Ask That Guy openly admits that whenever he starts showing a conscience or a human side, he makes sure to crush it as soon as possible.
To a lesser extent, The Nostalgia Chick is fully and proudly aware that she's an evil little bitch.
Bennett the Sage outdoes all of them, though—he's traumatized Ask That Guy mentally and physically, and Insano has been shown to have soft spots. Hell, Sage has even claimed to be Satan on multiple occasions (though whether he actually is or not depends on what video you're watching.)
Dr. Horrible's Sing-Along Blog has the Evil League of Evil, an elite organization of Card Carrying Villains (led by Bad Horse, the Thoroughbred of Sin). The Doc himself (who claims to have a Ph.D. in Horribleness) is a Noble Demon who aspires to be a member and says he will show his love interest that he's a true villain. Act I features him practicing his Evil Laugh and discussing his application to ELE; in Act III, he's perfected the laugh and indulges in some hamtastic Evil Gloating.
Their henchmen have a guild/union, so there might be literal cards being carried around.
Vegeta: That's it, everyone dies! Say goodbye to your planet, Kakarot! Goku: That's not very nice. Vegeta: OF COURSE NOT, I'M F**KING EVIL!
Later as he's mortally wounded by Frieza, Vegeta pleads with Goku to avenge him and the Sayian race, telling him about having lived under Frieza's tyrannical rule for most of his life. Goku asks him that if all this wouldn't have happened to him, he wouldn't be evil, and Vegeta replies: "Oh, no! I'd definitely still be evil! If the situation were reversed, this conversation would never have happened. You'd be dead, and I'd be laughing."
Even death doesn't change Freeza's mind; in the first episode of HFIL, he outright tells Cell that he'd rather die a million more times than pretend to be anything other than "a child-killing, people-enslaving galactic tyrant".
The Evil Gamer, evil twin brother of The Irate Gamer, he constantly uses the word "evil", lives in the "Castle Of Evil", and wanted to do an "evil Aflac Duck" for the Aflac audition sketch.
Vendetta. In the web cartoon, Vendetta's main reason to destroy Charlotte seems to be because she thinks Vendetta and the fiends are nice and her friends, although in the TV series, this boils down to "Charlotte is annoying". Same with Mrs. Minty, who is unaware(?) of Vendetta's evilness and treats her like another misbehaving student, which doesn't end well.
Mr. 'Freaking Stinking Cheating' Doom of the Mario Party TV group doesn't particularly mind being seen as the token evil teammate, and uses this as an excuse whenever the others get salty.
Ganondorf, from the Machinima series Melee's End, seems to only act as an antagonist because he was designed as a bad guy.
In Nocte Yin, about a third of the population has Villain in the job description and most of them fall under this category.
The Red Panda Adventures villain the Mad Monkey initially launches a crime spree on Toronto because he thinks the Red Panda's heroism is some kind of scam or con he can get in on by playing the role of nemesis. Once he realizes that this isn't the case, and that the Red Panda is good for the sake of being good, he decides that means he can be evil for the sake of being evil.
SCP-353 of the SCP Foundation is a Plague Master who refers to herself only as "Vector", gathers new types of infectious agents "because I can", and is considered by the staff to have "X-men villain fantasies".
In The Thrilling Adventure Hour episode "Book, Line, and Sinker", Captain Laserbeam foe the Diebrarian concocts a plan to buy remaindered books and force them on schools so that children will have more books than they'll ever need. He thinks it's a brilliant diabolical plan. His henchman Papercut and Captain Laserbeam recognize both that what he's doing is actually beneficial, and that he will stop if he realizes this. Captain Laserbeam throws his fight and even stops Phillip Fathom the Deep Sea Detective from intervening so the Diebrarian can escape and continue his "evil."
In Unforgotten Realms, the Evil Overlord Timmy the Evil spends his evil time discussing his evil plans for the destruction of the not-so-evil heroes with the evil Professor Walrus. All of his evil plans so far include using evil crystals with a variety of evil powers. Evil.
Bakura: Why do we even need the card game at all? Why can't we just push him off the boat?
Marik: No! The card game is essential to the plot! The EVIL plot!
Heavily satired in Kakos Industries as it finds Evil to not just be something business worthy, but capable of being measured, contained and recorderd all for the sake of enhancing it's capabilities to its fullest potential. In fact, not taking immense pride in one's Evil is nothing short of a crime in their society.
Vader himself is no slouch in the card-carrying villainy department. As he puts it, "Everything [Hitler] did, [he's] the motherfucker who invented it."
Thomas Edison proudly states that he screwed Tesla over and electrocutes a puppy just to be evil.
Josef Stalin is completely unfazed by Rasputin calling him "evil" and a "messed-up motherfucker bent in the mind", but is offended when Rasputin implies that he loves his wife.
Blackbeard: Beef with me? Please! I'm the high seas Caesar. This cold heart is many degrees beneath the deep freezer!
Jack the Ripper describes himself as "a human trigger warning" and boasts of having committed crimes so gory even Hannibal Lecter would find them sick and appalling.
Walt Disney brags about overworking his artists and running sweatshops.
Ivan the Terrible accepts and embraces his epithet after killing Alexander the Great.
Cao Cao completely admits he is the villain in Farce of the Three Kingdoms. He doesn't have any choice, since it's Word of God. Doesn't mean he's exactly happy about it.
In this YTP video Dennis Prager is made to look this way. In his pro-communist speech Prager demands that the people acknowledge the evils he committed in his youth and calls for genocide of every group he doesn't like, before signing himself off as "the greatest mass-murderer of them all".
Dennis Prager So please, say the N-word. And please say we love Mao Zedong. And murder all white males. If you don't, your misanthropic not to mention mean spirited! I am the greatest mass murderer of them all, Dennis Prager.
In this similar video, he says "for the students and faculty of our school I am pure evil, and honored to be so!". He teaches his students to be open "Comunazis", advocates for the deaths of more people, and admits to setting your mom's house on fire.
And this one where he says he likes to kill people for fun.
"It Just Works" by The Chalkeaters, a Take That! against Bethesda's performance at E3 2019, depicts Todd Howard as a swanky con mangleefully singing about how he can basically make the same game over and over again, doing little to improve them or fix any coding problems, and overcharging for everything. But because he makes empty promises and puts on stunning shows, people will still buy them because "it just works!" Even after a chorus of Bethesda fans sing about how they don't want the same tricks all the time and they're sick of it, he doesn't listen and just goes back to singing about his strategy just works.
The Last Podcast on the Left: In the "Norwegian Black Metal" episodes, this is the impression the hosts are left with regarding the leading figures of the genre. A bunch of musicians who proclaimed themselves to be True Evil and, over time, "yes anded" themselves into bigger and badder brags until multiple arsons and actual deaths occurred.
The Magnus Archives has this as a trait for a fair number of Avatars of the Powers, but Nikola Orsinov is just so... upfront about it.
Jon: You, um... you killed Gregor Orsinov?
Nikola, in a very singsong voice: Yep! He got really boring, and I'm a monster! I mean, what did you want me to do? Not pull him apart? ... I did use all the bits!
Truly villainous characters in Njal Gets Burned, such as Hallgerd, Thjostolf, and Mord, are usually rather self-aware. Earl Hakon the Bad takes it a step further, embracing his nickname.
SMPEarth: Technoblade qualifies with this monologue.
Techno: When have I ever branded myself as a nice guy? I am the Blood God. I take no prisoners. I am the cyberbully. I just got off from stealing presents from orphans on Hypixel... I have NEVER been a nice guy.