Some people are good at fighting. Some are good at thinking. Some have special powers. And some... have just the right info to make everyone else useful.
This is the person who always seems to have the dirt on everybody. The person who runs an information-gathering system, with a network of informers.
The Knowledge Broker has a web of contacts stretching into various organizations, industries, and government agencies, and always seems to know what's going on. Sometimes the Knowledge Broker seem nearly omniscient. He/she always seems to have just the right tidbit of information for whoever is willing to pay their price. For the most part, he remains impartial despite his vast influence, and most people know to stay on his good (or at least indifferent) side.
This is a person who is not mysterious (Compare Mysterious Informant). Everybody knows that when you want information you go talk to this person. Usually of dubious morality. Often your innocent hero has a buddy who grew up on the wrong side of the tracks, and knows that they ought to start by talking to "Big Eddie" or whoever, cause he always "knows anything that goes down."
Sometimes the source of information is more upscale in appearance, in which case they are probably also The Humphrey. They usually want something from the hero before they hand out the information (unless they owe the Hero a favor, or have a crush on him). Often they'll want nothing more than cash, but sometimes they want the Hero to run an errand for them. Or they may trade information for information. If there is romantic subtext, she might ask the Hero to be her escort somewhere — always a good choice for drama when the hero is looking for information about the kidnapping of his love interest. Obviously saving his true love justifies cheating on his true love — or does it?
Many times this character is relegated to a position as a Plot Device. When the Knowledge Broker is given Character Development, expect him to have a traumatizing past and/or an old relationship with one of the protagonists. When acting as a contact for the heroes, expect the Knowledge Broker to supply the catalyst to propel the story forward. If the heroes get stuck, expect him to suddenly come up with a new lead. If he's mostly in it for the money, expect either a Face Heel Turn or a Heel Face Revolving Door that may one day make someone put a gun to his head. If he's less-than-impartial towards the main character, expect him to deny payment, with an excuse like "I owed you a favor anyway." Likely to Default To Good (if only because the good side winning would keep them in business); rarely, if ever, is this character working strictly for the antagonist.
If the contact is a recurring character and the Knowledge Broker and the protagonist are different genders (or not), expectromanticsubtext.
Real Life information brokers tend to be consultants who work in market research, though there are exceptions.
See also The Fixer.
Fuuchoin Kazuki from Get Backers theoretically does this for a living, although he's more often seen kicking ass.
Haruo Nijima from Kenichi: The Mightiest Disciple is a partial case of this. Though he has incredibly skills in analyzing enemies and information gathering in general, he acquires all his intelligence for the sole purpose of furthering his own goals of power.
A similar role (information broker to the villains) was played by the Monitor during the run-up to Crisis On Infinite Earths. His role in the actual Crisis is quite different.
In some instances, Jason Todd as the RedHood has played this role, bringing valuable information to heroes. And, occasionally, villains. For his own ends, or to ensure they end up getting themselves killed. If it came up more often he'd be a Magnificent Bastard.
Batman villain The Penguin functions as an information broker for Gotham's underworld, with a little arms dealing thrown in for good measure.
Information is just another commodity in the world of Finder, and Lynne Grosvenor is implied to be one of the best infotraders in Anvard. Within an hour of his sisters' mugging, he's recovered their belongings and tipped off the police (if not something worse, considering how protective he is of Marcie).
Nomad, from Marvel Comics, confronts the 'Favor Broker', who is also a Big Bad, multiple times through his title series. The Broker claims not to like the position he is stuck in but is too piled up with favors to ever quit.
In the Astro City story, "The Tarnished Angel," Donnelly Furguson uses his knowledge of the city's underworld to find jobs for the B-rate villains of Kiefer Square. He arranges for all of them to be hired for a city-wide crime spree planned by fallen hero El Hombre, who plans to kill all the villains and restore his heroic stature. Steeljack didn't like associating with him even before all this came to light, but because Furguson didn't have a record he was one of the very few people he knew with whom he could freely mingle without violating his parole. He never gets what's coming to him, but he's not the same man after the El Conquistador incident, either.
The Harlot functions as this in Fall Of Cthulhu. As one of the most powerful entities in the Dream Land, she can provide virtually any form of information; her asking price is generally a piece of the client's body, though she will occasionally accept pieces of the client's mind — especially in the case of Raymond Dirk.
Angel had a creature, Polyphemus, with an encyclopedic knowledge of demonology. There was some romantic subtext between him and Laura, a former watcher.
The 3 Shingouz in Valerian.
Feetus from Grimjack. Notable in that he and Grimjack were old war buddies and genuine friends. He plays a more important role in the plot than just a source of information for Grimjack.
Dungeon Keeper Ami features Keeper Midori, who fits this Trope to a T. She keeps close tabs on all the warring factions in the story, often popping up at opportune moments- such as lulls in the fighting -to offer information on their enemies, at a price.
Futari Wa Pretty Cure Blue Moon has Omemi Emiru, a different sort of an Alpha Bitch who uses this (something she calls a "talent" for coming upon other people's information) to keep her classmates in line. Her Etherium powers reflect this, as she uses her illusion abilities to, in a sense, construct what others see of reality, made more convincing by what she's found out about them.
The Merovingian from The Matrix sequels. "I am a trafficker of information, I know everything I can."
Neo also qualifies, before his Red Pill, Blue Pill decision in the first minutes of the original film.
In Osmosis Jones, this was the function of the Flu shot. Kinda justified, if by a long shot, by those who know a bit of biology.
In Heat (1995) Robert DeNiro's character consults such a figure for intelligence on potential heists and police opponents. When DeNiro asks him where he gets this stuff he replies that it just comes to him through the air (his house is festooned with antennae and located on a hill above Los Angeles).
Louis, the French guy from Munich, along with the rest of his family.
Skinny Pete from the 2003 remake of The Italian Job acts as this for Charlie and his crew when they pull their final heist in L. A.
Doctor Know... is in the know. And is also an unreliable search engine that charges per-question, but that's besides the point.
Billy from the Final Friends series by Christopher Pike always knew where everyone was all the time. No one questions how he knows.
Varys "The Spider" from A Song of Ice and Fire. Having no title or wealth (being referred to as Lord out of courtesy basically), and being a foreign eunuch, he only managed to survive the overthrow of the Targaryen dynasty because of his usefulness.
Chrysalis, the transparent-skinned owner of the Crystal Palace bar in the Wild Cards universe, uses a telepathic bartender and tiny spy-creatures spawned by a unique Joker to gather information— along with the traditional bribes and espionage.
The sheer scale of the Star Wars universe dictates a rather absurd number of these. By far the best, though, is smuggler-in-chief Talon Karrde, whose organization, which took over after Jabba The Hutt's enterprises collapsed with his death, was basically built on information brokering. He ended up defaulting to the New Republic's sideafter Thrawn had him kidnapped to try and coax the location of a lost fleet out of him. In the Hand Of Thrawn duology, he took a certain crucial bit of intelligence to Supreme Commander Pellaeon in time for a Big Damn Heroes moment, and his organization sets up between the newly at peace New Republic and Imperial Remnant, making sure information flows freely to both sides so there won't be any nasty secrets. His old mentor basically knows everything, but withdrew from galactic affairs.
Around second place or so are the various other important smugglers, and government agents are somewhere around twentieth. Unless they're Thrawn's agents, that is, or wherever and whatever he gets his intel from.
Pahvulti, the renegade TechPriest in Simon Spurrier's Warhammer 40000Night Lords novel Lord of the Night. He was exceptionally good at his job, becoming the information baron of an entire hive, due to his mentality of a cad combined with his thought processes being that of a computer.
Charles Augustus Milverton of the Sherlock Holmes tale that bears his name.
After refusing to back down from a touchy case and losing her position, Wolfe from the Andrew Vachss Burke books takes on this role, and is apparently the best at it.
"Done it" Duncan of the Discworld acts unwillingly as this, as he claims to have performed every crime that happens in the city, including a Suspiciously Specific Denial that can be very useful to the Watch.
Also, Fred Colon from Night Watch forward, in a strange way. After being pulled off the streets, he is given an office, where he always keeps a kettle going and a box of free doughnuts. This is a favourite hang-out for ex-cops, old cons and petty criminals, all of whom have an ear to the street and gossip like old washerwomen. Colon hands over the information gathered to Vimes, who gladly pays for the tea and doughnuts in return.
The former CIA from Snow Crash is a knowledge-brokering company. Among other things it employs camera-laden guys who roam around recording everything, in case it'll come in handy later.
Gyoko from Shogun seems to know everything, and has a network of courtesans who supply her with information. In a society that values titles and military power, she manages to do much with the use of information only.
"Papa" Friedlander Bey from the MarÓd Audran series deals exclusively in information on a global scale; governments operate, or not, based on the information bought, sold, and traded by him.
Magician Humphrey from the Xanth series is not ranked as a magician for being born with powerful magic, but rather for his ability to find information. He can answer any question, but because so many people have questions, they have to get past three obstacles to get to him and work for him for a year.
Live Action TV
Hatter from the miniseries Alice. Ratty describes him to Alice as "a man who knows," and he seems to be connected with just about everybody - the Hearts and the Resistance. His street smarts and knowledge of Wonderland are a help, and even when he and Alice have basically run out of plans and resources, he lists an obscure woman he knows through about eight different people and suggests talking to her, although he admits it's rather a long shot.
Limehouse from Justified has an extensive network of informants throughout Harlan County and the neighboring areas. If you are a client of his unofficial bank, he will share the information if you ask nicely. He is a leader of a black community in the mountains of Kentucky and his community survived since the Civil War by always knowing what its enemies and allies were up to and where the next threat was coming from.
JK from Kamen Rider Fourze has information on just about every student in the school and it's his first-year in Amanogawa High.
Star Trek: Deep Space Nine: Garak, Odo and Quark all play this role. Garak's comes from the intelligence world and he has connections everywhere and in every facet of society. Odo's tend to be police, security and politically based and Quark's tend to be economic and black market.
Trick from Lost Girl. Part of it comes from being the owner of a bar that's one of the few places open to both Light and Dark Fae, part of it from having once been the Blood King.
Dorium Maldovar, owner of the Maldovarium, who knows - among MANY other things - what is The Question in Doctor Who.
Having good contacts is key to survival in Shadowrun. If you don't wanna die or get arrested by Lone Star, that is. They're even ranked: Level 1 contacts are basically acquaintances, Level 2 are slightly more trustworthy because they know you and have worked with you in the past, and Level 3 is an old friend who will bend over backwards to help you.
The rankings are changed in Fourth Edition - now there are two categories, Loyalty and Connections. Level 1 Loyalty is someone who likes you but doesn't really care about you; Level 6 is someone who will dive under a bus for you. Level 1 Connections... aren't (a Mafia grunt who hasn't "made his bones"); Level 6 Connections are the people you need people who know people to see (the Don).
The entire Nosferatu clan serve this function in Vampire The Masquerade and its PC counterpart. Being vampires that live Beneath the Earth and have the ability to turn invisible, they have considerable influence- allowing them to charge high prices for information and make life unbearable for unwanted customers.
In Vampire The Requiem, this role belongs to the Mekhet clan, who have the added advantage of looking normal, and being able to acquire information directly through supernatural means (such as mind-reading, psychometry, or astral projection).
Also, every mage, to a certain extent, though the Mysterium are the ones with the main focus on it. One Sourcebook provides detailed information on how their "knowledge economy" works.
In Werewolf The Apocalypse, the Corax wereravens (and to a lesser extent, the Bone Gnawer Garou) serve as this to other supernatural beings.
Mass Effect has the Shadow Broker, the completely unknown head of a vast Information Brokering Empire. Even the highest ranking members of the organization communicate with their boss only through audio-only communications channels, in which the Shadow Broker uses a computer generated voice.
The Illusive Man at the head of Cerberus is also in the same business, but he doesn't use it for profit but to always be ahead of his enemies and to use the information he has as bribes or for blackmail. He doesn't sell information, but only shares it to make other people depending on him.
In the second game, Liara starts her own business on Illium, but for her the profits are mostly to fund her own investigations into the identity and location of the Shadow Broker, who tried to find the dead body of Shepard and sell it to the Collectors and kidnapped her partner when she gave the body to Cerberus first. Her real goal is to kill the Shadow Broker and rescue Feron. Not bad for the socially awkward archeologist from the first game.
The Lair of the Shadow Broker DLC takes Liara and Shepard to the secret base of the same. Where it turns out that the current person behind the desk is a huge gorilla-like alien who was kept as a slave and pet by the last Shadow Broker. After he killed his master in his own private chambers, he simply sat down at his computer and continued business as usual. And after he is killed in battle and the computers restart, Liara does the very same thing, instantly becoming one of the 10 or so most powerful people in the entire galaxy.
Due to the way Archadian high society works, pretty much everyone in Archades is a Knowledge Broker to one degree or another.
The Oracle in Deus Ex is an AI born in cyberspace from the sheer information in it, who trades what he knows for information he does not have (this doesn't have to be of any value, a "joke you heard recently" and your breakfast are both things he requests in exchange for information). However the Oracle only appears at three points in the game, all in emails that are entirely optional to read, and everything we know about him is Word Of God.
Pretty much everyone you talk to in City of Heroes. Seriously, how does Joe Shmoe know which warehouse the Trolls are selling firearms out of? Granted, many of your contacts have some relation to law enforcement or the criminal underworld, but it gets quite silly after a while.
Kage the Florist (or just The Florist) in the Ryu Ga Gotoku games.
Wiseman from the Dot Hack R 1 Games had this as his initial occupation, before joining the team for real.
In I Will: The Story of London for the Pioneer Laseractive, the man to see was Mr. Pound AKA "Antenna", who runs a Britain-wide information network. He's easily recognised as he's the only person in the entire game who carries two umbrellas in one hand.
In Privateer Roman Lynch provides information to the protagonist to aid his quest in finding out about the mysterious artifact he's acquired, at the expense of performing missions for him.
Redd White from Phoenix Wright: Ace Attorney. His company, Bluecorp, was basically an information-gathering corporation that specialized in obtaining blackmail material concerning big-name individuals such as celebrities, politicians as well as high-ranked people on the judicial system, effectively making White a man above the law.
Shadow of Super Stories makes her living this way. Whether she has a supernatural ability for getting information or is just very good at her job has not been answered.
Jonathan Patches of The Gungan Council can get information on anything as well as make sure no one gets certain information one doesn't want to let out.
Geezy the Pegelount is one of these in the Wretched Hive of Tortuna in Galaxy Rangers. A later episode reveals that his cousin is one of Her Majesty's victims (explaining why he's no fan of hers). Fanon also suspects Doc was one of these before being "reluctantly" recruited into the Rangers.
Mr. Cairo from Phantom 2040. He only values knowledge and no amount of currency, which is probably why he hasn't told the Big Bad who The Phantom is despite the hefty reward.