Irenicus from Baldur's Gate 2, it isn't that he revels in being a villain, he simply does not care enough to bother denying the charge.
"No, you'll warrant no villain's exposition from me."
Dorn Il-Khan from EE is another example. He's a mass-murdering Blackguard and openly admits as such. One of his funniest scenes is when he mentions that he and Gromnir came from the same orc tribe, but Gromnir's antics disgusted even Dorn and the orcs so he was thrown out. Dorn even feels the need to point out that even he has standards at all.
All evil party members in the game, to some extent. Thanks to the game's reputation system, they'll start to complain, and eventually may even attack you or quit the party in disgust, if your reputation gets too high (meaning that you're regarded as heroic rather than villainous by NPCs). This includes the characters who ought to be smart enough to recognize the benefits of being a Villain with Good Publicity such as Kagain, a greedy, yet small time-evil dwarf with 15 Intelligence who will complain even when you're well paid for you work.
The Mad Doctor from Epic Mickey. This is especially obvious in the sequel The Power of Two, where he sings a song about this, "The Mad Doctor's Plan", and also title a TV show he created "The Mad Doctor's Wonderful World of Evil".
Dear diary, who's the maddest mad doctor of all ? Wonderfully evil meeeee !
Considering that the carnival of CarnEvil is named, well, CarnEvil, pretty much all of the villains qualify since the game makes absolutely no efforts to hide that fact.
Nemesis from Catacomb Fantasy Trilogy has the goal of destroying all that is good, and his mausoleum contains plaques "dedicated to Nemesis and his great evil." A bit of a Flat Character, maybe.
The non-Naughty Dog installments of the Crash Bandicoot series portray many of its main antagonists as card-carrying villains, especially as the series took a more comedic turn.
Arkham from Devil May Cry is obsessed with evil and spreading it wherever he goes, referring to the term "eeevil" with religious reverence as he carries what must be the Antichrist's Bible for Dummies over his heart. Vergil simply ignores him in these moments.
Most of the evil races in Galactic Civilizations take so much joy in their skull collections. If you're playing an evil race and are on good terms with other evil races, they may occasionally warn you that the good guys want to stop both you and them from torturing people.
Bio-Haz, in the obscure Game Boy RPG Great Greed, is a textbook Evil Overlord trying to conquer Greene Kingdom, and he's generating as much pollution as possible because it makes him and his army stronger. It's not until the end of the game that you learn he has another motive besides his great greed; he wants to save the human world from pollution by using Greene Kingdom as its garbage dump.
In the Human shields trailer for Hatred, the Villain Protagonist refers to himself as a "fearless remorseless genocide machine, cold and deliberate".
ALL of the antagonists in Hero's Realm fit the bill, but special mention goes to Balthalas, who sports a fantastic Evil Laugh to boot.
King Squid from Jables's Adventure outright identifies himself as "the villain" and tells the hero, Jables, that it's too late to stop him from...to be honest, King Squid never really gets to explain what, exactly, his evil scheme is.
Malefor, the Big Bad of The Legend of Spyro trilogy, has absolutely no problems with his title as The Dark Master and, in fact, took the name himself. He's also a third sphere version intending to destroy the world. Unlike most examples of this trope, he's played dead serious and is pure terror.
Ganondorf, called Ganon in his boar-demon form (which is becoming rarer these days, as he ages and gets more of a handle on his temper), is a very lifelike example of this trope. He openly calls himself the Great King of Evil, the Dark Lord, even the Prince of Darkness; he seeks World Domination and has a memorable Evil Laugh; he performs human sacrifices when they get him what he wants (which is pretty rare, but still); he regards civilian populations as an obstacle to be overcome (he left Hyrule a heap of ruins in the first game, conjured up a magical plague in A Link to the Past, killed most of the country in Ocarina of Time...); and he enjoys chaos for its own sake, as well as a means to an end. (This is why Evil Only Has to Win Once is consistently averted in the Legend of Zelda series.) He reflexively conspires against any superiors he may have, doesn't even try to form alliances, and has only once (in The Wind Waker, in his increasingly gloomy middle age) even attempted to talk in terms of right and wrong. But he's brave, intelligent, quick-witted, and strangely charismatic; we've never seen him take hostages or use torture; he doesn't want revenge against those who defy him (indeed, he enjoys a good fight with a brave enemy, and doesn't try very hard to detect or destroy resistance against his rule); he can be kind in small matters, even while being appallingly destructive in the big ones; he doesn't hold grudges against any enemy smaller than the Kingdom of Hyrule as a whole; and his followers are intensely loyal to him. It's not pleasant to be an innocent bystander when someone like this is around, but it's easy to see how he lives with himself; imagine a pirate chief or a mercenary captain, plus enormous magical powers. The Legend of Zelda: The Wind Waker gave him a somewhat sympathetic backstory, but The Legend of Zelda: Ocarina of Time established quite clearly that he likes what he does — far too much to be sympathetic himself.
Demon Lord Ghirahim and his master Demon King Demise in The Legend of Zelda: Skyward Sword don't really have a goal or motivation, other than to be evil. Demise is literally the Devil of the setting, though (and Ganondorf derives much of his power — and his demon-pig alternate form — from Demise's influence); so perhaps they get a pass on this.
House Steiner in the Mechwarrior game franchise: on the couple of occasions you aren't fighting them, they're setting you up for a murderous betrayal. The original BattleTech universe portrays them as more morally ambiguous. It's justified in Mech Commander 2 and MechWarrior 4: Vengeance/Mercenaries, as they are being lead by Katherine Steiner-Davion.
Mega Man Battle Network has Doctor Regal, a representative of moral relativism taken to its extremes, is a very disquieting type 2 Card-Carrying Villain, whose objective is to make everyone as evil as he is, first by gaining control of Duo's asteroid, then by trying to connect all human minds to the Soul Net, and then using Nebula Grey to corrupt it. Unlike most such villains, he is not played for laughs and, in fact, comes out as one of the most threatening and chilling characters in the whole series.
Most of the Path of Dark class promotions in Might and Magic VII have a name that is either more associated with not-quite-a-good-guy than their Light counterpart (Warlock vs Arch Druid, Bounty Hunter vs Ranger Lord, etc) or invoke darkness (Priest of Dark, Black Knight). The Paladin promotion is called Villain, and yes, the guy that promotes you to it uses it himself. In the same game, William Setag is a self-proclaimed Villain. He can train your Crusaders to be Villains, too; it involves helping him kidnap the fairest lady in Erathia, just for the sake of doing it.
The Genma of the Onimusha series revel in being referred to as "evil", most notably in the second game (evident by the final boss being the Golden Evil Statue, and also by the content of some in-game documents).
Team Rocket, introduced in the original Pokémon games. They not only declare how evil they are repeatedly, but generally seem more concerned with making sure that Pokémon are harmed and exploited than actually profiting from their plans.
Also of Pokémon fame, Team Meanies of Pokémon Mystery Dungeon. They aspire for world domination. Their evil schemes include rescuing a little boy so someone else's mother will give them a reward, trying to get a worm to join their team, stealing your mail, and, this being slightly sinister, rousing up the entire town you live next to into hating you and wanting your blood.
Their counterpart in the sequels, Team Skull (Team Poison Rose in the Japanese versions), are the same. Their only motivation is greed and harassing the players' team to make them look bad. Compared to the real Big Bad of the game and his Dragon, they're almost the Team Rocket trio in Pokémon form.
Team Flare from X/Y. According to the first mook you meet, their goal is "to make it so we're the only ones who are happy!". Later in the game, they upgrade it to "alive".
Chairman Drek makes Nefarious look like an amateur. The sheer glee he gets out of performing and boasting about his pointlessly evil acts, such as literally tearing apart, bombing and polluting entire planets (including his own planet) as part of the mother of all money-laundering real estate scams.
Charnel of Sacrifice, occasionally taken to rather humorous levels given he's an evil god of slaughter.
Charnel: He lies! Do not believe anything he says! James: ...What if he tells me you're a villain? Charnel: Don't believe anything else he has to say!
Another bit with him:
Pyro: Why should [the gnomes] suffer for the benefit of savage and brutish beings like the trolls? Stratos: I see only one savage and brutish being here... Charnel: Come, now, we mustn't forget me!
The Sexy Brutale: The games make it clear in the tutorial that the staff are murdering the guests. The staff all wear creepy gas masks and you will regularly hear them insulting their victims or quipping nonchalantly about the murders before or after the fact.
The Sims games let you revel in your evilness with the proper traits.
In The Sims 2, the Fortune aspiration often invites the Lifetime Goal of 'Become a Master Criminal'. In the 'random event cards', one of the two options offers on one involves putting the hero in a death trap while monologuing. note The other being more along the lines of just shooting them.
Generally Dr Ivo 'Eggman' Robotnik believes that his superior intellect means the world would be better off with him as a ruler, but he makes no pretence about being the villain, and seems to openly revel in the fact. Just the same he manages to be a fairly interesting character, largely because of how stubbornly persistent, childish, over the top and ridiculously inventive and resourceful he is.
The Ilwrath of Star Control II go on at length about how evil they are, as a matter of religion. They certainly do enjoy torture, genocide, murder, etc. However, you can induce a Logic Bomb by pointing out that, although they are certainly evil by external measures, by following the tenants and customs of their society, they are, in fact, good. Unfortunately, all this accomplishes is to convince them to try to slaughter you for being an annoying twerp.
Bowser actively prides himself with being seen as EVIL, seeks evil locales for his castles, and enjoys being called "your vileness". Although, over time, he has also begun to pick up Noble Demon traits as well, with the Mario RPG's in particular showing that Bowser is capable of goodness, at least to some degree (although he doesn't like to admit it). Generally, how evil Bowser is depends on his role in the game and whether or not he is the Final Boss; with the main platformer series presenting him as more of an Evil Overlord and spinoffs presenting him in a more sympathetic light.
The Smithy Gang from Super Mario RPG wish to turn the entire Mushroom World into a mechanical wasteland and as Smithy says himself: "Get rid of all wishes and create a world filled with...WEAPONS!!". It's not known if most of the gang actually thinks of themselves as evil however we do get this line from the AxemRangers:
Judging from a certain Scream Fortress 2014 line, Merasmus of Team Fortress 2 seems to revel in being evil.
Merasmus:Most villains don't think they're evil. They think they're heroes. Not me! I'm reclaiming it! Evil wizard! I'm rotten to the bone and I don't care who knows it!
Complicated literal case with Seiga Kaku of Touhou fame. She's a prideful, self-centered, Manipulative Bitch of a "Wicked Hermit" who styles her Spell Cards with names such as "Demonify 'Zouhuo Rumo'" note 走火入魔: A state of frenzy often associated with the mismanagement of the "vital forces" and "Evil Sign 'Yang Xiaogui'" note 養小鬼: A sorcery which enslaves vengeful spirits by using them to reanimate fetus corpses. She has no regard for the course of nature, flipping off both Heaven and Hell with Immortality Immorality and being a necromantic (and possibly necroromantic) Evil Mentor whom's main reason for doing anything can be chalked up to "It Amused Me"... She's also a very friendly and cheerful woman who loves socializing and hanging out with "interesting" people, and aside from the whole desecrating-of-the-dead-in-order-to-raise-them stuff, she never really does anything particularily bad.
WarCraft: Gul'dan (in both of his incarnations - original and the Warlords of Draenor AU version). While Ner'zul had to be deceived into selling his race into serving the Burning Legion, Gul'dan went along with Kil'jaeden's plans willingly. He says several times that he doesn't care what happens to his race, and that he's willing to sell the orcs into demonic servitude solely for the purpose of getting more power for himself. He even proudly calls himself "Darkness Incarnate" several times in the franchise.
The Wolf Among Us has one appear in Episode 3 with Bloody Mary, whose idea of a fun time is living up to her Urban Legend namesake to kill her victims and feed their lungs to the family dog. She re-appears in Episode 5 and talks about how she wishes she'd been around to see people running in terror from the Big Bad Wolf. before he eats her.