3 Answers

There is actually more than one but if you mean for the USA, then this should explain it. 

The Federal Reserve System fulfills its public mission as an independent entity within government. It is not "owned" by anyone and is not a private, profit-making institution.

As the nation's central bank, the Federal Reserve derives its authority from the Congress of the United States. It is considered an independent central bank because its monetary policy decisions do not have to be approved by the President or anyone else in the executive or legislative branches of government, it does not receive funding appropriated by the Congress, and the terms of the members of the Board of Governors span multiple presidential and congressional terms.

However, the Federal Reserve is subject to oversight by the Congress, which often reviews the Federal Reserve's activities and can alter its responsibilities by statute. Therefore, the Federal Reserve can be more accurately described as "independent within the government" rather than "independent of government."

The 12 regional Federal Reserve Banks, which were established by the Congress as the operating arms of the nation's central banking system, are organized similarly to private corporations--possibly leading to some confusion about "ownership." For example, the Reserve Banks issue shares of stock to member banks. However, owning Reserve Bank stock is quite different from owning stock in a private company. The Reserve Banks are not operated for profit, and ownership of a certain amount of stock is, by law, a condition of membership in the System. The stock may not be sold, traded, or pledged as security for a loan; dividends are, by law, 6 percent per year. http://www.federalreserve.gov/faqs/about_14986.htm