-called 'System Lords') have enough territory and forces to back the claim up, with the rest of the lesser Goa'uld serving one or another of the System Lords and usually plotting their downfall. They collectively control most of the Milky Way Galaxy at the start of the series, but are deeply fractioned and fighting each other more often than outside threats.
Innumerable examples from Dungeons & Dragons settings and fiction, including the evil gods Takhisis, Bane, and Hextor. Possibly the ultimate example from the RPG is Asmodeus, the King of Nine Hells — the game's equivalent to Satan.
In Forgotten Realms, the god of tyranny Bane is the clearest example, and his church works with mortal overlords here and there, including Manshoon with his Black Network. The conqueror Yamun Khahan, a pastiche of Genghis Khan (not only rumours about him are quoted almost verbatim, but the other names are used as is). But is more of a subversion: a ravenous warlord bent on conquering the known world through endless war, yet turning westward was a change of course forced on him in the Thayvian campaign's dead end, and he was a Benevolent Bossadored by his people (not unlike the real-world Khan).
And then there are the Infernal Exalted, who must play this trope to the fullest, since it's their way of working off Torment. As per usual, this also has a Dark Is Not Evil aspect, as Acts of Villainy aren't actually inherently evil (The one drafted by Kimbery, for example, asks that you give your opponents Cruel Mercy...but doesn't actually have provisions for making it so that living is a Fate Worse than Death).
Commonplace in Warhammer 40,000, with every Chaos Lord, Dark Eldar Archon and Ork warboss, and half or more of the Imperium's governors.
The Fantasy version of Warhammer as well with the Dark Elves, Beastmen, Warriors of Chaos, Vampire Counts, Skaven, Some of the Tomb Kings, Orcs and Goblins. And Ogre kings are not called Tyrants for nothing.
Makuta Teridax in BIONICLE, especially when he takes over the universe.
The main characters in the Overlord series are archetypical Evil Overlords who wields hordes of gremlin-like creatures known as Minions, have mistress(es) and generally look like Tin Tyrants with Glowing Eyes of Doom being the only visible part of the character. The first game lets you decide just how evil the Overlord can be, either a destructive tyrant to a leaderbeloved by the peasants. Although at the end it turns out that you're just a patsy for the real one.
While canonically the Overlord of the first game was apparently a Noble Demon who saved the Elves from extinction and kept Rose as his Mistress, his son in the sequel is much more evil, being either an Ax-Crazy butcher or a Dominator who enslaved entire populaces to his whim. Lord Gromgard of Overlord: Dark Legend is portrayed as more an Anti-Villain who while still an Evil Overlord is a benevolent tyrant better-liked by his subjects more than his Jerkass siblings.
Bowser from the Super Mario Bros. series fits this to a T in almost every game (sometimes even ones where you're just Go Karting with Bowser), from ominous castles/lairs, plans for world/universe domination, and infinite hordes of largely incompetent goons.
Makai Kingdom reveals that Overlords are a dime a dozen in the Nippon Ichi'verse, as anybody with enough mana can rule over their own collection of vassals and worlds.
Laharl, Disgaea's resident Overlord — though the first half or so of the game consists of you making the role legit (he's been asleep for two years thanks to Etna poisoning him). Other overlords in the series include Baal and Priere.
The titular character from the Legacy of Kain series spends a lot of time as this. He does take breaks to save the world, but he actually just wants to keep it alive so he can keep lording over it.
Ultimately averted though, Kain wants to purify the corruption of the world and make it a vampire utopia because vampires came first and the world rightfully belongs to them. (He succeeds in getting it on the right track, but judging by blood omen 2, which results from the paradox he makes, there's a long way to go).
Also, Deathwing. Although he is arguably the (literal) Dragon to N'zoth, we never see N'zoth, therefore, Deathwing. Complete with Spikes of Villainy in human form. He is also Dangerously Genre Savvy. The person prophesied to destroy was the victim of an assassination attempt, and Deathy REFUSED to the point of punishing his idiot minion Archbishop Benedictus into making ABSOLUTELY SURE Thrall was dead before Deathy made any more moves. Benedictus either lied or made a mistake, because Thrall was perfectly healthy and alive. Screw you to Deathwing, maybe?
Azshara to the Naga. Though she is of course more of a Dark Queen than a Dark Lord.
Final Fantasy villains often fall into the Evil Overlord bin: but curiously, very seldom the actual Big Bad.
Gestahl of Final Fantasy VI is an evil overlord, but sadly also The Unfought. Kefka is also an example, and is one of the few that actually is an Evil Overlord at the end of the game when you fight him.
Rufus Shinra and his father in Final Fantasy VII, since the ShinRa company essentially rules the world.
Ultimecia of Final Fantasy VIII rules all in the future. And she is a rare female example.
Exdeath of Final Fantasy V is another good example. He also has the distinction of being the most evil tree to ever appear in any form of media, and certainly the only one who is also the Big Bad.
Quite possibly the best example is the Emperor from Final Fantasy II. He's a major military power throughout most of the game and when he dies, he becomes the freakin' ruler of hell. He also seeks to overthrow Chaos in Dissidia: Final Fantasy. Quite possibly the only thing keeping him from being more popular is Final Fantasy II being the most overlooked game of the series.
In Fire Emblem: The Sacred Stones, Emperor Vigarde suddenly attacks the peaceful allied kingdom of Renais. He does not actually reveal himself to the heroes, only to the player appointing new generals who are just pawns in a greater plan by The Demon King, Lyon, and Riev. In another cliche, he was in fact not the Big Bad or even in control of his actions, since he has been dead for months prior to the game's introduction and was being animated by Lyon's magic.
Nergal in Fire Emblem 7 has this to some extent, but not as much as others like Zephiel and Alvis.
Alvis in Fire Emblem 4 is practically a textbook example, except he actually has some motives.
As is Zephiel in Fire Emblem 6, though he is ultimately not the Big Bad.
King Desmond in Fire Emblem 7 can be seen as a similar way, but he does not actually try to hinder the heroes. He in fact wants his favourite child to be the heir, not Zephiel.
Ashnard in Fire Emblem 9.
Varesh Ossa in Guild Wars: Nightfall is a very good example, although unlike other cliched evil overlords, she is in fact control of her actions and knows fully well what she is doing.
The Valuan Empire in Skies of Arcadia has both the Queen and her general Galcian.
Final Fantasy Adventure/Mystic Quest and its remake Sword of Mana has an overlord as a villain, they even blatantly name him "Dark Lord". He is not actually the Big Bad, to no one's surprise after years of similar storylines.
Grigori Rasputin attempts to become this in Shadow Hearts: Covenant.
Magus the Fiendlord from Chrono Trigger fits this trope rather well: he has an ominous castle, leads an army of fiends and wages war on humanity. However, his motives make him more of an Anti-Hero, who does what he has to do in order to destroy Lavos and find his sister. He can even join the player's party later in the game.
The title character of Holy Invasion of Privacy, Badman! What Did I Do To Deserve This? mixes this trope with the Distressed Dude, being utterly helpless from abduction by heroes without the help of his God (the player character) and the creatures that inhabit his underground lair.
Dracula of Castlevania. Besides the obvious hints, the "Dark Lord" is his official title, and after he's killed off for good in 1999, said title is still up for grabs. Nobody's actually succeeded in taking it proper. Or wanted to, for that matter, in one case - Soma Cruz from Castlevania: Chronicles of Sorrow, being Drac's reincarnation, came close accidentally, and he had to fight to not turn evil. Dmitrii Blinov nearly became the Dark Lord intentionally in Dawn of Sorrow. Nearly.
In Eiyuu X Maou; Villain Protagonist Felser has this ambition, and goes successfully fast-tracking on his way. The closer he gets to Total World Domination, the more it's revealed that his Motive Rants are right, and that the current leaders really do deserve to be overthrown and punished.
Dark Warlord Zanshin from Throne of Darkness. The player's lord becomes one after taking his place.
Mordekaiser in "League of Legends" might qualify. It's unclear whether he really rules over a Dark Kingdom (not much is known about his exact position in the Shadow Isles' hierarchy), but he has the stereotypical looks of a Tin Tyrant.
Dark Wings has Veslin, the mysterious leader of The Empire. Believed to be an evil dragon, but she might be anything, even a whole group of people. All we really know is that there's something powerful and intelligent driving the Veslians.
Stanley the Plaid/Stanley the Tool of Erfworld is described as an Evil Overlord by Parson because of his use of generic evil creatures and because he has united everybody else into an alliance against him. Stanley is highly offended by this, believing himself to be divinely favored. A divine artifact backs him up on this point. Or not, since croakamancer Wanda Firebaugh has one too, and apparently so does Charlie of Charlescomm.
Baron Klaus Wulfenbach of Girl Genius is something of a subversion. For one thing, he doesn't want to be Overlord — he's there mainly to stop less reasonable mad scientists who ran rampant laying waste to everything. For another, he's not actually an evil ruler — the main rules of his empire boil down to 'don't start fights' and 'turn over all Sealed Evil in a Can for proper disposal'. However, he's ruthless in dealing with anyone (or anything) that threatens the stability of his domain, and he's willing to employ at least one homicidal psychopath (Bangladesh DuPree). Although his willingness to use DuPree is entirely based on the fact that she can be relied on to do the least pleasant jobs Klaus requires without hesitation, and keeping her around means that she's one less problem he has to deal with.
It says something about his empire that their motto is "Don't Make Me Come Over There". Part threat, part Badass Boast, if you break his rules, he will come over there, and he will make you regret it.
It also says something that less than three years after he freezes himself and Mechanicsburg in time his rule is viewed almost universally as a lost Golden Age.
Xykon from The Order of the Stick is in many ways a parody of the Evil Overlord stereotype, though he's as genuinely evil as any other. It might be better to say that Xykon started out as a parody Evil Overlord, but it gradually became apparent that goofy as he can be, when you get down to it he's the real deal and every bit as dangerous as you'd expect an Evil Overlord to be.
General Tarquin is one of the Men behind the Dragon to the Empress of Blood. He's found his chances of survival are improved by acting as a mercenary commander for other Evil Overlord wannabes rather than sitting on the throne himself, but he still runs the show along with his Non-Human Sidekick. He's also so Affably Evil that it is approaching Draco in Leather Pants levels of sympathy among a portion of the fandom. Others, it seems, like him less with every strip.
Lord Horribus, at least during the "That Which Redeems" arc. Oddly enough, Horribus is really only second-in-command of the demon armies. The actual Demon King spends the entire Demonic Invasion on the toilet.
A wonderfully Crazy Awesome version is found in the "Holiday Wars" storyline where Bun-bun realises he can become one and Take Over the World by becoming the Anthropomorphic Personification of all the holidays. (Being the embodiment of Halloween gives the right "dark" flavour among what would otherwise mostly be too cheerful portfolios.)
Terra: Northazul Kalar, Sovereign of the Asurian Empire. Leader of a powerful empire with his own personal army in addition to the official one, dressed all in black armor with fur trim, is known to have ordered at least one political purge, et cetera.
In The Gamers Alliance, various evil overlords have appeared in the three ages, for example Arawn Losstarot and Distreyd Thanadar XII.
Baron O'Brien is set up to look like one in Wormtooth Nation, but it's later subverted: he's just trying to hold the dying city together. Not that he's a nice guy, but he's far from evil. This makes since, since he was based on the character of Oberon from A Midsummer Night's Dream.
Xiaolin Showdown has several. First there was Wuya. She was soon followed by Chase Young, Mala Mala Jong, the Sapphire Dragon, Hannibal Roy Bean, Robo-Jack, Panda Bubba, Gigi the killer (French) plant...
Earl of Lemongrab of Adventure Time appears to be a parody of this trope. He's definitely a tyrannical overlord, but he isn't actually evil. Rather, he's really really stupid, mean, and obnoxious. While his intentions are good and he harbors no malice towards anyone, he does succeed in sending everyone in the kingdom to the dungeon for their whole lives. He comes across as a stupid, mildly autistic teenager who was given a position of power that he really should never have had in the first place.
Lord Darkar of Winx Club has a castle, plenty of minions, and is very powerful, though he never controls anything beyond his fortress.
The Ben 10 franchise has good ol' Vilgax, the series' first Big Bad. As the show has more of a Rogues Gallery approach than all evil coming from one guy, he's got plenty of competition:
Milleous, aka "Lord Emperor Milleous, Light of the Incursion Empire, Destroyer of Galaxies, Keeper of the Conquest Ray, all beings tremble-" (that's the farthest anyone's ever gotten when trying to say the title.) At first the Incursions were played for comedy, but have recently come in force to become the series' new Big Bad.
His daughter counts too. Attea is all grown up, Took a Level in Badass, was (provisionally) forgiven for her original betrayal, and is The Heavy. So, we add to the list "General Attea, Princess, Scion and Teen Supreme of the deathless Incursion Empire, Highest Commander of the celebrated Calaveras Legion..." and so on.
Adwaita rules the magical realm of Ledgerdomain with an iron fist. I Know Your True Name is in effect, so the Alpha Rune with the true name of magic itself makes him practically a god. Recurring villainess Charmcaster sought to free her world from him, actually departed on friendly terms with the heroes, and went back. Next time we see Ledgerdomain, it's still under the control of an ironfisted dictator - namely, Charmcaster. The next round with her sees a few thousanda few people die...like the heroes. They get better, as she realizes sacrificing a world to revive her beloved father was going too far, but she was last seen still in complete control over Ledgerdomain.
One of Ben's transformations is this. Turns out any small part of an Ectonurite contains his consciousness - including the Omnitrix sample. Ghostfreak breaks free of the Omnitrix, restores himself, and proves to have been the evil overlord of his own world who sought to be the evil overlord of everything. He even manages to take over Vilgax's homeworld... for one episode, anyway, but damn if that wasn't impressive.
Ghostfreak recently tried teaming up with the former Evil Overlord of his own solar system. However, the vampire-like Lord Transyl was last seen imprisoned floating in space with a nice view of the sun, so it's safe to assume he won't become a regular part of the rogues' gallery.
Statler: You know what I would do if I were an Evil Overlord? Waldorf: Oh? What's that? Statler: Quit. They always try to rule over everything. Would you want to rule this world? Waldorf: Nah. It's more fun to make fun of it! Both: Doh-ho-ho-ho-ho-hoh!