Genericist Government

In non-political settings, or anything not based on a real-world government, the local government and how it got its power or where it derives its power tends to be really vague. Sometimes there's a princess or two hanging around since, you know. But generally speaking, all we have to go by is that good rulers are good rulers and bad rulers are bad rulers, without any sort of explanation about how exactly things are run. For tax policy, as an example, at best you might get "good rulers don't tax and evil ones do", without really explaining how anyone funds anything without taxes.

This concept is the Genericist Government. Genericists are government the way people who aren't involved in government see it—definitely present, but not relevant except in its lowest level of bureaucracy (e.g. the local police and the DMV). They're most common in works of fiction where the main point of the story is the Call to Adventure, so the nature of government and political science isn't all that important to the plot. This trope is a common cause of much Fridge Logic.

Not so common in non-fantasy works since those are usually based on real-world governments, instead of whatever we think monarchies used to be like. No Party Given is a related trope when a fictional government is based on the specific government of a specific country, but the specificity stops at the individual politicians' ideological affiliations.

Related to Skeleton Government, though a Genericist Government can be of any size. May involve an Evil Chancellor. Subdivides into The Kingdom, The Empire and The Federation.

Anime and Manga

 * Chrono Crusade: In the manga version, we know there's a Queen of the Demons and there are "Elders" that have some position of authority, as well as possibly a caste system or military (Chrono is specifically mentioned to be a soldier, and some demons are referred to as "low-ranked")...but we're never really clearly told how all of this works, and who makes what decisions. We're only really told that it's "corrupt." The anime is even worse in this regard, the demons are said to have a leader that rallied against God, but are still apparently working under God...

Film

 * Monty Python and the Holy Grail: Rather deliberately subverted, where King Arthur claims to be a king, and the peasant blithely demands to know what kind of government he offers, and how it is an improvement over the anarcho-syndicalist model already practiced by the local peasantry (which he insists on describing in detail). The conversation ends with the peasant complaining about "being oppressed" when King Arthur attempts to shut him up in annoyance.
 * Star Wars and its prequels use this trope. Star Wars blurs the line between democracy and hereditary autocracy. Naboo is a monarchy with an elected queen who serves a fixed term, and Alderaan is a hereditary principality whose head of state, Prince Bail Prestor Organa, Viceroy and First Chairman, is also the planet's representative in the Galactic Senate (and later, the founder of the Rebellion). Darths and Droids makes fun of this. Naboo's constitution isn't as silly as it looks. Malaysia's mostly ceremonial King serves a fixed term of five years and is chosen from the royal families of the several states of that country. Naboo might work the same way. (Except that in Malaysia, a minor would be passed over and would have to wait until it was his family's next turn to be king.)
 * Senator Organa represented more than just his planet, but the entire Alderaan sector, which included the other inhabited planets near it. This is how Senatorial representation worked. Presumably the other planetary governments respected him enough to have the Alderaanian head of state as their representative in the Senate.

Literature

 * Inheritance Cycle: It's not terribly clear why the King of the Empire is such a bad guy, nor is it explained what was so great about the previous government, which seemed to just be a bunch of guys with huge dragons running around doing... something. Partially justified by Unreliable Expositor.
 * In Harry Potter, the title of Minister for Magic doesn't appear to be an elected position. The Daily Prophet is said to be explicitly in the ministry's pocket. The only other newspaper mentioned is the Quibbler, which seems to be for conspiracy buffs, which seems to indicate that whatever the government is, its views are unchallenged by any kind of opposition. Which is pretty bad, all things considered.

There's almost no resistance when the feared villains openly take over, except from those already in conflict with them. A major plot point in the last book revolves around no-one but the heroes realizing that pretty much every wizard has enough power to easily punch through their enforcers and just walk out.
 * Discworld: Somewhat justified: The government of the Lancre kingdom literally consists of the King, the Queen, maybe a few other servants, and a standing army [Shawn Ogg, except when he's lying down], who also does some servant duties as well. In this case, though, Lancre only has a population of 500.

Most of the governments are pretty generic, except for Ankh-Morpork (Best. Tyranny. Ever.), Klatch and Sto Lat(monarchy) and, kind of, Pseudopolis - in Unseen Academicals, Lord Vetinari is very amused by the fact that they decide to try a brave new experiment in democracy, and promptly vote not to have to pay taxes.
 * The Castle in Septimus Heap has a Queen and a Palace buraucracy, but it is never shown what her job exactly is or what the bureaucracy does, apart from the vague "keeping the Castle safe".

Live Action TV

 * Star Trek: Does the Federation have an assembly? How are its members selected? What's the role of the President (seen in Star Trek Deep Space Nine)? Is Starfleet Earth's space military, the Federation's as a whole, or is it some combination? Is it even a military force at all? We don't know how the civilian government is selected at all, the role of Starfleet (how does it answer to the civilian authority?), what it means to be a member of the Federation (does a member planet completely lose its independence, or is it like being in the UN?)...
 * Star Trek: Articles of the Federation laid out some of the fine points; the Federation, appropriately, seems to be a federal legislature, not entirely unlike the American Congressional system (or perhaps the Articles of Confederation; member nations retain a lot of individual control).

Tabletop Games

 * Dungeons and Dragons lists a magocracy, a government made up of magic users as a government type. It was also used in a vague manner in The Movie and the sequel. Given the vast distinctions between inherited magic (sorcerers), book-learnin' (wizards), and divinely-granted magic (clerics, etc.), "magocracy" raises lots of questions...

Magocracies tend to be run by wizards, the ones who benefit the most from a structural edifice with libraries and suchlike. They tend to be like a university on a larger scale, with everyone who can't cast being stuck as a servant. Pretty much a plutocracy/meritocracy, except the only merit being measured is how good you are at playing hob with the fabric of reality and nuking those who annoy you. Except for the monarchy/magocracy, where the ruling family are all sorcerers.
 * GURPS lists "Utopia" as a government type.

Video Games

 * The government in Mirror's Edge is vague. The Zero Punctuation review offers up the idea that the player character is not La Résistance but a straight-up terrorist.
 * Most Final Fantasy games seem to be right up this trope.
 * Mass Effect: We know the three (later four) people at the very top of Citadel space, law enforcement on the Citadel, a small organization of black-ops agents with extremely high authority, and beyond that... not much else. We don't see any middle management or local self-government except on two Vice City planets that aren't even part of Citadel space. We know that Earth is still fractured into nation-states, but nothing about the colonies.
 * To be fair, much of that information is present in the codex (though in the secondary part). For example, you find out that the Asari are made up of a group of nation-states reminiscent of Ancient Greece, and the only official that the Asari recognize among their own people is the Asari Councilor.

Web Comics

 * Used in Dominic Deegan, where the government is vaguely defined. We know there's a king, and up until recently there was an order of Royal Knights, and that Dominic doesn't think much of the government as a whole (likening them to criminals) and...well, that's about it.