Cognomen Kasyanchyk (Касянчик 
, Kasyanchyk 
) , globally, is a rare surname. The surname Kasyanchyk is habitual in Eastern Europe, particularly Ukraine, where it is quite a rare surname, Belarus, where it is a rare surname, and Poland, where it is a very rare surname. Not in comparison with a country's population, it is the most numerous in Eastern Europe, particularly Ukraine, Russia, and Poland.