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a way to avoid using the name of any existing currency, which would tend to fall into Creator Provincialism or seem outdated as history marches on.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.

Examples of We Will Spend Credits in the Future include:

Credits as Global Currency

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

Doctor Who (Galactic Credits)
Overdrawn at the Memory Bank
Star Trek: The Original Series. Often mentioned indirectly, as in the episode "Catspaw":

De Salle: "Maybe we can't break it, but I'll bet you credits to navy beans we can put a dent in it!"

- 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.

Dylan : Oh we have plenty of currency. It's just that none of it's . . . current.

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^[when?], 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.

Credits that aren't Global Currency.