We Will Spend Credits in the Future

For some reason, possibly the widespread adoption of credit cards as a form of electronic currency, it has become convention that the unit of currency in futuristic and particularly Space Opera settings is called the "Credit". It's also a way to avoid using the name of any existing currency, which would tend to fall into Creator Provincialism or seem outdated as history marches on.

Accounting lectures in the future must be terribly confusing things. For fun try asking a real accountant what they think about naming a currency this in Real Life.

A subtrope of Global Currency, although not always.

Comic Books

 * Judge Dredd (known as "Creds" in street slang)
 * Their global status is very dependent on the writer of the story. Other, real world currencies have cropped up occasionally.
 * Strontium Dog

Film

 * Total Recall

Literature

 * The Foundation series by Isaac Asimov (well, less global than lenticular - it's used across the entire galaxy, except on one occasion where Asimov slips up and refers to "dollars" instead). Possibly the Trope Codifier?
 * Hex by Rhiannon Lassiter, which takes place in the 24th century, uses credits as currency worldwide. As everything is computerised at this point, this system may be the logical next step after the use of credit cards and nonphysical monetary transactions became common.
 * it's mentioned in The Comet's Curse that the world created a credit bank, making the quarter that they found incredibly rare.

Live-Action TV
"De Salle: "Maybe we can't break it, but I'll bet you credits to navy beans we can put a dent in it!""
 * Doctor Who (Galactic Credits)
 * Overdrawn at the Memory Bank
 * Star Trek: The Original Series. Often mentioned indirectly, as in the episode "Catspaw":

"Dylan : Oh we have plenty of currency. It's just that none of it's . . . current."
 * Star Trek: The Next Generation would ditch money altogether. Or, at least that was Gene Roddenberry's intention. That didn't stop Dr. Crusher from asking a merchant to charger her account on the Enterprise, though. In the first episode, no less. Maybe it was Early Installment Weirdness.
 * The UFP doesn't use money, but at that point the planet where the first episode of TNG was set wasn't a member of the UFP, so they might still have been using money, so obviously there needs to be some medium of remunerative exchange between Federation citizens and non-Federation citizens.
 * Quark charges money, despite him working on a Federation-controlled space station. In fact, as mentioned in one episode, he also has his own vouchers, which he claims are as good as latinum, only for Riker to point out that, while that may be true, Quark's vouchers are only good at his establishment, while latinum is valid tender almost anywhere.
 * Gene Roddenberry's Andromeda used to have this, but it went away with the fall of the Commonwealth.

Tabletop Games

 * Starfire: The costs for building starships are calculated in "megacredits" for all races/empires.

Video Games

 * In the X-Universe, the local Proud Merchant Race backed the creation of a single currency for the Commonwealth governments. Prior to this, each race used its own currency.
 * Deus Ex
 * Though Dollars are mentioned by name in the first game's dialogue, and menus in Paris apparently are in Pounds Sterling by 2054.
 * Escape Velocity
 * EVE Online has a little more complex a take on things. ISK (Inter-Stellar Kredits) is not so much a global currency as it is a global exchange currency. Planetary economies and sometimes individual planetary nations almost all have their own currencies, ISK was merely setup as an exchange medium to manage the obscene amounts of money being used at the inter-stellar level - the popular saying goes you can retire comfortably planet-side basically anywhere in the cluster on single digit amounts of the stuff.
 * Also, the game's publisher is Icelandic, and "ISK" is the International Currency Code for the Icelandic Krona.
 * Mass Effect - Similar to the EVE example. Every country/government/planet has their own currency, while "credits" are actually just a short hand exchange rate for money. There are several high powered accounting firms tasked with monitoring and adjusting exchange rates among every currency, so if you bought a gun your account would be subtracted dollars and they would be given ... whatever they use. Credits is just an easy way for everyone to get an idea of what prices are. They don't actually "exist" like money does.
 * One can imagine that money doesn't "exist" either in an interstellar civilization. We're already on the verge of replacing physical currency.
 * It's specifically mentioned that there was no universal currency until the Volus created the credit system, earning them an embassy on the Citadel, even though they're not an independent government.
 * Wing Commander
 * Master of Orion. The standard unit for Galactic governments is the "BC" or "Billion Credits".
 * Elite (and its successors).
 * Freelancer
 * Galactic Civilizations also has BCs ("billion credits") by virtue of you running an interstellar empire and using money for projects on planetary scales.
 * Neptunia
 * EarthGov in the Dead Space series uses credits as its currency.
 * Vega Strike (currently, at least) has even outlaws and aliens not allied with major human groups trade in Credits.
 * Hegemonia: Legions of Iron: "bc" stands for "billion credits"; make sense, since you're building spaceships and conducting massive colony enhancements.

Web Comic

 * Freefall, as seen here.

Web Original

 * Chakona Space uses Fed Creds. Galaxy-wide currency and e-currency.

Real Life

 * An interesting Real Life subversion: In coin-op video games, credits (not quarters) were the standard currency, but a credit was whatever coin was typically used in the localization. Of course, in Mortal Kombat, it was kredits.

Film

 * Demolition Man: "John Spartan, you are fined one credit for a violation of the verbal morality statute." We don't know quite how widespread the use of credits are, as San Angeles seems to be pretty independent from the rest of the USA.

Literature

 * Futuretrack Five mentions Eurocredits. Presumably a rough equivalent of the European Currency Unit, and what currencies the rest of the world use is never explored.

Live-Action TV

 * Babylon 5's only human currency is called credits.
 * In the Firefly 'verse, the Alliance's central planets use credits (paper bills or electronic transfer) as currency, and 1 credit is about equal to $25 US according to the RPG. The lower-tech outer planets mint their own coins from precious metals (typically silver, gold, and platinum, in ascending order of value), and also frequently use barter.

Tabletop Games

 * In Traveller, only the Imperium's currency is called credits.

Video Games

 * Secret of Evermore only uses credits in the Omnitopia section.
 * Many factions in the Star Wars franchise mint and back their own "credit" with varying acceptance. Credits are often on chits or coins, but in Marvel Star Wars, they looked like bills.
 * Knights of the Old Republic however has one "credit" that is used by everyone except the sandpeople, despite the civil war and weakness of the backing government.

Western Animation

 * Batman Beyond, as far as can be seen. Paper "Creds" don't even exist, it's all plastic cards.

Real Life

 * the-n.com, a now-defunct website run by Nickelodeon, used "creds" to buy gear for avatars. No, not that avatar. Or that one. Or that one. You got creds just for surfing, and you got them for snitching. Considered a Scrappy Mechanic by Degrassi the Next Generation fans who didn't go to the-n.com, but an obsession of the-n.com users.