Last name Косер (Kozer 
, Косер 
) , across the world, is a rare surname. The last name Косер is habitual in Estonia, where it is quite a rare surname, Czechia, where it is a rare surname, and Poland. Not in comparison with a country's population, this name is the most popular in the United States, Czechia, and Poland. Very seldom, Косер is the forename as well as the last name.