Dmitri (Id) - the elder brother is a womanizer, a drunkard and a hedonist.
Alyosha (Ego) - the younger brother is a sweet, meek boy who wanted to become a monk and is the only member of the family who manages to keep a good relationship with the others.
Ivan (Superego) - a cold, brilliant intellectual and atheist with much contempt for the rest of mankind.
Grubbs (Id): Impulsive, often doesn't think before acting.
Kernal (Superego): Wanted to give up fighting the Demonata and withdraw to keep at least some beings alive. Oh, and he had his * eyes* dug out by Grubbs.
Bec (ego): Mediates between the other two members of the Kah-Gash. Especially at the end, where she negotiates with Lord Loss and brings about the end of both universes.
Granny Weatherwax (Superego; although she's described as having a big ego, she's definitely the most rational and chilly of the three.)
Nanny Ogg (Id)
Magrat Garlick (Ego, her role being specifically described as "running around getting the other two to make up after they'd had a row". A rare example of the ego definitely not being the leader.)
Harry Dresden: Somewhat rebelious, but never for the sake of rebeliousness alone (ego).
Thomas Raith: Hedonistic, pleasure-seeking. Hell, he feeds off of emotions just to live (id).
The times Harry's three-man team switches around, the other characters usually fill one of these slots (Michael Carpenter: superego, Kincaid: id, etc. If Sanya is brought into the mix, Harry is oftentimes shoved to the id, and Sanya becomes the ego.)
Gard—concerned with battle and survival: Id
Hendricks—philosopher, moralist: Superego
Marcone: Ego
Ender's Game and its sequels have a power trio of the three major sentient species:
Buggers: Highly organized, virtually no concept of the individual, communicate psychically faster than the speed of light, very technologically advanced, put the survival of their species first but don't seek to destroy other species. (Superego)
Humans: Very high-tech, artistic, individualistic, but also prone to irrational decisions and chaos. Have a bad habit of nearly destroying other sentient species. Good overall, but can still be pretty dastardly. (Id)
Pequeninos: Very low-tech compared to other species, tied to their traditions, have a much greater concept of the individual than buggers but still less than humans, generally open-minded. Tribes fight with each other, but outside of these battles, they try to avoid conflict. (Ego)
One can group the three Wiggin children in the same way:
Peter Wiggin: Borderline(?) psychopath, extremely ambitious, driven (id).
Their victim (i.e. the poor yutz barbarian they've roped into being the person who will bring civilization to his homeworld) gets to be "Ego" as he has to put together Raj's wise experience with war and humanity with Center's cold logic and near-infinite knowledge.
Hermione: Intelligent, respectful to authority, has proper 'manners'. Her 'know it all' quality can get on the other characters nerves. (Superego)
Harry: He has "a saving people thing" as Hermione says in Harry Potter and the Goblet of Fire (Id)
Ron: Act as the 'middle' of the two when Harry wants to rush off to save somebody but Hermione wants them to take their time being as cautious as possible. (Ego)
The three could also be seen as the embodiment of Body (Ron), Mind (Hermione), and Heart (Harry).
It's also easy to see Harry as the Ego, since Ron seems to fit the traditional description of Id.
Given the frequency with which Hermonie and Ron get into fights and Harry is caught between them, it seems more like Harry is Ego, Ron is Id and Hermione is Superego.
Professor Mc Gonagall: Why is it, when something happens, it is always you three?
Also Lampshaded when the narrative refers to that "little voice" in Harry's head telling him what to do. It sounds just like Hermione...
A Secondary trio is presented in Deathly Hallows during the main trio's absense from Hogwarts. Though they do not fit the bill as easily as the main three, they are:
Neville: completely devoted to Dumbledore's Army and the La Résistance taking place at Hogwarts. (ego)
Ginny: Brave and loyal, but a bit of a hot-head and impulsive. (id)
Luna: Very smart and an idealist. (superego)
The Marauders also fit this fairly well:
Lupin: calm, studious, the most prone to common sense out of the three (superego)
James: over-confident and mischievous, but less reckless than Sirius (ego)
Sirius: the rebel of the group, doles out the harshest bullying to Snape and is driven to intense emotion (id)
Some would argue that James is the "id" and Sirius is the "ego".
Alice: Witch-to-be teetering on the edge between good and evil. Is always willing to use the dark to accomplish her aims but does not wish to belong to it. (Id)
Tom: The Spook's apprentice, always torn between his duty to his master and his friendship with Alice. He always wants to do what is right, but often isn't sure what that is. (Ego)
The Spook. Former priest who has decades protecting the County from ghosts, witches and other monsters. He is always sure of what the right thing to do is, and tries not to let mercy or human emotion get in the way (Superego).
Alaska Young: Intelligent, but brash, impulsive, and arrogant; does what she feels like doing and doesn't care how it impacts anyone else until later. (Id)
Miles "Pudge" Halter: Calm, kind, withdrawn, intelligent, and usually the most reasonable person of the three. (Superego)
Chip "The Colonel" Martin: Short-tempered, but incredibly intelligent, meticulous, and well-spoken. (Ego)
The Sword of Shannara: Shea and the two criminals who captured him form one after they agree to team up.
Shea Ohmsford: Nice Guy and the only one to have all the information about what is going on; the only one who can complete the mission and defeat the Big Bad (Ego)
Panamon Creel: Flamboyant highwayman and professional criminal who makes friends at the drop of a hat, believes in living life to the fullets, and has a Hair-Trigger Temper that can be set off without warning (Id)
Keltset: Calm, rational, messianic figure who doesn't let his emotions get the best of him. Mute. (Superego)
The Reaper: A being forged of pure insticnt, created to be the ultimate predator. Killing is as insinctual to it as breathing; when it wants something it just keeps on coming until you or it is dead. (Id)
The Changeling: Cautious and manipulative, using its Shapeshifting abilities to confuse and mislead; waits for the perfect opportunity to strike despite being more or less driven by spite. (Superego)
TheDagdaMor: Repressed Chaotic Evil, he prefers to work through subordinates but isn't afraid to confront his opponents directly when the opportunity presents itself. A planner with the ability to be flexible. (Ego)
Robert Baratheon is devoted only to the physical pleasures of life; food, drink, sex and glorious battle! (Id)
Stannis Baratheon is cold, rational and entirely devoted to upholding justice and the laws of the realm as they are. He often feels dishonoured by his brother Robert's impulsive actions in court, or his impulsive actions in general, such as having a casual sexual encounter on Stannis' wedding night, in Stannis' marital bed. (Superego)
Renly Baratheon is more level-headed and down to earth, neither overly impulsive like Robert nor extremely strict like Stannis. However, he subverts part of the trope in that he offers no mediation between Robert and Stannis. In fact, he adds to it somewhat as Stannis percieves Robert as favouring Renly over him. (Ego)
Played straight in the meeting in A Clash of Kings between Renly, Stannis and Catelyn Stark:
Stannis demands that Renly submit to Stannis and accept Stannis as king due to Stannis, by law, having the superior claim by being the elder brother. (Superego)
Renly demands that Stannis accept him as king, due to him seeing himself as fulfilling a more romantic ideal of king, basically. (Id)
Catelyn Stark desperately tries to mediate between them and get them to come to a compromise and join together against their extremely powerful common enemy, the Lannisters. (Ego)
On a mission to a world that at first seems to have the hat of pilot-worship, four of the New Republic's best pilots try to sort things out. This is possibly the funniest book in all of Star Wars.
Id: Wes Janson, dubbed "the Darling One" by Adumarians. Loves making jokes, snarky observations, believed to have very little maturity. (Really he is mature when it counts, but he mouths off a lot.)
Superego: Derek 'Hobbie' Klivian, "the Dour One". He's the group's cynic, though far from The Eeyore.
Ego: Both Tycho Celchu, "the Doleful One" and Wedge Antilles, "the Dilligent One". They're both more inclined to leadership and somewhat more serious. Somewhat. Tych is given to occasional, devastating one-liners, and while Wedge is usually there to be appalled at jokes, after he gets laid and later gets back into his starfighter he briefly surpasses Wes.
Wedge: "We have the right tools to subvert our Imperial admiral."
Hobbie: "What tools?"
Wedge: "Oh, Wes's maturity, your optimism, and my diplomatic skills."
Id: Flim, the con artist physically impersonating Thrawn; his ambition is mostly to survive and get paid. His grasp of strategy and tactics is negligible, and to keep up the deception he needs
Superego: Major Tierce, strategist, feeding Flim tactics.[[supersecretspoiler: A clone with a bit of Thrawn burning in his head]]
Ego: Moff Disra, who set the triumvirate up in the first place, provider of supplies, handler of political fallout. Doesn't really get along with Tierce, but they need each other and are undeniably effective.
Id: Ned Land (impulsive, violent, mostly concerned with food, hunting and escape)
Superego: Conseil (imperturbably calm and reasonable, cares about nothing except his master's welfare and cataloguing wildlife)
Ego: Professor Aronnax (mostly calm and scientific but also gets upset about being held prisoner; mediates between his comrades)
The book is, anyway, one massive psychoanalysis: being captured and dragged down to the depths in a mysterious vessel, to encounter frightening alien-looking creatures and to descend into a maelstrom., etc. etc. etc. ...
The Wonderful Wizard of Oz presents a neat inversion: the trio accompanying Dorothy are defined by what they lack. Double-subversion in that their perceived lack is actually their defining trait.
Scarecrow (No brain - the anti-Spock), and really The Smart Guy
Tin Man (No heart - the anti-McCoy) and really The Heart
How perceptive! The idea of "lack" is central to the writings of Jacques Lacan, who developed Freud's ideas. So this must be the classic "Lacanian Power Trio".
Willem Vanderling (Id): Adapts to the endless brutality on Sangre quite easily, becoming a murderer and cannibal in a matter of weeks.
Bart Fraden (Ego): Is willing to commit stupefyingly horrid war crimes for the sake of overthrowing the planet's corrupt elite (It Makes Sense in Context).
Sophia O'Hara (Superego): Has the most conscience of any character in the novel (though that isn't saying much). Frequently questions Fraden's "leadership" and attempts to instruct him morally, despite ultimately being ineffectual.