"The UN is the accepted forum for the expression of international hatred."
—Sir Humphrey, Yes Prime Minister
Those dudes in New York City who try to solve the world's problems. They were set up to prevent World War III, heck, it's worked so far! At the very least, the UN has been more successful than their predecessor, the League of Nations, who were created to prevent World War II - and we all know how successful they were at that.
Actually, they're ambassadors from all the UN member states, plus the many, many interpreters.
Since every nation can join (and almost all have, although Switzerland didn't join until 2002!) that means every nation can stand up in front of the world and air their grievances.
The UN is funded based on the idea that the richer you are, the more you pay.
The UN consists of many parts. The General Assembly and the Security Council are the most well known. The General Assembly is much like the U.S. Congress, specifically the Senate—every nation gets one vote (unless you were the Soviet Union, then you got three  due to the agreements made when joining the U.N., and yes, they always voted the same way.). The Security Council is where the real power is. Since 1966, the Security Council has had 15 members—five permanent members and ten rotating countries elected for two-year terms by the General Assembly. Only the Security Council can take military action. Much of the "weakness" of the UN is due to the fact that any permanent member (US, UK, Russia, China, France) can veto any Security Council resolution simply by voting against it. The theory was that because Security Council resolutions are (theoretically) binding, it would not be reasonable for one of the Big Five to be forced, by law, to act against its interests. Permanent members which wish to express displeasure with a resolution but don't see much use in pissing everyone off by vetoing it tend to abstain; that way, they don't vote for the resolution, but they also didn't vote against it (which would be a veto).
Thus you can see some of the problems. During the Cold War, the Soviet Union (and later China, when the vote was switched from the Republic of China to the People's Republic of China) would use the veto against the Western nations. Today, it is the United States which most often uses the veto, typically striking down resolutions it sees to be taking the Arab/Palestinian side in the Arab-Israeli Conflict. These vetoes frequently come in the face of otherwise-unanimous votes in the Council, which annoys a lot of Arab countries.
The veto power sometimes gets wielded by China (and less regularly, Russia) to strike down resolutions regarding human rights, even if it doesn't affect human rights in that country. Coupled with a Human Rights Council which is so farcical that Libya was on it at the same time the General Assembly and Security Council enforced a no-fly zone on the country.
Often overlooked is the many successes of the UN; The World Health Organization, Food and Agriculture Organization, International Civil Aviation Organization, UNICEF, and many more. Bickering and corruption is there, but so is cooperation and, at least, a place nations can try to settle things without shooting each other. Between the UN and nuclear weapons, the second half of the 20th century and the 21st century have been remarkably low on bloodletting.
There are, however, some downsides to the UN that makes its existence questionable: As alluded to above, corruption and bickering do exist. More importantly, there were also extremely questionable practices, such as the UN condoning and prolonging Darfur's genocide policy, even dismissing questions from its own investigative team; not investigating a peacekeeping force employed by the U.N. after it fired into a bunch of unarmed protestors that killed and injured dozens; how it cannot agree on a definition on terrorism even 7 years after 9/11, and how not only one of its programs, "Oil for Food," proved to be a big scam, but they failed to investigate or punish the people responsible. There is actually a reason why some people gave it the derisive nickname of "the clubhouse of dictators, thugs, and tyrants."
Not to be confused with the punk band of the same name.
Juvenile Diplomats- Model UN
Since the creation of the United Nations (before that in fact- there were Model League of Nations simulations—which started, ironically, at Harvard, in the United States, which never joined the League), high school and university organisations have been running simulations of parts of the United Nations, generally called Model United Nations. These are designed to improve understanding of international affairs, build up public speaking skills and look good on a CV/resume.
Theoretically, at least. Most participants regard it as something fun to do: LARP in suits that you can put on your resume.
The Real Thing
Many, many examples, as well as those with a Fictional Counterpart. The United Nations name and logo is subject to legal restrictions. Some works upgrade the UN to a virtual world power with actual might to back its authority, while others go further and claim that it is or will become an actual One World Order. Usually this is accompanied by boatloads of Did Not Do the Research.
- Controls all the armed forces seen in Neon Genesis Evangelion. Obvious from the first scene, where the line of tanks seen along the waterfront all have UN painted in large white letters on the turrets.
- Likewise, in Super Dimension Fortress Macross, Earth is defended by the UN "Spacy", or in later sequels, the New UN Spacy. The Robotech adaptation of Macross has a similar organization, usually called the "United Earth Government" or the "United World Government" in spinoff fiction even though they write "UN Spacy" on all their mecha.
- The Interpreter- the only thing ever filmed in the real UN building. Someone dies.
- The Alfred Hitchcock film North by Northwest. Someone dies.
- The James Bond film Live and Let Die. Someone dies.
- Batman: The Movie has the "United World Council" which consists of a handful of delegates constantly shouting over each other.
- Left Behind.
- The upcoming documentary "U.N. Me" shows some of the more bad aspects of the U.N., especially in comparison to its founding ideals.
- In a plot-swinging United Security debate on North Korea's invasion of South Korea in Red Phoenix, the US Ambassador provides evidence of Soviet pilots flying against the US on North Korea's side, with Soviet backing. In the vote that follows, the US and USSR can't vote (they're parties to the dispute) and the Chinese, who were expected to veto a resolution on the matter as they're also arming North Korea, abstain. China eventually engineers a coup in the DPRK and a cease-fire.
- In Left Behind, the United Nations (now headed by the Antichrist) is portrayed as an organization that pretty much rules the world already.
- UNIT in Doctor Who. Originally stood for "United Nations Intelligence Taskforce", but when it was reintroduced in the new series the UN complained; as a result the acronym now means "Unified Intelligence Taskforce". It is said that they still receive some money from the UN though.
- The United Network Command for Law and Enforcement from The Man from U.N.C.L.E. and The Girl from U.N.C.L.E. was called this in significant part to avoid legal problems with the United Nations. However, both Canon and Fanon have it that U.N.C.L.E. is the go-to organization for problems that the United Nations itself isn't able to handle, or can't handle because of the restrictions imposed by its charter. One Fanfic (published in, of all places, the UN Secretariat's internal newsletter) even had a UN employee meeting Napoleon Solo in the tunnels beneath Manhattan!
- In the Twilight Zone episode "To Serve Man", the spokesman for the Kanamit aliens addresses the UN. He also leaves behind a book titled To Serve Man, which the story's famous Twist Ending reveals as a cookbook.
- In The Champions, the eponymous heroes are agents of Nemesis, a Fictional Counterpart of Interpol run by the UN.
- In GURPS, at least two alternate Earths are led (in all but name) by their United Nations: The main one from Infinite Worlds and the one from GURPS Supers (which got its own sourcebook, GURPS International Super Teams). In both there are still sovereign states that must be dealt with diplomatically, but the UN still has actual military power (but both are still mainly benevolent.)
- The United Nations in the Guilty Gear games, who host the original fighting tournament and place the bounty on Dizzy.
- The Liberty City-based Civilization Committee (CC) in Grand Theft Auto IV, a Fictional Counterpart of the UN, exists to indirectly make fun of the UN's shortcomings, being lambasted for its inefficiency in influencing international affairs, its organization of lavish banquets while parts of the world suffer from food shortages, and the failure of its members to pay parking tickets in the city. For that, the CC is "wisely" ignored by the American government, and the tourist-drawing view of the CC's Liberty City headquarters is described as more important than the organization based inside.
- In Civilization IV the UN is a buildable World Wonder that opens up a Diplomatic Victory, and more: all civs get to vote for the Secretary-General, who periodically can propose resolutions for ceasefires, adopting a global currency, open borders, mandatory civic choices, or a freeze on nuclear weapons manufacturing. In contrast with Real Life, these resolutions are totally binding even if you voted against them.
- The Beyond The Sword expansion revised this - players can now choose to defy resolutions at the cost of suffering relationship damage to other civilizations. The expansion also introduces the Apostolic Palace, which appears much earlier in the game (buildable with Theology, a tech that can usher in the Medieval Era - the UN is available with Mass Media, in the middle of the Modern Age) but only applies to those with a certain state religion (and the builder if they change or abandon the state religion).
- In the main Command & Conquer: Tiberium timeline, the United Nations founded the Global Defense Initiative, an international army, to protect the free world from international terrorism. After the arrival of Tiberium and the rise of the Brotherhood of Nod destroyed much of the planet, the GDI has pretty much become a One World Order.
- Deus Ex: The player works for UNATCO, a anti-terrorism organization and standing army for a future United Nations. It, and the rest of the UN are later revealed to be a front for MJ12 forcing the player to fight his former allies halfway through the game.
- In the Halo series, the United Nations has expanded into the United Nations Space Command when humanity invented the Shaw-Fujikawa Translight Engine.
- In Sid Meier's Alpha Centauri, the Peacekeepers are a combination of the remnants of the United Nations personnel and others devoted to democratic and humanitarian ideals on the starship Unity, united under one group when the population of the ship broke up into different ideological factions. They effectively form a new UN on Planet after landing, though they are effectively just one of the seven factions with no official control over the others. The Peacekeepers do, however, have serious political capital, giving them an edge in elections when an international council is eventually established (i.e. each other faction gets one vote per unit of population, while the Peacekeepers get two per unit of population).
- The United Nations was also briefly mentioned in Metal Gear Solid 4: Guns of the Patriots as being the guys partially responsible for the development of the War Economy (mostly due to the Patriots' machinations from Metal Gear Solid 2: Sons of Liberty). They were also revealed to have basically garnered world control after the destruction of the Patriots and SOP, namely because the world ended up broke with a debt so huge that, like Germany after World War I, not even PMC regulatory laws could come close to paying off the debt. It's also implied that this came with a negative: That the UN would basically become the Patriots' successor for world domination and control, and the process will happen all over again.
Online Roleplaying Games
- NationStates had a global organization called the United Nations, using the logo. The UN sent a cease-and-desist letter to Max Barry in 2008. Barry complied, changing the name to the World Assembly. He announced the change on 1 April 2008, in the process subverting the April Fools' Joke.
- Alternate History scenarios often include an alternate version of the UN. For example Monarchy World has the Assembly of Nations in Rosario, Argentina, while Gurkani Alam has the Oikoumene Council in Oranjeburg in the country that in our world is South Africa.
- Greendale had a Model United United Nations in one episode of Community the (il)logical result of a competition between two Model UNs. A few weeks later, Parks and Recreation (part of the same NBC block) followed suit with a Model UN that (among the few participating adults) dissolved into in-fighting, absurd treaties and personal vendettas, and South Africa/The Moon withholding gravity exportation.
- Springfield Elementary had a Model UN in one episode of The Simpsons. When the meeting dissolves into in-fighting and The Ditz singing "O Canada", Skinner tries to bring everyone to order:
Skinner: (Bangs his shoe on the table) Do you kids wanna be like the real UN, or do you just wanna squabble and waste time?
- The Vatican still hasn't, on moral grounds.
- one vote for the Soviet Union, one vote for the Ukraine and one for Byelorussia. Stalin originally wanted all sixteen of the Soviet Republics to get a vote--on the theory that the Soviet constitution was a treaty between sovereign states -- Harry S. Truman more or less said, "Well, the US Constitution was originally a treaty between sovereign states, so each one of the 48 (at the time) should get a vote." Stalin shut up after that, but the Ukrainian and Byelorussian SSRs got votes because the US was feeling nice and didn't want the USSR to feel that it was getting short shrift (the US had way more allies at the time than did the Soviet Union).