Surname Koubiak (Koubiak 
, Кубяк 
) , worldwide, is a rare family name. The cognomen Koubiak is characteristic of Ukraine, where it is a rare surname, Russia, and Kazakhstan, where it is a very rare surname. In absolute terms, this name is the most popular in Russia, Ukraine, and France. Very seldom, Koubiak is the forename as well as the last name.