Bank of International Settlements (BIS)
Based in Basel, Switzerland, the Bank of International Settlements is sometimes referred to as the “central bank of central banks” because of its history as the first genuinely global banking institution and the fact that it offers financial services to other central banks.
The BIS was established in the 1930s and has served many roles in its storied history, from being responsible for collecting and distributing German reparations payments after WWI to funding troubled nations during various debt crises.
The BIS fosters cooperation between central banks and is well-known by foreign exchange traders for its comprehensive triennial survey of foreign exchange and OTC derivatives trading. If you’ve ever come across a statistic on the size of the global FX market, it was probably quoted from a BIS report.