Cognomen Douko (Дуко 
, Douko 
) , around the globe, is a rare surname. The last name Douko is habitual in Belarus, where it is quite a rare surname, Bulgaria, and Kazakhstan, where it is a rare surname. Not in comparison with a country's population, it most frequently occurs in Eastern Europe, particularly Belarus, Russia, and Bulgaria. Very seldom, Douko is the forename as well as the last name.