Shadow Archetype has to do with two elements of writing; characters and settings. In this part of the wiki we're talking about character archetypes. For the settings viewpoint, see Shadowland.
Character-wise, it's the part of the personality that embodies everything a character, called the 'Self', doesn't like about themselves, the things they deny and project on to others. To show these things to the audience we need an embodiment of some sort. Around here, we call some of those embodiments things like:
In Cowboy Bebop, it's heavily implied that Vicious is what Spike would've turned into without Julia's influence (and vice-versa).
Revolutionary Girl Utena being a complex psychological piece has plenty of examples, namely: Utena/Mikage (the name is a clue); Nanami/Utena; Akio/Dios; Akio/Utena; Anthy/Nanami. Also, the elevator in the Black Rose arc is all about getting in touch with one's shadow. All the Black Rose duelists become Black Rose duelists by entering the elevator and confessing something, usually that they secretly hate some other character.
Paranoia Agent is ultimately about what happens when someone's Shadow Archetype gets out and starts breaking everyone else's shadows free.
Vash's brother Knives, instead of having an extreme aversion to killing, sees humans as pathetic and inferior, and has no compunction about killing them for any or no reason. Knives has serious self-control issues which occasionally cause him difficulties and turn out to have shortened his lifespan, while Vash being The Fettered is... ubiquitous. His twin isn't just everything-bad-that-he-isn't, he's everything Vash refuses to be. Even more in the manga, where Vash almost flipped out the same time Knives did, and had a suicide attempt and accidentally almost killed Rem, which was met with maniacal laughter, and then he pulled himself together and chose to not give up on people.
Wolfwood is Vash's foil, though Vash may be viewed as the idealism-shadow of either Knives or Wolfwood, who wear Jade-Colored Glasses.
Gendou gives a good idea of how disillusioned, cynical and bitter Shinji could grow up to become. It's even Lampshaded in the Angelic Days manga, which shows Gendou as a Troubled, but Cute (in Yui's eyes!) "nobody loves me so I hate everybody!" teen.
The actual shadow archetype from Jungian psychology shows up, as a shadowy Shinji on a train that reveals truths Shinji doesn't want to face. However, since Shinji frequently suffers from negative opinions of himself he rather likes his shadow and feels it to be much better than he is. This projection of positive value judgements makes his shadow contrast with the typical 'dark' and 'evil' depiction of this archetype.
Among the many interpretations of Fuuma's strange anti-Christ character in X1999 is that he is a Shadow Archetype born out of the dark side of Kamui's nature. In the TV series this character claims to be Kamui's "Gemini" and its implied that if Kamui had been consumed by his own rage and grief, this character would have instead become a Messianic Archetype in Kamui's stead.
The incredibly freaky first appearance of dark Sonic in the Sonic X, in response to the sight of his friends being injured and imprisoned (and exposure to the negative energy of Fake Chaos Emeralds, see: Green Rocks) Dark Sonic emerges from the normally far-calmer (by comparison, anyway) Sonic and proceeds to beat the living begeezus out of a couple of Metarex testing robots. Ironically enough, he was snapped out of it by Eggman.
In Aquarian Age: Sign for Evolution the character Yoriko has two distinct personalities for two of the five different factions in the show, Aryashiki (the side she grew up believing she had to take command of) and Darklore. It turns out that her Darklore persona (which has been causing havoc for most of the series) was as much a part of her as her Aryashiki one and it just took a while for her to realize. She embraces her other half and takes her back.
Yoriko: I kept thinking... I'm not doing those awful things to Kyouta. It's not me. But it was.
It was a little scary there for a while. But it's going to be okay now.
Valvrave the Liberator: Haruto and L-Elf. Haruto winds up as the titular mecha's pilot for brash, emotionally driven, but overall selfless reasons. L-Elf does everything he does for a cold, carefully calculated purpose, and that included attempting to steal the Valvrave—which he would have succeeded at if not for being unaware of the changes it puts its pilot through. Haruto is rather emotional and kind, thinks with his heart, and generally only takes the short-term into account with his actions. L-Elf plans out his strategies literal years in advance and his only moral code can be summed up as successfully bring revolution to my country, nothing else matters. Whereas Haruto is an super-powered being due to his status as a Valvrave pilot, L-Elf is technically a normal human being, but is still widely known as the One-Man Army. Haruto attended a normal high school until the war between their countries, and L-Elf graduated from an elite military academy meant to train Child Soldiers. Yet, amidst all of this, L-Elf is completely hellbent on forcing Haruto to join him in his efforts as Haruto can potentially help L-Elf achieve his revolution as much as five years earlier than he'd originally predicted.
In Pokémon Special, Lance is this to Yellow. Both were born in Viridian Forest, and both have the power to heal pokemon and listen to their thoughts. While Yellow is a pacifistic Friend to All Living Things who just wants everyone to live in peace as a result of this, Lance is a brutal Well-Intentioned Extremist who plans to wipe out all of humanity because he believes Pokémon and humanity to be completely incompatible with each other. (And when they clash? Good. Lord.)
Certain amoral alchemists are fond of telling Edward Elric that he's just like them for trying to bring his dead mother back to life, something he really doesn't want to hear but sometimes acknowledges is true. Arguably, Izumi reacts with anger when she finds out because Ed represents her own guilt at her own attempts to bring her child back to life.
The creepy creature that sits outside the Portal of Truth and selectively reveals ugly truths is a proper, Jungian shadow archetype, and tells Ed "I am also you." Interestingly, he's visually inverted, so he's bright light and not the traditional shadow.
Hohenheim and Father, the Big Good and Big Bad respectively, down to their identical appearances.
Greed may eventually pull his Heel-Face Turn act, but he is this to Ling as well. Both expressed interest in Alphonse's nature as a disembodied soul attached to armor, both are power-craving individuals inclined to do anything to get what they want, and both have a strong unwillingness to lose anything of value to them, which extends to their comrades. Ling however is good-natured and has an openly declared willingness to serve his people, compared to his jerkass Homunculus counterpart who tries to center absolutely everything around himself. Their similarities foreshadow Ling merging with Greed.
Most of the homunculi fit the bill for someone or another: Pride for Edward, Envy for Mustang, Sloth for the Armstrongs, Wrath for Scar, and, as has already been covered, Greed for Ling. Interestingly, Pride is the only one who isn't killed by the hero.
In the 2003 anime version, Wrath is a shadow archetype to Envy. They're both Artificial Humans of Ambiguous Gender, with the same bad taste in fashion, vindictive streak (watch Wrath kill Lust and tell me there's no sadism there), impulsive tendencies (although Envy's are slightly more controlled due to his greater experience), abandonment issues and fondness of displaying a Slasher Smile in combat. The difference is that Wrath has people who genuinely care about him, and is eventually able to lose that anger and pull a Heel-Face Turn, whereas Envy, after 400 years of nurturing his spite, has nothing but deep-seated rage left to him; all that remains is psychosis and self-loathing.
In Haruhi Suzumiya, the title character and Kyon are shadows of each other - Haruhi is the Daydream Believer that Kyon keeps locked away in his mind, and Kyon is the rational aspect of Haruhi that she tries to ignore.
Kenichi and Kanō in Kenichi: The Mightiest Disciple. Kenichi embodies the light aspect of martial arts, and Kanō embodies the dark aspects. They are opposites in every way, personality and appearance-wise, yet they are also very similar in that both are students of multiple Master-class fighters and partly because of this, they are viewed as the best fighters in their individual peer groups.
Prince of Tennis has a few as well. Fuji originally did not care as much for winning as enjoying the thrill of the game. Shiraishi, on the other hand, finds his own tennis boring but is committed to winning no matter what. Both are also considered the most formidable members of their respective teams, even more than their captain/lancer.
Kira is this to Light, becoming all the things he claims to hate, even as he's punishing the world for being them.
L and Light have a whole reciprocal shadow thing going. Light is the social one, who not only understands but really cares about proper socialization and not being indecorous, but as Kira he's also the one who's the most prolific serial killer in history. L is antisocial and willfully unsocialized, and he doesn't really care about a little thing like illegal detainment, mock executions, and torture, but he's the one trying to enforce the you don't go around killing people, and he means it. Enough to be unwilling to test the Note. They're certainly both liars. The primary difference between L and Light - two childish geniuses who hide behind their claims of justice and have no idea how to be wrong - is that L is capable of accepting and coping with his own and the world's flaws, two concepts that Light will never even grasp.
Big Bad Shishio is the assassin who succeeded to Kenshin. He represents what Kenshin could have become if not for a certain incident in his past.
Seta Soujirou is the naive, emotionless killer to Kenshin's Obfuscating Stupidity cheerfulness and paficism. They're both heavily influenced by the ideals of their respective masters, but while Kenshin eventually learned from his experiences, Soujirou was only ever guided by Shishio's ideals.
Saitou Hajime is the ruthless Anti-Hero to Kenshin's atoner. Like Kenshin, he operates on his own sense of justice and does what he thinks is right. However, he's willing to kill for his beliefs and doesn't believe in people changing in spite of his changing affiliations of over the years.
To Aru Majutsu no Index: Besides Accelerator, Tsuchimikado Motoharu serves as the Anti-Hero counterpart to Touma. Despite his good intentions, he is almost always willing to take more deadly measures to achieve things. While Touma has no organization affiliations, he tries to help any of his friends regardless of their loyalties. Tsuchimikado has multiple affiliations but is only really loyal to his younger step-sister. While Touma's Blessed with Suck powers are played for laughs, Tsuchimikado is in danger of dying from using his powers.
It's shown that Kotetsu and Kriem both had very similar histories. Both were NEXT that grew up during the height of NEXT prejudice and had come to hate themselves before encountering someone that inspired them to embrace their abilities and follow in their new idol's footsteps. The key difference is that Kotetsu's encounter was with Sternbild's first superhero Mr. Legend, while Kriem ran into NEXT-supremacist supervillain Jake Martinez.
A self-example: it's revealed late in the show that Mr. Legend, particularly near the end of his life, was nowhere near as much of a hero as people believed he was.
The protagonist Rock serves as a shadow for later character Yukio, who chose to take leadership in her yakuza family not that she had much choice. Later, Yukio even calls him out on his motivations for saving her, citing that he only sees her as his old self, but is unwilling to let go of his past.
Within the main cast are Rock and Benny. Both are among the nicer members of the Lagoon Company and aren't much for physical confrontations. But while Rock still (mostly) has a sense of morals and wants to save others, Benny has become completely desensitized to the violence that his fellow Lagoon members commit.
This is the entire premise of Yu-Gi-Oh! (well, besides the card game) and was the whole plot of the beginning manga. There are three doubles: one of the main character and two of the main antagonists, respectively. For the main character, Yugi, his double, which in the American fandom is called a yami ("darkness") evolved into a protagonist, but is still a Darker and Edgier version of Yugi. The antagonists are a classmate of Yugi's whose body is taken over by a vengeful spirit (the second yami) and a revenge-obsessed teen with an actual Split Personality (the third). A good deal of conflict in the series revolves around the magic of the Shadows wielded by them and others.
Fairy Tail has Jiemma, guildmaster of Sabertooth, where only the strongest wizards are allowed and failure is not tolerated. His mentality is very similar to Laxus's way of thought before he Walked The Earth and Tamed His Anger.
In Bleach, the Inner Hollow is Ichigo's true Zanpakuto spirit Zangetsu. Treating it as an invasive parasite instead of merely being his more aggressive side manifested is one of the reasons his power has fluctuated throughout the series. In the final arc, he at long last accepts that it along with the manifestation of his Quincy heritage the Old Man are not his enemies or his allies — they are him.
In Fruits Basket, Tohru is an incredibly sweet and selfless girl who always puts others before her own happiness. Akito is an angry emotional and mental mess who selfishly clings to the Zodiac curse, out of fear of rejection. While Akito envies the unconditional love Tohru receives, Tohru herself has deeply-repressed selfish urges (mainly her desire to have her mother all to herself, hating her father for "taking" her mother even though she knows such hatred is wrong). Over the course of the manga, Tohru comes to terms with the idea that it's okay to be selfish once in awhile, and Akito is able to let go of the curse, believing that there will be people out in the world who will still love her.
Major Batman villains are sometimes presented as Shadow Archetypes for the Caped Crusader, Depending on the Writer (especially ones that focus on his myriad psychological issues):
The Joker, in obsession and madness, in a case of Not So Different. This is explored by Alan Moore in Batman: The Killing Joke, where the Joker tries to turn Commissioner Gordon insane by putting him through "one bad day". In the end, when Batman confronts the Joker, the Joker says, "You had a bad day once, am I right? ... I can tell. You had a bad day and everything changed." This is all while we see what could be the Joker's origin. The whole thing ends with Batman and the Joker laughing together at one of his jokes about two guys in a lunatic asylum.
Two-Face, in his origin and obsession with double identities and justice.
Catwoman, fellow master thief/spy using a motif of an animal associated with the supernatural and the night.
Ra's Al-Ghul, in his aim to make the world a "better" place.
Scarecrow, in using fear to manipulate.
The Riddler, in leaving clues instead of finding them, with a need to prove that brain beats brawn.
Prometheus and the Wrath are entirely explicit about being Batman-driven-to-villany-when-parents-killed-by-cops.
Hugo Strange, Trying to understand the mind of a criminal in order to reach a goal.
The Captain America parallel is made rather explicit in the JLA-Avengers crossover. While Cap and Superman are set as the opposing team leaders, it's Batman who gets the We're Not So Different match, as they prove evenly matched in skill and intelligence, and decide to set aside the fight to figure out what's really going on.
To a lesser extent, Deadshot, Catman, the original Black Mask, and Jean-Paul Valley as Batman can also be seen as shadow versions of Bruce Wayne.
Even the Ventriloquist, with the fictional persona overshadowing the real human being.
Mr. Freeze who lost his loved ones in a terrible day and cannot reach other human beings...
From X-Men: Sabertooth is what Wolverine would be like if he ever fully embraced his berserker side. Cassandra Nova is Prof. X's shadow archetype, being his evil twin that was killed before birth.
Aquaman had an explicit Shadow Archetype in the Thirst, which was the dark side of his then-newfound Waterbearer abilities; As his mentor the Lady of the Lake put it, "he is you Arthur".
It's also in this same series that Batman is established as the clearly defined opposite of Superman, the pair taking roles previously held by Hades and Apollo.
The Sentry and his nemesis/other-half, the Void are a pretty literal example given the Void's appearance and the nature of their relationship.
Nega-Scott of Scott Pilgrim. In the true Jungian tradition, Nega-Scott represents everything about himself that Scott doesn't want to deal with, both his flaws and his true potential as a better person. It doesn't help that Gideon tampered with Scott's memories, repressing Nega-Scott even further. It's only after Scott and his shadow confront each other that he can grow up fully.
Spider-Man has several. The Scorpion while not so much in personality, being a crazed villain, still has arachnid-based powers and costume. The Green Goblin, who has similar strength and agility, shares Peter's sense of humor and love of adventure. Venom has many of Peter's powers, and represents what he would have become if he hadn't had the will to resist the symbiote. Kaine is Peter's defective clone. During JMS's run on Spider-Man, we met Ezekiel, who had all of Spider-Man's powers but lacked the courage and determination to be a hero (he's also one for Uncle Ben in a way). Then there is Doc Ock, who was also bullied and gift for science. He is what Spider-man could have easily became if he let his powers go to his head.
Ultimate Spider-Man takes Venom's role as this Up to Eleven, as they basically had the same backstory, only Eddie didn't have a loving Aunt and Uncle after his parents died to steer him on the right track.
Baron Mordo to Doctor Strange, who represents what Strange might have become if he hadn't learned humility, patience, and respect for others. Doctor Strange: The Oath introduces Nicodemus West, yet another student of the Ancient One, with the added resonance of also being a physician.
As with Batman, many of Superman's nemeses are dark reflections of himself:
General Zod is Superman with a sense of personal entitlement instead of charity.
Mr. Mxyzptlk is an "alien" who is "careful" with his immense power but still uses it frivolously instead of responsibly.
Doomsday is all the power harnessed for destruction instead of protection.
Brainiac, being the malevolent planet destroying alien to Superman's benevolent alien.
While not created as a Superman villain, Lobo has been used as Superman's shadow as well: both are comparablly powerful, both are the survivors of a dead race (Lobo killed his race while Superman's was dead before he was old enough to know them) but Lobo does whatever he wants and leaves a path of desctuction behind him.
Lex Luthor sees Superman as his own Shadow Archetype: Lex sees himself as someone who's worked and struggled for everything he has who represents the best humanity has to offer, and he sees Superman as someone who never had to earn his powers who sets himself above humanity and lords it over us. Furthermore Superman uses power for the good of mankind, while Lex would use his fortune and influence just to show how powerful he is. Superman grew up with a loving family, while Lex's were abusive and were killed(possibly by him).
Darkseid is what Superman would be if he decided to use his powers to be a God ruling over everyone.
Red Hood, to Batman. After being revived, Red Hood trains with the All-Caste, a secret, somewhat mystical sect of warriors who mirror Batman's League of Assassins. Red Hood is also Crazy-Prepared like Bats, with safehouses around the globe, each one full of weapons and supplies.
Starfire to Superman. She's the flip side of Clark's coin, both being nearly all powerful aliens that are powered by the yellow sun. Both came from being traumatically removed from home into unfamiliar surroundings, with two very different upbringings. Starfire's perceptions of humanity, along with her tendency to attempt to kill whatever she doesn't like directly contrast Clark's. Star wishes to remain very private, only presenting herself willingly to the public eye when it's unavoidable. She doesn't wish to come off as friendly or there for others' protection, she just wants to do what she wishes. In issue 14, they meet... and it nearly breaks out into all out brawl involving the "team" and Sups, mostly due to her and Jason's character traits. It takes Jason's date, Isabel, from keeping things from getting out of hand while getting them all to sit down and talk.
In the recommendedSlayers fanfic Slayers Reflect every character meets a "reflection" of them.
One of Stray's major themes is "What can change the nature of a man?" The protagonist, Adamska, has two shadow counterparts within the story who represent different variants of himself-gone-wrong. One is an older version of himself that represents everything he doesn't want to become and the other is a former Tykebomb raised by the setting's Ancient Conspiracy as a successor when Adamska himself broke free of their control.
In keeping with the Shinji/Gendo dynamic mentioned above, Shinji And Warhammer 40 K makes the comparisons between the two quite explicit, which Shinji fervently hopes to avoid coming to pass. Ritsuko even goes as far as to label Shinji "mini-Gendo".
JLA Watchtower[-/=]DC Nation - the "Strangers" plot. Dark Angel "swapped out" several Titans with Evil Counterparts, and twisted reality so that the feelings people had towards the "replaced" Titan went to the villain instead. Nastiest in the case of Cheshire and Troia, but also pretty bad with Starfire's husband and a creepy shapeshifter, and between Fauna and Terra.
Also in the Dark World, the Valeyard, the Doctor's discorded self, is this to the Doctor himself. He possesses all of the Doctor's negative traits (his ego, his manipulative abilities, and even a full on Time Lord Victorious power trip), but none of his positives. Also, where the Doctor has faith in his companions, the Valeyard believes allies only hinder one's progress. While the Doctor has on many occasions been willing to sacrifice himself to save others, the Valeyard seems absolutely terrified of permanently dying. He also notably is a Chess Master, but doesn't seem as good as the Doctor when it comes to performing an Indy Ploy. Fitting, as the Valeyard was explained by the Master in the original series to be the personification of the Doctor's inner evil and darker qualities.
Getting Back on Your Hooves: Checker Monarch Trixie's sinister sister is this to Trixie, showing what The Great and Powerful Trixie could have been if she hadn't seen the error of her ways. This is show most directly when Checker infiltrates Trixie's dreams and assumes the form of The Great and Powerful Trixie. It's only by admitting that she was like that and that she's changed for the better that allows Trixie to defeat Checker and finally be happy with herself.
Films — Animated
The Lion King: Scar could be considered Simba's Shadow Archetype in Jungian terms: he is an adult with young Simba's headstrong and cocky nature and immature understanding of what being king means ("I'm the king, I can do whatever I want"). The plot is only solved when Simba defeats Scar, removing from himself his childishness.
Superman: Doomsday features Superman's clone, who still holds Supes' desire to help people and protect his city, goes into extreme measures to do so, from threatening civilians to killing Toyman. Superman even calls him "My reflection in a cracked mirror."
Wreck-It Ralph has Turbo, a character from another game who, like Ralph, felt unappreciated about his status in the arcade. However, Ralph's adventure outside of Fix It Felix Jr.'s is motivated by an innocent need for approval. Turbo is driven by his obsession for recognition. Ralph doesn't intend to harm anyone and sneaks into a neighboring videogame simply to win a medal, whereas Turbo is responsible for the destruction of his home world, another nearby video game, and the reprogramming and enslavement of the Sugar Rush world. Turbo's pursuit of respect and acknowledgement mirrors Ralph's, but he is shown as willing to destroy anything that opposes him to get it.
First we have his mother. While they both saw that dragons weren't the monsters others that others thought they were, Valka gave up on trying to change Stoick and the other Berkians and left to love with dragons for roughly two decade, adopting a Humans Are Bastards view and trying to keep dragons and humans apart. Hiccup, on the other hand believes that people CAN change for the better, and didn't give up trying to change Berk (and his father's mind) for the betterment of both humans and dragons, and succeeding.
Secondly we have Drago, the Big Bad of the film. Hiccup uses The Power of Friendship to train dragons, Drago controls them through intimidation, torture and Mind Control, courtesy of his Bewilderbeast. Hiccup trains dragons by approaching them and laying his hand on their face, Drago stomps on them with his boot. Hiccup has a pegleg, Drago's missing his left arm. Hiccup works with Toothless, Drago just shouts orders.
Films — Live-Action
The titular Black Swan is everything the protagonist is repressing.
In Lord of the Rings, Gollum is a vivid reminder of what Frodo could turn into if he gave into the ring.
Harvey Dent and Batman of The Dark Knight are shadows of each other - both had a day where they lost the people most important to them, which changed their lives forever. The difference being that Rachel Dawes was there to push Bruce back into believing there's good in the world worth fighting for, whereas for poor Harvey there was just the Joker showing up to mess with his head some more.
Darth Vader was this to Luke, especially in the second and third movies; both of them dressing in black, losing a hand in battle etc, and the family connection only added to their similarities. The prequel trilogy tried to emphasize them further by giving Anakin's backstory parallels to Luke's. Luke was even offered a chance to turn to The Dark Side; the difference between Vader and Luke was that Luke opted to remain in the light.
In the first film, the nearest thing Luke has to a shadow is Han Solo. Luke is young and naive, empathic, believes in the Force, and is a great pilot; Solo is Older and Wiser, self-centered, a Flat Earth Atheist, and is also a great pilot.
The villains in the prequel trilogy (with the exception of Palpatine, perhaps the shadow to Yoda) are reflections of Anakin Skywalker/Darth Vader:
Darth Maul, a young, extremely skilled and powerful Sith apprentice. Their similarities are further shown in The Clone Wars animated series, where he returns from a near-death situation with prosthetics.
Count Dooku, a former Jedi who left the Order due to disagreements in philosophies.
General Grievous, a twisted mixture of machine and man which causes problems in breathing and combat.
The battle droids, mass-produced and programmed machines, to the clones, mass-produced organics who are also programmed to some degree.
Fight Club: Tyler Durden is the Shadow Archetype to The Narrator, considering that he is nothing more than The Narrator's alternate personality, comprised of what The Narrator wants to be, but can't, because of the pressures of society. For Hollywood, this makes him an unusually Jungian version - he's what is repressed, not what is evil.
"I look like you wanna look, I fuck like you wanna fuck. I am smart, capable and, most importantly, I am free in all the ways that you are not."
Ironically, Shiwan Khan in 1994 The Shadow movie is this to the titular protagonist, The Shadow himself. He got the same training as The Shadow, has same powers and is a big fan of Shadow's former self, ruthless crime lord Ying Ko.
Adaptation: Charlie Kaufman's (fictional) twin brother Donald functions as his shadow, embodying everything Charlie dislikes about his profession and doesn't want to become. In true Jungian fashion, however, there are positive aspects to his character as well, which Charlie's neuroticism and self-awareness lead him to suppress, and which he ultimately grows as a person by accepting.
The Avengers: Loki works as a twisted mirror to the Avengers more than once. He's an example of different parts of their personalities, like Thor's values about becoming King, the Widow's past murderous life or Tony's Big Ego, gone wrong.
Skyfall's villain Raoul Silva is a former MI6 agent (and a brilliant one, according to M), who is what James Bond could easily become. He even points this out multiple times over the course of the film, and the other characters aren't arguing with him, especially given that M leaving Silva for dead in China has echoes of her risking Bond's life at the beginning of the movie.
Silva: We are the last two rats.
Sherlock Holmes has Professor Moriarty: Holmes's equal in every way but dedicated to crime.
In the fantasy novel A Wizard of Earthsea, the main character Ged accidentally raises an evil spirit representing the darkness in himself, which is actually called the Shadow in the book. It follows him everywhere until he can call it by its true name—Ged.
In the Ghibli animation, the shadow is rather confusingly characterised. It opens the film by making him kill his father (from within), then doing nothing, then saving the love interest, then going without to try and drown poor Arren, then reappearing 'without' once more to save the day again and flirt with said love interest.
Gollum is the shadow of Bilbo and Frodo Baggins - and, to some extent, Sam. Remember all those conversations between Sméagol and Gollum that Sam spied and was utterly sick of hearing? Just when Sam and Frodo reach Mount Doom, what is Sam doing? Talking to himself about the futility of their quest!
"And then what, Sam Gamgee, then what?"
Sauron is to an extent the shadow of both Gandalf and Galadriel, while Saruman is a more specific shadow of Gandalf.
Gandalf: I am Saruman. Or rather Saruman as he should have been.
Frodo gets to watch several people confront their own Shadows when he offers the Ring to them. (The ever-humble Sam, notably, sees his Shadow — a mighty hero — when he becomes Ringbearer, and consciously rejects it.)
Esme and Lily Weatherwax (complete with lots and lots of mirror imagery), Angua and Wolfgang von Uberwald, Moist von Lipwig and Reacher Gilt (arguably), and Vimes has his Beast, which he sees in many of the worst criminals he faces. Carcer is another example of a shadow archetype for Vimes: Where Vimes spends all his time controlling his inner monster, Carcer indulges the Beast to the fullest extent.
Death gains one in Reaper Man, when he is replaced and made mortal. This "New Death" lacks his respect and compassion for mortals, instead seeing itself as a ruler, not a caretaker.
Voldemort and Harry share many things, but the most important might be that both had a hard time when they were children and had their lives completely turned around when they discovered the world of magic. But if Harry found friends and love, Voldemort found a way to gain power. The Not So Different speech is often given with these two.
Severus Snape could be considered a shadow to Voldemort. Both ambitious, magically-gifted, halfblood, lonely young men from uncaring families, both fascinated by the Dark Arts, both fashioned a fancy name (The Dark Lord, The Half-Blood Prince); Snape could easily have been (and for most of the series seems to be) a Voldemort In The Making. Ultimately it may be Voldemort's greatest weakness that keeps Snape from becoming a Dark Lord in his own right.
In the sequel to Chocolat, The Lollipop Shoes, Zozie de l'Alba is Yanne's shadow, everything about herself that she has repressed - her magic, her glamour, her bohemian lifestyle, her free-spirited ways - as well as her impulse to use her magic to influence and control others.
In the works of Douglas Preston and Lincoln Child, Aloysius Pendergast has a shadow in the form of his brother Diogenes. Both are utterly brilliant, masters of disguise, and experts in numerous fields; Diogenes, however, suffered a childhood trauma which drove him quite mad.
Charles de Lint has the formation of actual Jungian Shadow Archetypes be an actual thing that happens in his Newford setting. One story revolves around the young woman who is the shadow of a recurring skeptic character; he cast her off at some point in childhood and no longer is aware of her, and she has identity issues. Eventually concludes she can be her own person, having been independent ever since she was cast; honorable mention to a conversation she has with a mentor figure:
Mentor: I once met the shadow of a man who was on death row for murder.
Christmas: What was he like?
Mentor: Meanest sonuvabitch I ever saw.
Christmas: I meant the shadow.
Mentor: Yeah, me too.
In The Girl Who Circumnavigated Fairyland... and its sequel, this is done with actual shadows that separate from their owners. The shadows are usually similar in personality to the originals, but tend to act with less restraint. The shadows of Ell and Saturday, for instance, still care for September as her friend, but do things like enchant her or kiss her trying to make her happy, without considering that she doesn't like having things done to her without her permission. Halloween, meanwhile, is much colder and crueler than September, but they do share some similarities as we see Halloween is willing to use her considerable power to rescue her father (the shadow of September's father). Inversely, we see that the shadow of Maude/the Marquess is considerably more subdued and kind to September than the original ever was.
A classic shadow pair is the good-yet-indecisive Kirk and his evil-yet-effective twin in the Star Trek: The Original Series episode "The Enemy Within": "I have to take him back... inside myself. I can't survive without him. I don't want him back. He's like an animal, a thoughtless, brutal animal — and yet it's me. Me." Really though, both the good and evil Kirk are Shadow Archetypes to the real Kirk; he wouldn't want to be either one of them.
Romulans are the shadows of the Vulcans, and on dimensional level, the Mirror Universe is the shadow of the Star Trek 'verse.
The Borg are shadows to humanity, being uniform and collectivist versus human individualism and self-determination. They also share several traits with humans, such as adaptability and desire for self-improvement, all of which they can do MUCH faster. They explore space searching for other forms of life, but while the humans of Star Trek wish to meet with other species peacefully to learn about them, the Borg learn by conquering and assimilating other life. Another parallel is mentioned by Eddington in Deep Space Nine, pointing out how the Borg state their plans for assimilation, while humans slowly manipulate races into joining the Federation.
Shadow pairs are very common on Buffy the Vampire Slayer, where they are what the good character could have been if they'd gone wrong. Faith is Buffy's shadow; Ethan is Giles's shadow; Adam is Riley's shadow. Vampires are sometimes seen as the shadow of the people they were when alive. Some characters manage to be their own shadows: Angel, Willow, Oz, Spike, and (in one episode) Xander. Willow's shadow, the vampire from the Wish Dimension, gets extra points - not just dangerous and creepy, but also showing signs of Willow's latent sexuality. Jonathan is what Xander might have become if he'd made a few wrong turns.
Similarly, the Miniature Killer (and her presumably-incestuous foster father Ernie Dell) are shadows of Sara and Grissom on CSI: Crime Scene Investigation. The Miniature Killer represents everything that Sara and Grissom are unwilling to face about Sara's past and her consequent incompleteness as a person.
Boober Fraggle came into conflict with the fun-loving, irresponsible part of his personality, which manifested as his Evil Twin Sidebottom (the side of himself which he keeps on the bottom). It wasn't until Boober accepted Sidebottom as a part of himself that he was able to make his Evil Twin go away.
Lively, enthusiastic Red met her own opposite — the modest, cautious Beige — when the Fraggles encountered another colony of their species.
Elle Bishop and Claire Bennett - it's explicitly mentioned by the resident Magnificent Bastard that he protected Claire from the company because he didn't want her to become Elle.
Sylar and Peter Petrelli have been explicitly described by Word of God and the actors, as two sides of the same coin, with similar powers and desires to be special. Sylar's method just involves a lot more blood and crazy.
The Master is this to the Doctor, with all of his arrogance, superiority and passion for meddling augmented with megalomania. The new series at several points makes it explicit that it would be very easy for one to become the other.
The new series frequently contrasts the Doctor with himself and what he could become. Especially in "Amy's Choice", with the darker self showing the Doctor's wishes for control, power, and interestingly, his own self-hatred.
The Valeyard is a more literal example, as he's explicitly stated to be the Doctor's inner evil and darkest qualities personified.
Tony's second series episode of Skins is a study in Jungian psychology; Sean Pertwee's character(s), the crazy dude on the train and the admissions counselor at the university, together form Tony's shadow (Tony explicitly describes himself as "<the counselor>'s bad dream, him before he was destroyed by the system").
The Vorlon race and its shadow counterpart, the, er, Shadows. The series starts off with the standard depiction of the Shadows as evil, but then shows that in a different way Vorlons are evil too. Both the Vorlons and Shadows are ancient races who remained in this galaxy to guide and help younger races develop. The problem is the Vorlons believe development from strict order and control. The Shadows believe in development from the chaos found in survival of the fittest. They were supposed to work together, but they got into a pissing contest about who was right, and forgot why they were left in the galaxy in the first place; they leave in shame when the younger races remind them of this fact and tell them to get lost.
Garibaldi faces his own darker side, in a way, in season 4. He was captured by a telepath named Bester who wanted him to find an anti-telepath conspiracy. He didn't have Garibaldi's personality wiped, but enhanced Garibaldi's paranoia and dislike of authority to the point Garibaldi left his job, his friends, and betrayed one all for the sake of this mission.
Then there is Londo Mollari and Lord Refa. Refa initiates Londo`s darker side extremely well. Only after his heel realization does Londo consciously try to get rid of him.
Dexter's whole shtick is that he kills people who represent what he would be if he didn't have a code. So, in effect, he has killed hundreds of manifestations of his Shadow Archetype. On top of that, every season introduces a new mentor-type figure who presents a more personal version of the archetype.
House and Wilson. Wilson's cheerful Nice Guy personality is, at least in part, a deliberate persona he puts up because he doesn't want to be hurt by rejection. House's abrasive Jerkass personality is, at least in part, a deliberate persona he puts up to prop up his ego (thus preventing himself from being hurt by rejection). Both frequently note that the reason they're such good friends is because the other allows them to release a little bit of what they hide from everyone else, and because both can see right through each other.
In one episode, a man became his own shadow when he had a neurological problem that caused him to spout whatever came into his head.
A less serious example on Friends is Mr Heckles and Chandler. They both started out as witty jokesters, but avoided getting close to anyone. The difference was Mr Heckles never overcame his issues and died alone, while Chandler learnt from his example and thanks to his friends, built meaningful relationships and eventually fell in love.
In SmallvilleLex Luthor was always being warned about the darkness that he carried within himself. Enter Lx-3, a failed clone of Lex in the Season 10 premiere, "Lazarus". Lx-3 was essentially Lex without the facade, with all the rage and anger simmering at the very surface. An Axe Crazy psycho to Lex's Manipulative Bastard, Lx-3 showcases exactly what is lurking beneath the surface of our favourite Corrupt Corporate Executive, while demonstrating how vital that restraint really is if Lex is to be a successful supervillain.
In the BBC's Sherlock, Jim Moriarty, the "consultingcriminal", is an even more direct Shadow Archetype to Sherlock Holmes than the original literary character was. Like Sherlock, Jim is phenomenally clever, unfettered and easily bored with everyday life. But unlike Sherlock, who solves crimes and puzzles, Jim staves off boredom and puts his brain to the test by masterminding perfect crimes on behalf of wannabe criminals. He represents what Sherlock could become someday, and shows just how important Sherlock and John's friendship is in pushing Sherlock towards being heroic and doing the right thing.
Morgana is this to Merlin post-Face-Heel Turn. She's done a lot of the immoral things he's done (killing innocents, betraying friends, choosing loyalties) but while he avoids them until he has no choice, she does them with an almost sadistic relish. Her Freudian Excuse is also one of the key parts of his Conflicting Loyalty (they are magical in a kingdom that fears magic).
The Wild Wild West: Why is an Diabolical Mastermind like Depraved Dwarf Miguelito Quixote Loveless is so obsessed with a lowly paid Secret Service Agent like Jim West, to the point of purposely adding him to all his world conquest schemes (and ensuring Failure Is the Only Option)? Both of them are intelligent (but Loveless is a genius), handsome, and have a lot of success with the Girl of the Week. Loveless will never accept that Take Over the World would result for him in And Then What? situation; he'll still be the same bitter man. Trying to destroy West, the man who reminds Loveless that being shorter than anyone else is not obstacle to happiness, is his true dream.
Jackman and Hyde in Jekyll, just like the source material.
The Shadow is an integral part of Wraith: The Oblivion. Your worst enemy, who's always with you, tries to manipulate you into falling into oblivion... and everyone has one. Even worse, the standard approach is to have the players play each others' shadows on the side, leading to a whole deal of sneaky backstabbing.
The Ravenloft setting had a monstrous device called The Apparatus which could split any character into two opposing personalities (it could also turn two people into one). The only way to undo it was to get them both back into the machine and run it again in reverse.
The mirror of opposition. Any character who gazes into the mirror will create an identical twin of opposing alignment, with identical levels, skills and equipment.
The Ebon Dragon. One of his titles is "the Shadow of All Things", and he exists to oppose heroism wherever it may exist and corrupt it into villainy. Which just leads to layers of complexity, when one considers that the Ebon Dragon instigated the creation of the Unconquered Sun to provide him with an overarching 'light archetype' to define himself against. This resulted in the emergence of Five Days Darkness... best described as the Unconquered Sun's Shadow Archetype, and effectively the Ebon Dragon's grandchild.
The Abyssals are presented as being narrative Shadow Archetypes of what the Solar Exalted might become, now that they've returned... while the Terrestrials are easily used as a narrative Shadow Archetype for what the Solars had become when they ruled the world; oppressive tyrants that must be unseated.
There's a very powerful (Solar Circle Sorcery) magic spell with a similar effect to the mirror of opposition above, with the twist that the original is trapped in the mirror while their Evil Twin runs loose.
The Imperial Guard and the Lost and the Damned are poorly equipped, poorly trained and have piss-poor morale note Relatively speaking, anyway. By modern standards they would be frighteningly powerful and competent., used as expendable Cannon Fodder by the higher ups with little or no regard for the horrific casualties they'll inevitably suffer. This is especially evident in the Gaunt's Ghosts novel The Armour of Contempt, where a Guard character is smack in the middle of human wave tactics that are identical to the one Chaos forces used in Necropolis.
Chuubo's Marvelous Wish-Granting Engine: Chuubo/the Wishing Boy and Leonardo/Nightmare's Angel. Both have constructed magical engines, but Chuubo wants to be normal apart from that and Leonardo has grabbed at specialness with both hands, even when it wasn't a good idea. Chuubo staves off loneliness by making friends (literally, in the case of Seizhi/the Best Friend), while Leonardo has abandoned friendship in order to better defend Town. Chuubo's memory is a bit cracked through mysterious past experiences; Leonardo may have deliberately erased his own. Both are Imperators of a sort, but Chuubo is a healthy if amnesiac one while Leonardo has been corrupted into a Mimic. They're even depicted in artwork with similar hairstyles, although Chuubo's is wavy, unkempt and stops above the eyes while Leonardo's is straighter and has Peek-a-Bangs. There's a lesser shadow-archetype pairing in Billy Sovereign and the Best Friend, who have very similar stats and Arcs, and are both Actuals, although Seizhi has a soul and Billy does not, but given that Billy once impaled Leonardo on a railroad spike, that probably crosses over into full-on Evil Counterpart.
Star Wars: The Old Republic: Most of the characters are shadow archetypes to one another (Jedi Knight vs Sith Warrior). A more pronounced example is the relationship between the apprentices of both the Jedi Knight and Sith Warrior (Jaesa and Kira). Both have very similar personalities, but ultimately went different ways based on their relationship with Jedi. Kira had a mentor who was kind and supportive, and had seen the evil of the Sith. Jaesa had a master who was a hypocritical bully. As a result, Kira became a Jedi Knight while Jaesa became a Sith Apprentice.
Characters meet their Shadows in both Persona 2 games. There is much misery to be had as their doppelgangers air out character flaws to all in earshot, daring them to prove they have learned from or grown past these issues. However these are all just avatars for the one single collective Shadow of all humanity. In Eternal Punishment, neither Kei/Nate Nanjo nor Eriko/Ellen Kirishima meet their 'evil twins' in this way, but find corrupted people who they share common traits with - Kandori Takahisa in Kei's case and Chizuru Ishigami in Eriko's. Eriko also gets chewed out by a former classmate (actually another doppelganger) she has obsessed over locating.
Aigis and Metis in Persona 3: FES. Aigis is more reserved and introspective, while Metis is more impulsive and extroverted. It turns out that Metis is, in fact, a product of the Abyss of Time, created when Aigis locked away her human side after the Main Character's death in the original storyline.
Same goes in Persona 4 — all the main characters, except the Heroic Mime lead, encounter their inner Shadow Archetype at one point. These shadow archetypes follow the Jungian archetype and represent whatever the characters may have repressed. They will loudly exclaim these repressed feelings to the world, and do not take kindly to being denied. Accepting and embracing the flaws the shadow archetypes represent is how the party members obtain their persona, another call-out to Jung.
A non-shadow example of Shadow Archetype is the real killer, Tohru Adachi, who is a counterpart to both The Hero and Yosuke Hanamura. On the latter's end, they both suffer from Small Town Boredom, Yosuke merely repressing it until his Shadow spills the beans, while Adachi deals with the boredom by using murder for entertainment. With regards to you, both you and Adachi are both relatively recent arrivals who received their powers from the same goddess (Adachi's own persona is basically a palette swap of your starting persona), but only you use it for good. It's played up more in Golden, where your Social Link with him ("The Jester") is the reversed version of your own arcana ("The Fool"); you even both have a mutual fondness for magic tricks. But while you spend your time improving yourself and getting close to people, Adachi basically drifts through life and ignores opportunities which don't offer immediate gratification; basically, he's you if you didn't bother with the non-combat parts of the game.
Also from Atlus, in Catherine there is Shadow of Vincent, which represents all of Vincent's repressed fears of commitment to marriage and women in general, and is very similar to the Persona examples above, leading to the possibility of it having more ties to the Persona subseries than the other Mega Ten games.
BlazBlue's Jin Kisaragi has two shadows: Hakumen and Kagura Mutsuki. The former represents what Jin would be if not for the Yukianesa's influence (and vice versa), and the latter represents what Jin would be if he ever got over his deep-seated issues.
The player character is forced to fight a shadow version of themselves. The only way to damage it is with healing items.
Every character has a (class-based) Nemesis, who turns out to represent a corrupted version of that class. Seal Clubbers face a seal stronger and fiercer that any before. Turtle Tamers fight a Turtle Poacher. Pastamancers, who control Pasta Spirits, fight a pasta spirit who no one can control. Saucerors, who allow The Sauce to flow through them, fight a blob that was rejected by the sauce. Accordion Thieves fight an angry mariachi, and Disco Bandits fight the Spirit of New Wave, the genre which killed Disco. In mid-2009 brief encounters with the Nemesis became possible, and as of early 2010 it's possible to complete the full side-quest against the Nemesis, complete with a secret Island Base (with volcano!) and the Nemesis possessing a One-Winged Angel form.
Devil May Cry has one in its 3rd game. One of the final bosses (the last faced before the Boss Rush) is a shadow version of Dante. When it first confronts him, Dante demonstrates an oddly adroit knowledge of literature and culture (pointing out that the Shadow typically represents aspects of themselves the hero must overcome) before defaulting to his typical persona.
"I know why you're here. You want to ask me some questions. Well too bad! I've already answered them myself. I don't need you. Get lost, you poser."
Word of God for Ni GHTS Into Dreams is that NiGHTS is supposed to represent the Shadow Archetype. However, the character is an aversion of the "Always Negative in Fiction": NiGHTS, while somewhat mischievous, is definitely not evil... at least, not during the events of the game. It's said that NiGHTS was created by the Big Bad, Wizeman, as a helper. He/she/it instead embodies positive traits that are buried in the protagonists due to their problems — freedom, courage, self-confidence, etc. And NiGHTS has his/her own shadow archetype: Reala, a servant to Wizeman.
In Tales of Symphonia, Mithos seems to fit this trope with Lloyd, both having much the same origins, but the latter not becoming the former by willing to accept one's own mistakes.
Mithos: Farewell, my shadow, you who stand at the end of the path I chose not to follow.
Silent Hill - From the second game on, the hero and antagonist are more or less shadow archetypes of each other:
Ryu's "evil" side (more like unrestrained) from Street Fighter, the result of Ryu letting go of his humanity to win at any cost. Akuma wants to permanently draw this out of him while Gouken (Ryu's master) teaches him that this is not the way of the warrior. In the actual canon of the story, this is more metaphorical than realized (Ryu never rampages around in his dark side, though he is always afraid it will get the better of him) but some games do allow the player to use this version of Ryu.
Commander Shepard racks up five of these throughout Mass Effect:
Saren Arterius, Big Bad(not) of the first game, much like Shepard is an elite soldier who bands together an elite squad to deal with the Reapers. Saren chooses to side with the Reapers in hope of being spared while Shepard is out to defeat them.
Tela Vasir is an Asari Spectre who Jumped Off The Slippery Slopeby allying herself with the Shadow Broker. If called out on her Moral Event Horizon, Vasir will throw back in Shepard's face how s/he's also willing to work for a morally questionable organization (Cerberus).
Kai Leng, who like Shepard, are both former N7 operatives and the best fighters of their respective organizations (Alliance/Council for Shepard and Cerberus for Kai Leng).
Javik, the first non-villainous version of this, is the Prothean version of Shepard who failed in his mission to stop the Reapers. During the last Cycle, he watched his homeworld burn, saw his team get indoctrinated and lost the War. As a result of both this and his people's cultural norms, he's taken a rather Social Darwinist philosophy.
The Mysterious Figure from the Citadel DLC for 3, who is later revealed to be a Cerberus-created Clone of Shepard. Part of their hatred towards the real Shepard stems from having been created solely for spare parts if they were badly injured, never even supposed to have been conscious at all. Their goal is to Kill and Replace the real Shepard, but since they lack the original's memories, have been forced to hack information from multiple government databases to try and steal their identity. Clone!Shepard is shown throughout to be a Bad Boss, a human-supremacist and extremely arrogant, simultaneously jealous and dismissive of the real Shepard's feats and accomplishments, as well as the loyalty they instill in their allies.
In Mass Effect 2, Mordin is a scientist who struggles with the guilt of unleashing a virus that reduced the fertility rate of a species, in order to save the galaxy from them. During his loyalty mission, you meet Maleon, another scientist who represents what Mordin would be if he let his guilt overtake him and Jumped Off The Slippery Slope.
Alex Mercer of Prototype has... Alex Mercer. Or rather, the real Alex Mercer and the Blacklight Virus as Alex Mercer. Both are ruthless, cruel in their methods, and quick to destroy those who get in their way or cross them... but while the real Alex Mercer truly was completely selfish and sociopathic — trying to take his deadly enhanced Blacklight virus as a bargaining chip to buy his safety from a purge of his company, then releasing it out of spite when that failed, despite his sister living in the city — the Blacklight Mercer actually has some capacity for compassion and kindness. He fights to protect Mercer's sister where the real Mercer was willing to let her die. His fight, although selfish initially, helps save Manhattan and improve things for the innocents caught in the crossfire between Blackwatch and the infection. And in the end, he risks his own life to save Manhattan from nuclear annihilation. Whereas the real Mercer sacrificed his conscience and morals out of self interest, an initial motivation of self interest causes the Blacklight Mercer to develop a conscience and morals.
In one way or another, Oersted of Live A Live manages to shadow almost every other protagonist in the game. (Pogo's desire for love saved him, while Oersted's desire for love damned him, Masaru strengthened his body and soul, while Oersted strengthened his body at the expense of his soul, and so on.) The only exception is the nameless martial arts master—Oersted instead shadows his students.
Dark Pit of Kid Icarus: Uprising is an example of this, actively defying the Evil Twin trope by manifesting some of Pit's positive repressed traits, such as the desire not to be a pawn of the gods (including the evil goddess who created him).
In fact, the Dragonborn DLC introduces another Dragonborn who gives in to these impulses.
In Bioshock Infinite Booker and Comstock are nearly perfect parallels and anti-parallels. A lone anti-hero revolutionary, a monstrous leader of a religious nation. Both at the brutal massacre of Wounded Knee, and other historical parallels. They're Alternate Self versions of one another. Booker is the man who rejected baptism as false redemption, Comstock is the man who accepted it... and ignored redemption.
Shirou from Fate/stay night has two main examples. Firstly, there is Kotomine, a man who has exactly as much a sense of self but can only find meaning in hurting others where Shirou can only find meaning in helping them. Secondly, there is Archer, the embodiment of Shirou's Wide-Eyed Idealist ideals of becoming an 'ally of justice' who'll always try to save everyone; said person hates what he's become and wants to kill Shirou to wipe himself from existence or, at the very least, save Shirou from destroying himself.
Probably Jadesprite to Jade, seeing as Jade is optimistic despite the future not looking too good while Jadesprite believes everything is doomed and won't even listen to a "the future's worth fighting for" speech. Jadesprite's hysterics drive Jade from a get-ahold-of-yourself-man-slap to assault. This is eventually lampshaded by acting-psychiatrist Karkat.
A Dark Is Not Evil example is Karkat to John. Both have similar rooms, fulfil similar roles in the plot, and use weapons with a symbolic similarity (John uses a hammer, Karkat uses a sickle). However, their personalities are quite different - John is sweet, mischievous and innocent, and Karkat is bitter, angry, but rather wise. John types in all lower-case, but Karkat types in ALL CAPS. And while both of them love terrible movies, John just has really bad taste and defends the quality of the films he loves - Karkat is aware his favourite romcoms are terrible, but loves them passionately anyway. This is one of the reasons why Karkat, at one point, falls in hate with John (and also one of the reasons why John doesn't reciprocate).
During the Syrup Village Arc, a parallel is created between Natalie and DM, who respectively play Nami and Kurahadol. Natalie lives by the Rule of Drama, and created Nami with a complex Backstory that makes her hate pirates. However, she's still fully capable of working together with the group while keeping Nami in-character. DM, on the other hand, makes absolutely no effort to intergrate with the others, having Kurahadol blantantly bait and insult them, then refusing to apologise in or out of character. (Unless you count her stating "That's just how he is," acting like it's the others fault for not being able to put up with him.)
Later in the same arc, another parallel with Luffy's player Luke is revealed: both are all about having fun. However, while Luke enjoys playing with his friends and doesn't care whether they 'win' or 'lose', DM only cares about her personal enjoyment. It simply doesn't matter that her preferred gaming style constantly screws over everyone else, so long as SHE's having fun.
Female alter-ego Danni brings out aspects of Daniel's personality that Daniel might not otherwise acknowledge. In particular, her rant at Rebecca for betraying their relationship is something Daniel never would have said, though he had doubtless been carrying those feelings around for years.
Subverted by Evan and Eva, who actively embrace their personality split; the alter egos will trade off situations between them, depending on which one is better suited to handle the task at hand.
Played straight with Victor, who has pushed all of the aspects of his personality that troubled him into his "Dark Place" — inadvertently creating a rage-fueled monster that he is no longer able to control.
On Samurai Jack, Aku used a spell to create a Shadow duplicate of Jack. Aku theorized that Jack could not defeat himself in combat, which proved to be true. Jack prevailed by becoming peaceful and calm, proved his mastery over his own anger and drew the Shadow into himself
Shego is Kim Possible if she got bored of being good. She's also a shadow of her brother Hego, who is a superhero.
Red X and Slade are both Robin's shadows — X represents what Robin could become if he decided looking out for himself was more important than helping people, while Slade represents what could happen if Robin gave in to evil completely (as Slade is an Evil Mentor, he's also a shadow of Robin's actual mentor, Batman).
Though it isn't really played up, Terra can be seen as Raven's shadow. Both are Dark Magical Girls with powers tied to emotions, but Raven practices intense self-discipline to keep herself on the good guys' side, while Terra is an emotional wreck who doesn't really mean evil, but turns out to be very susceptible to serious temptation the first time it comes down the pipe. Raven calls Terra out on how much she has to work to control her powers while Terra won't take that responsibility.
To a lesser extent, Raven and Jinx. Raven tries to be a hero in spite of being the daughter of an Eldritch Abomination (and being one herself when she gets angry enough), while Jinx became a villain solely because she figured her 'bad luck' powers couldn't be used for good.
Azula and Zuko both lived under the same abusive father and the same expectations, and Zuko spends a lot of time trying to be Azula, but never comes close to her levels of cunning and cruelty and (eventually) turns to the side of good.
Hama is a fellow Waterbender who develops a deadly Waterbending technique in order to escape from a Fire Nation prison. However, her Irrational Hatred of the entirety of the Fire Nation lead her to utilize the aforementioned technique to terrorize and harm innocent Fire Nation citizens. She also ends up teaching Katara the same technique. Katara very nearly became consumed with the same vengeance when faced with her mother's killer but decides it wasn't worth it after a little help from Aang.
In the episode "Ramlak Rising", the Anti-Hero Captain Tunar to protagonist Lion-O. Like Lion-O, he too lost his home to a horrible monster, one that he wishes to destroy at all costs. Seeing where that mindset eventually leads convinces Lion-O to move past it.
Rataro, a leader who treats his own people with cruelty, as opposed to how Lion-O is trying to save his people from slavery in the same episodes as well as treating one of Rataro's minions with mercy. As Lion-O put it, Rataro's people are slaves on the other side of the whip.
In that same vein, Mumm-Ra also fits; he leads the lizards against the cats by exploiting the generations of racial tensions and hatred building for so long. Lion-O, on the other hand, gets people to fight on his side by showing them kindness.
Finally, we have Vultaire, who believed that the birds of Avista would be perfectly safe by staying out of the war below, when Lion-O knows the only way to win the war is to unite. Although Vultaire does learn to unite...when he joins Mumm-Ra.
American Dad! parodies this trope with the Anti Christ who intentionally strives to take aspects of Jesus and the Bible and turn them inside out. For instance, he manages to trap Stan, Jesus, and Francine in a Death Trap that fills with sand... which breaks after two seconds. He gives an Evil Laugh and declares that since Jesus is a carpenter, he can't build to save his life.
American Dragon Jake Long: Huntsgirl and Jake are both forced by their roles to be enemies. Jake being the protector of magical creatures, against Huntsgirl who has to hunt them. Jake has to deal with accepting responsibilities while Huntsgirl has to fight her fate.
The Flim-Flam Brothers and the Apple family both run family-owned, apple-based businesses and are equally passionate about providing a quality product loved by all, but the former favor machinery, trickery, and winner-takes-all competition over the hard work, honesty, and cooperation of the latter.
The clone Pinkies from "Too Many Pinkie Pies" embody Pinkie Pie's primary personality trait (wanting to have fun), but completely lack any of the traits that make her a complete person (reliability, integrity, insight, friendship, etc). They are essentially Pinkie Pie distilled to her most prominent, visible, and annoying persona.
In Equestria Girls, the film's Big Bad Sunset Shimmer is Twilight as the new alicorn's Evil Counterpart/Foil. They're both intelligent and students of Celestia, but while Twilight, though somewhat antisocial before meeting her friends, was modest and polite, Sunset Shimmer was condescending, rude and arrogant. Twilight never sought the power of a princess, yet proved deserving of it anyway, while Sunset Shimmer craved power and proved herself unworthy of being a princess. Even their names reflect this ("Twilight" and "Sunset", "Sparkle" and "Shimmer"), and to top it off, she's voiced by Rebecca Shoichet, who does Twilight's singing.
Regular Show has Mordecai and Benson. While Moredecai is easy going and tends slack off as much as Rigby, he does try to follow the rules, and is diligent enough to finish his work, and Rigby points out he sometimes acts like Benson. While Benson is hard working with a real short temper, he doesn't seem to have any friends outside the park and tends to be alone most of the time.
The Fairly OddParents has Cosmo and Wanda's Anti-Fairy counterparts. Anti-Cosmo is smart, cultured and evil. Anti-Wanda is a dumb hick who eats with her feet.
Daria has the title character and Jodie Landon. They're both quite intelligent, and similarly cynical about their surroundings and peers. However, Jodie is much more active, and still wants to change things even if it costs her values while Daria is mostly content to observe and snark. It is implied that as a Token Minority Jodie can not afford to be as apathetic as Daria, because everyone (including herself) expects her to represent the black community in a positive light. Also, parental pressure, something Daria is better at dealing with.
The rare heroic version in Harvey Bullock. He very much does what Batman does as he bends (read: breaks) the law quite regularly to get results. Also, much like Batman and his seemingly harmless alter-ego Bruce Wayne, Bullock seems inept as all hell but is as capable of a fighter as Batman when surrounded by bad guys or Mooks.
In the British Political System, the leadership of the most prominent opposition party consists of a group of spokesmen and -women with particular portfolios (the Treasury, Home Affairs etc), as counterparts to the Governmental Cabinet — the intent is that if and when the current government falls (as in lost the confidence of Parliament), the hitherto-opposition can take up the responsibilities of governing in short order. This is known as The Shadow Cabinet. It's far less awesome than it sounds.
The appropriately named "shadow types" in Myers-Briggs/Kiersley/etc. personality theory, which is based on Jung's original work. They can be messy, and there's a book on them called "Was That Really Me?"