The Central Bank (CB) of any country is the most important market participant for that country´s currency. The Central Bank officials, with their president/chairman at the top, hold the monopoly for the monetary policy of each country or economic zone. A perfect example of this being the Eurozone. They are the decisive factor for all long-term currency moves. Of course, there are other market participants in the forex market such as investors, speculators, hedge funds, second level banks etc., but they usually drive the market in the short to mid-term.