An inversion in Adventures of the Galaxy Rangers: crime boss Jackie Subtract has a twin brother, Aiden. Aiden is a harmless inventor with a squeaky-clean criminal record who is mistaken for his brother far too often for his liking.
The Adventures of Puss in Boots features an evil twin of Puss in Boots from The Multiverse, who after discovering the existence of said multiverse seems to be no longer content just being emperor of his own world, but wanting to conquer the entire multiverse as well.
In Aladdin: The Series, Chaos makes an evil twin of Aladdin when he discovers that Fate has destined that Aladdin always wins. To even Chaos' surprise, it came with an evil Genie as well.
An interesting example in one episode of American Dad!. Stan and Francine debate whose methods of child-rearing are better, so Stan puts it to the test: he has the CIA clone Steve and raises that one (whom he dubs "Stevearino") while Francine takes care of the original. As a result of Stan's Spartan methods, Stevearino turns into a brutal psychopath who kills cats for funnote For the record, Francine's babying ends up turning Steve into a fat, lazy slob who takes advantage of her kindness, showing that the two of them have to balance each other out.
Played for Laughs in Arthur episode "Binky Rules". When Binky Rules graffiti is going up around the school Binky gets blamed for it. Buster tries to solve it, and comes up with the theory it is being done by Binky's evil twin who is trying to ruin Binky's life so he can take over.
In the first season finale of The Avengers: Earth's Mightiest Heroes, Captain America gets knocked out, then duplicated, by a Skrull invader. This Skrull eventually breaks up the Avengers, then tries to sway human support for his race re-colonizing the Earth and enslaving them.
Batman: The Brave and the Bold "Deep Cover for Batman" features a version of the alternate-universe evil Batman counterpart Owlman who's appeared elsewhere—he doesn't match any recognized iteration, though; is not Thomas Wayne Jr. or the existentialist type. Brave and the Bold isn't really in Earth-1, so presumably its Mirror World isn't really Earth-3. Also features a good Joker who wears something like the Red Hood costume from one of his back stories and goes by that name. Somewhat cracked, but a good guy. Slight Mid-Atlantic accent.
Albedo in Ben 10: Alien Force and Ben 10: Ultimate Alien is an evil Galvan who created an Omnitrix that worked by copying Ben's, and therefore had the "default setting" of looking like Ben, rather than a Galvan. He was then Mode Locked as a Palette Swap of Ben when the Omnitrices reacted to each other.
In the Bounty Hamster episode "Twin Cheeks", Cassie comes across the roughest, toughest bounty hunter around — her alternative universe self! While certainly meaner, she actually turns out to be not quite as bright, and loses to the Real Cassie in a game of spaceship chicken.
Evil Buzz Lightyear, a Buzz from an alternate reality who's, well, completely evil as opposed to our hero. And, of course, there's a beard...
Zurg also creates a whole team of evil counterparts to the heroes via cloning (and building them a robot counterpart to XR when they insist). Said clones were not aged to adulthood, however. At the end of the episode, in an aversion of Never Recycle Your Schemes, he tried it again, but aged them too long and got evil senior citizens.
One episode had a plot where the series villains got together and made evil clones of the Power Rings. When the powers combined, they created Captain Pollution, an evil twin of Captain Planet who thrived on pollution and was weakened by clean, pure things.
It's shown that Mad Scientist Dr. Blight had a good twin named Bambi who was against her evil schemes.
Gadget's lookalike, Lahwhinie, from the Chip 'n Dale: Rescue Rangers episode "Gadget Goes Hawaiian" is considered by many to be Gadget's evil twin. How or even if the two characters are related is a subject of debate amongst fans of the show.
The episode "Op POOL" features evil twins from a Mirror Universe, including a goateed Numbuh Four and backwards acronyms for the organizations (with the KND becoming the DNK, for Destructively Nefarious Kids).
The Delightful Children from Down the Lane and their Father are evil twins of their counterparts from that universe. It's implied but not confirmed the same applies to the other villains from the mainstream universe.
Lucius and Wayne Cramp, from The Cramp Twins. Though it's more of a good twin, annoying bully and ridiculously filth-loving twin. With purple skin.
In Superman, Superman encounters his "Bizarro" counterpart, a degenerate clone created by Lex Luthor. In another episode, Lois Lane finds herself in an alternate universe where her death resulted in Superman becoming an unhinged tyrant.
Justice League featured another good-guys-turned-bad alternate universe where, after Flash's death, the "Justice Lords" crossed the line by executing Luthor and taking over the world.
Robotic, yes. Twin, yes. Evil? Batman himself wondered at the end of the episode if it had managed to develop a soul, since it was in anguish at the thought that it might've accidentally killed him (the Bat). So evil — not so much, no.
Yeah, for half the episode you feel nothing but sorry for the poor guy, and pissed with Bats and Alfred for being all What Measure Is a Non-Human? on him. Then he gets possessed by the crazy supercomputer that made him (a Big Bad from a previous episode), and has glowy eyes and tries to take over the internet and use it to replace all humans with androids. Then Bats twigs what a nice guy he was before and tries to talk him down while fighting. Thinking he's killed Batman causes Batbot great pain, so in horror he goes and commits suicide by smashing the Batcomputer and preventing it from taking over the internet.
Don't forget Galatea, evil pawn of the Cadmus project. Twin Telepathy between her and Supergirl may have led her to develop a conscience about her actions — enough to hesitate from killing The Question when he challenges her to do so. But by the time of 'Panic in the Sky', she gives only a mocking reference to fighting the Justice League because they're dangerous, and promptly admits she's in the fight to kill Supergirl.
Brainithor created evil Justice Leaguers to battle the real team once. They were based on the Justice Lords. Since there wasn't a Justice Lord Flash (since the Flash's death was the Point of Divergence in that universe), Flash gets a duplicate based on Professor Zoom (heretofore unseen in the DC Animated Universe, so more like a Shout-Out to him.)
Danger Mouse has an evil twin in "The Good, the Bad and the Motionless," or as DM describes him, "two percent of me." He appears at Stonehenge and challenges DM to a fight.
In Darkwing Duck, there's the recurring villain Negaduck (II), his evil Mirror Universe counterpart. (Negaduck (I), DWD's "evil side" who was merged back into him by the end of the episode, is more of an Enemy Without.)
Reportedly, both versions were meant to be explained/retconned to be the same character, though it's hard to imagine how that would have happened.
Interestingly, Darkwing's evil side — Negaduck (II), but also his non-galvanized Enemy Without, who acts almost identically — seems to bring out his good sides in a non-moral sense. The original is so conceited and bumbling he often can't get anything done until he really gets dangerous, but Negaduck is simply constantly angry and doesn't stop to pose or fool around. Because of this, the Evil Twin in this case has more attitude and is much more badass much of the time. Of course, he does have the drawback of being compulsively evil for its own sake and Ax-Crazy.
In a visit to the Negaverse (Negaduck (II)'s place of origin) DW meets the Good Twins of Megavolt, Quackerjack, The Liquidator, and Bushroot, a superhero team identified as the Friendly Four.
And, in the same Negaverse, there are evil versions of Launchpad and Honker; Tank (pretty rotten in reality) is good. Oddly, Gosalyn in the Negaverse isn't evil.
Parodied in the episode "Dollhouse Drama", which is also a parody of the Soap Opera concept in general.
The unaired episode "Dexter's Rude Removal", where Dexter builds a machine to take all of Dee Dee's rude/annoying behavior out of her. It ends up creating "twins" of both Dee Dee and Dexter-not so much evil, more like foul-mouthed jerks.
The cartoon version of Dragon's Lair had a episode called "Mirror Mirror", in which Singe disguises himself as Dirk to trick the village people. The episode ends with two morals. The second one? "Evil dragons should learn how to swim."
Played for Laughs in the episode "Aged Heat" of Duck Man, after his family mocks his detective skills, Duckman is convinced that his comatose mother-in-law was replaced by an impostor. It turns out that he's absolutely right. The impostor is Agnes Delrooney, a known criminal and exact look-alike who escaped from prison.
Played for Laughs in the DuckTales (2017) reboot: when asked which of the Duck brothers is the "evil triplet," Huey and Dewey immediately point to Louie... who shrugs and accepts it. It should be noted that he does seem to be the most amoral of the triplets, being materialistic, selfish, sarcastic, and perfectly willing to lie to others. He's still a good guy, though. In Season 2 he actively claims this status when trying to get Goldie O'Gilt to teach him her con artist ways, but she is unimpressed.
Goldie: Better luck next time, rookie. Louie: Rookie?! I'll have you know I am the evil triplet, okay?! Goldie: Sure, you're the scariest bunny in the pet shop.
Played straight by the titular character's evil twin, Evil Jim. His debut episode both lampshaded this trope's appearance on superhero shows in general ("Superheroes and evil twins are like peanut butter and...evilpeanut butter!") and mocked the 'your opposite in every way' aspect.
Jim: If I hate losing, then you must love it! So why not give up now?
Evil Jim: Oh, don't be so literal-minded.
Comically subverted and inverted in one episode, where Evil Jim gets tired of being the only Evil Twin in the universe and uses a Negative Synthesizer to create evil versions of Earthworm Jim's sidekicks, who are polar opposites — the evil version of Peter the Puppy turns into a polite, friendly version of Monster Dog, and the evil version of Princess Whats-Her-Name is lazy and unwilling to fight, contrasting the warrior princess original. However, halfway through the episode the Synthesizer accidentally creates good twins of all of the series' recurring villains, including this most humourous exchange:
Good The Cat: I am Good the Cat. Would you be my friend?
Evil The Cat: I think not. Instead, I will destroy you with an acid furball.
Good The Cat: Then I will neutralize it with an antacid furball.
Evil The Cat: Curses!
Good The Cat: Kisses!
In the same episode, the original Jim manages to snatch the Negative Synthesizer and invert the trope via shooting Evil Jim with it several times, creating an army of good Jim clones.
The Anti-Fairies. There's one of them for every Fairy.
The Crimson Chin's (voiced by Jay Leno) evil Mirror Universe twin Nega Chin (also voiced by Jay Leno), who appeared in the episodes "Mighty Mom and Dyno Dad Meet the Crimson Chin" and "The Big Superhero Wish". In the former he brought all his villain pals out of the comic, at the end he gets defeated by several versions of the Chin (all voiced by Jay Leno).
Lois confronts two Peters on a rooftop. They both make claims to be the genuine article, and she finally shoots one. As she hugs the injury-free Peter his face pops off to reveal robotic insides. She asks "What was that?" to which he quickly replies "Nothing", and the scene cuts away.
Tom Tucker, the news anchor, tried (rather unconvincingly) to invoke this when he was caught with a prostitute.
Stewie creates an evil clone of himself accidentally. No goatee, but a clothing-color inversion.
In "Meg Stinks", Peter gets his hand cut off while driving, but announces that he can regenerate, and grows it back. Cut to the hand regenerating a copy of Peter (with color-inverted clothes), who immediately declares, "My name is Retep, and I am evil!"
In the Foster's Home for Imaginary Friends episode "Squeeze the Day", Bloo fools around with an eyebrow pencil, first drawing Big Ol' Eyebrows and a moustache on his face and pretending to be "Pierre ze Schwan", then adding an evil goatee and pretending to be "Pierre's evil brother". Then he drew an ear on the side of his head and claimed he was "Pierre's third cousin." Things got weird when he put on lipstick and said he was "Pierre's girlfriend" and started kissing the mirror until Mac shows up and things get awkward.
Freakazoid!: Gutierrez makes an evil clone of Freakazoid, which he then sends out to create havoc and commit crimes. He's quickly found out when he refuses to attend a Yakov Smirnoff film festival with Sgt. Cosgrove.
Averted in Frisky Dingo. When the Xtacles find Xander Crews' mentally retarded twin brother and cure his condition with "brain chemical", he quickly becomes evil and swears revenge on Xander Crews until he is promptly shot in the head by one of the Xtacles. The Xtacle then explains that the entire "evil twin" thing made the plot far too complicated for its own good and the rest of the Xtacles agree.
It did a subversion of this trope, where it turned out Bender, as opposed to his "twin" Flexo (another robot of the same model, except with a goatee), had stolen a beauty pageant crown and was ultimately the "evil" one. However, Flexo ended up taking the blame for everything.
Fry: You mean Bender's the evil Bender? I am shocked! Shocked! Well, not that shocked...
In "The Farnsworth Parabox," Professor Farnsworth creates a box containing a whole other universe, which is identical, except for everyone's color schemes and the outcomes of coin tosses. When the group from Universe A (ours) enter Universe 1 (theirs), each is convinced the other is their evil twins. Bender laments that he tries his hardest, and therefore it hurts that there's a Bender more evil than he.
Futurama's spoof soap opera "All My Circuits" also lampshades this with dialogue about the main hero Calculon's 4th evil identical septuplet.
One episode of Garfield and Friends, entitled "Binky Goes Bad", featured Stinky Davis disguising himself as Binky the Clown, after which he starts a crime wave for which the real Binky is falsely accused and is almost imprisoned until Garfield steps in to prove his innocence.
Lampshaded by Garfield when he reads up on Davis disguising himself and exclaims, "Oh, no! It's an evil twin story! It's come to that!"
In Gargoyles, Xanatos had Goliath cloned as one of his attempts to get his very own gargoyle underling. The clone proved to be one of the most evil villains on the show, and it's telling that the normally unflappable Xanatos was visibly bothered by what a cunning and amoral Goliath was capable of(with Owen ominously concluding that he surpassed even Xanatos' genius), and it put him off the "personal gargoyle" idea for good. The clone was unoriginally named "Thailog"; when asked why they didn't name him "Htailog" the writers joked that Keith David (voice actor for both) was a scary guy, and they didn't want to see his reaction at having to pronounce it.
Notably, the show averted the common "Evil Twin switches for Good Twin" trope; due to a flaw in the accelerated aging process, Thailog's pigmentation is different enough from Goliath's that the two couldn't be mistaken for each other except in very poor lighting.
Gravity Falls has a Show Within a Show called Duck-tective, where the eponymous duck is revealed to have an evil twin brother who shot him in the season finale. This is a parody of the Gravity Falls second season mid-season twist revealing that the main protagonist's great-uncle has a twin, albeit not an evil one. Bonus points for the fact that the twin also shot one of the main protagonists in the finale, although it was with a memory gun.
In one episode of The Grim Adventures of Billy & Mandy, Grim takes Billy and Mandy into a shadow world where their shadows manifests as their opposites. Mandy meets her good double, while Billy meets his stupid double. And no, that's not a typo. The stupid Billy spends much of the episode barking like a sea lion.
In the Gummi Bears turns out that Duke Igthron actually has the opposite: a Good Twin, his twin brother Sir Victor, almost identical except for the fact that Igthorn is dark-haired and has a beard. This comes in handy in one episode when Igthron impersonates his brother, who is an admired hero among the townsfolk and one of the most trusted men of King Gregor.
Skeletor uses a magic mirror to create an evil twin of one of He-Man's allies. When the ally tricks Skeletor into allowing a good duplicate into existence, it leads to He-Man asking both Skeletors to claim to be his friend. The original Skeletor is too evil to comply.
In another episode, Skeletor creates a He-Man impostor named Fakor after temporarily gaining greater magical power. The impostor is last seen plummeting into the abyss surrounding Castle Greyskull after a battle with the real He-Man; Skeletor implies that he intends to recover Fakor somehow, but he isn't seen again.
An episode of Johnny Test has Susan and Mary sucking out the negative part of Johnny's psyche; then, during a power outage, the beaker containing it falls and turns into an evil Johnny, while the original Johnny slowly degrades into a Nice Guy.
Not a real 'evil twin' per se, but Owlman, in Justice League: Crisis on Two Earths, is exactly like Batman, except a sociopath. To be honest, most of the JLA counterparts are like that, but especially Owlman.
Batman: [to Owlman] There is a difference between you and me. We both looked into the abyss, but when it looked back at us, you blinked.
Subverted in the episode "The Ron Factor". The leader of the Global Justice Network, Doctor Director, is shown to have an evil twin named Gemini. He's her evil fraternal twin, of opposite gender and vastly different appearance, but with an almost identical eyepatch. This is based on Marvel's Nick Fury and his evil twin Scorpio, by the way.
When Private Dobbs, with whom Dr. Drakken swapped bodies to gain access to a weapon, contacts Kim Possible for help and explains that he isn't Drakken, Ron accuses him of being Drakken's evil twin. Kim replies that Drakken is the evil twin.
The short lifespan of Megas XLR still had enough time to introduce Coop to an evil Alternate Universe version of himself and one of Kiva, in the two-parter "Rearview Mirror, Mirror". The weird thing is that Evil Coop was supposed to be competent (as opposed to good Coop's idiocy) but for no reason decided to trade Megas in for a "better" bot (guess he forgot that Megas can shoot FREAKING BLACK HOLES OUT OF ITS CHEST).
Rikochet from ¡Mucha Lucha! had his leprechaun-esque evil twin, Rick O'Shay. The fact that the two names are homophonous leads to a Who's on First? situation when Rikochet tries to deny the crimes that he's being framed for.
A Potsworth & Company episode featured the Night Mirror, that creates evil twins of good people who look at it. When the ones who look at it are evil, they're the evil twins to their good duplicates. The duplicates (be they good or evil) disappear when they look at the mirror.
More accurately, later on in the comics (from a planned episode which was supposed to be computer animated, but cancelled due to budget concerns) come the Powerpunk Girls, natives of a Mirror Universe. (Mojo Jojo is a good guy in their reality.)
The Punky Brewster episode "Double Your Punky" has a twin of her but she's more mean-spirited than evil. It was created by Glomer from a photograph of Punky in not one of her better dispositions.
Played with in ReBoot. While the "second Bob" is truly evil (he's really Megabyte in disguise), he acts like a good character and even convinces a few people that the first Bob is fake. He even convinced the real Bob that he was a fake. Like the Gargoyles example earlier, this show averted the "switching good twin with bad twin" bit, since "second Bob"'s only claim to being real was that he looked normal while "first Bob" was Web degraded.
The Ghostbusters had to fight ghostly evil twins, the result of their uniforms (contaminated from the battle with Gozer) coming to life.
In a later episode, they face the People-Busters, ghostly versions of themselves from an alternate universe. The "Evil" aspect is open to discussion, however.
Slimer has his own Evil Twin (identical except for a darker green tone) in one episode, escaped from the Netherworld.
On The Ren & Stimpy Show, Stimpy makes a formula which splits people into good and evil versions of themselves. Or in Ren's case, Indifferent Ren and Evil Ren. And his evil half takes more of the formula to become Evil Ren and Hideously Evil Ren (not that Indifferent Ren cares).
One episode ("Alter Ego") during the Sabrina the Teenage Witch segment of the late 1970's era Filmation cartoon The New Archie and Sabrina Hour featured the wickedly mischievous Damina, a raven-haired Sabrina lookalike with a shrill, grating voice. Though Hilda referred to Damina as "Sabrina's magic mirror image" and Zelda implied that Damina was Sabrina's alter ego, the girls addressed each other as "Cousin." They are also a literal example of the Red Oni, Blue Oni trope: rowdy and rambunctious Damina wore red, and the demure and proper Sabrina wore blue.
One of The Scooby-Doo ShowHalloween Episodes, "To Switch a Witch", featured Arlene Wilcox, whose evil twin tried to take advantage of their resemblance to have her executed as a witch. It'd have worked if not for You Meddling Kids.
Played with in Sealab 2021, where a pair of characters gets displaced in time, and Captain Murphy is convinced they are doppelgangers.
Captain Murphy: Tell it to Queen Doppelpopoulis!
Played straight with Bizarro Sealab, who fortunately were even more incompetent than normal Sealab.
On Shelldon, Sheriff is a starfish and when he was split in half, one half was cared for by his friends and remained him, while the other was lost and ended up becoming a jewel thief named Spiky Riptide.
In the first segment of "Treehouse of Horror VII", Bart and Lisa discover an evil twin of Bart, named Hugo, living in the attic and obsessed with "reuniting". Their parents and Dr. Hibbert admit that the boys were born conjoined, but were separated at birth and Hugo was locked away after they realized he was evil. However, it's subverted when Hibbert looks at their scars and realizes that Bart is, and always has been, the evil one ("Oh, don't look so shocked"). The segment ends with their situation reversed, Hugo being accepted into the family while Bart is locked in the attic and fed nothing but fish heads.
Mr. Burns also fits the trope, even if the only thing known about his twin (who never appeared in the series) is that he/she died from being shot. It's heavily implied Burns was behind his twin's death (and the deaths of all their other siblings) to inherit his parents' whole fortune as he told the tales of their demises to Bart Simpson, who was masquerading as Simon Woosterfield as part of a Prince and Pauper plot.
Skylanders Academy has Strykore, a Canon Foreigner, who is the twin brother to Master Eon. He didn't start out as evil, though. He was orginally on the side of good alongside his brother and their friend Kaossandra. But Strykore grew more and more greedy for power, which led to him getting his hands on illegal spell books and being corrupted by their darkness. At the end of The Great War he initiated, Kaossandra sealed him away in the endless void, forcing her to give in to her evil side to keep Strykore locked up. Because of this, Strykore doesn't get properly established until the end of season 2, where he is released from his prison by Kaos.
An episode of Sofia the First has Sofia creating a clone of herself in a pink dress to play with a visitor while she goes to a hootenanny, but the clone turns out to be this. Clover finds out that Sofia did something wrong when he takes a bite out of an apple she cloned and finds that it's rotten.
This was effectively parodied in the South Park episode "Spookyfish", in which Cartman's Evil Twin was soft spoken, considerate, and generous, so Stan and Kyle try to send the "real" Cartman back to the Alternate Universe instead.
In the cartoon version of Space Ace, besides Hexter in the games, Dexter has a second evil clone named Baby Face Nerks, who looks like Dexter, but does not energize, and also wears a cowboy hat and wears a bandana around his neck. He appears in "Wanter Dexter!".
The original Space Ghost series had a straight example of this, with the evil "Space Spectre" crossing over for one episode from a parallel universe. No evil twins of Space Ghost's friends, however, since Space Spectre works alone, a fact pointed out by Space Ghost as the reason he was able to defeat Spectre.
The Space Ghost Coast to Coast episode "Switcheroo" (the one in season 3, not 4) introduces Space Ghost's Evil Twin brother Chad... who, of course, has a goatee.
Stunt Dawgs villain Richard P. Fungus and his insane twin brother R. Peter Fungus.
Teenage Mutant Ninja Turtles (1987): The episode "Donatello's Duplicate" has Donatello make a duplicate of himself to help with his lab work so he can have some more time to relax. Unfortunately for him, the twin is an egotistical Jerkass, who eventually sides with a gangster who wants to rule the city, so the twin builds a second duplicator to create copies of rats to swarm the city. The Turtles eventually confront the evil Donatello during the climax; he then uses the duplicator on the rest of the team to make evil duplicates of them as well.
In Teen Titans, during "The End" Trigon creates evil duplicates of Beast Boy, Cyborg, and Starfire. A battle ensues.
The Tick has Mucus Tick, an evil clone created by inter-dimensional horror Thrakkazog from a tissue, or rather Kleenex, sample taken from The Tick when he had a cold. Mucus Tick was, appropriately, green and amorphous. The sample was taken from a clone of Arthur, which among its most telling features is that it could only say, "I Arthur." The Tick considered that a rather compelling argument when it came time to determine which one was real.
Furthermore, Arthur seems to have an entire race of evil clones in an alien species called the Hey that coincidentally dresses exactly like him, has a language consisting entirely of the word "Hey," and literally worship nothing to the point of wanting to destroy everything.
Hey propaganda is patently hilarious to hear, because to the human ear it sounds less like inspiring prose and more like jaded, cynical hogwash. "Nothing is worth living for. Nothing is worth fighting for. Nothing is beautiful." You get the idea.
Arguably, Tick also has "Barry Tick," who is similar only in theme and they wind up fighting each other over who gets to use their name.
Total Drama: Amy is this to a literal sense to Sammy. She makes absolutely no effort to hide her borderline psychopathic tendencies (she attempts fratricide in the very first episode of Pahkithew Island) and she looks almost completely identical to Sammy save for a black mole under her right eye. Her official title is literally "The Evil Cheerleader Twin". And yet, she's apparently everyone's favorite.
Transformers: Armada had a black version of Optimus Prime appear when they briefly jumped dimensions for... some reason. Actually it was Sideways, but still an evil twin.
In a number of canons, "Scourge" and "Nemesis Prime" are an evil, black repaint of Optimus Prime.
A Botcon Transformers: Animated comic features the Stunticons, destructive Decepticon clones from miscellaneous Autobots (and Lockdown, who's already pretty slaggin' evil.) Toxitron, the one based on Optimus, is a pastiche of Bizarro.
In The Venture Bros., Dr. Venture himself can be considered the evil twin to his brother Jonas Jr., whom he consumed in the womb. While Jonas Jr. is meant to be the true heir to Jonas Sr. and is the superior scientist, Rusty is a failed scientist who has shown himself to be amoral, having created a Joy Can out of an orphan's heart and a Frankenstein's Monster out of a Punch-Clock Villain that his bodyguard killed as well as being generally a horrid father who seems to show mostly disdain for his own sons (though this might be related to the fact that they are shown to be Too Dumb to Live at times).
He even tries and fails to kill a successful, non bald doppelganger of himself from an alternate reality.
Though it does seem to rattle Dr. Venture when Henry Killinger (and his magic murder bag) assumes he'd make a good supervillain/arch-nemesis for his brother. He turns it down when he realizes it, despite that his compound is so much more efficient that way.
One interpretation is Killinger did this on purpose to give Rusty a "Heel Realization" and start him on the path to becoming a better person. Killinger states that his purpose is to enable clients "own best self". Killinger wants to help Rusty become the hero he was destined to be.
The titular character in Widget the World Watcher had an evil twin from another dimension, Ratchet the World Trasher.
Wishfart parodies this in a manner similar to the Futurama example above. When a wishing accident causes Alternate Universe versions of Dez, Puffin, and Akiko to enter their universe, Dez and his friends initially assume them to be their evil twins. However, Alternate!Puffin points out that it's pretty evil of them to make such a nasty assumption so quickly.
Dez: You're right. I’d say we look just as evil, if not more evil, than these evil doppelgangers.
Not actually evil, per se, but Will and Yan Lin gain twins thanks to Nerissa during the second season of W.I.T.C.H.. Will's fights back when she realizes that the real Will is trying to reabsorb her (due to the fact that she's a projection from the Heart of Candracar given sentience), but ends up Taking the Bullet when Nerissa attacks, willingly allowing Will to reabsorb her. Yan Lin's twin goes rogue when Nerissa threatens to take away her sentience if the twin doesn't join her. Unlike Will's twin, Yan Lin's lives on, and the real Yan Lin passes off her duplicate as her never-before-seen twin sister.
Ranger Smith of Yogi Bear fame had an evil twin known as Slippery Smith. Being a fugitive for unspecified crimes (probably mostly theft) was bad enough, but forcibly swapping clothes with his brother and throwing him out to the cops was a Moral Event Horizon. Thankfully (if unsurprisingly), Slippery Smith did not appear in more than one episode.
