In Croatia, Koss families are Croats (from Mursko Sredisce ). In the past century, relatively most of Croatian residents bearing this family name were born in Slovenia.
Prevalence
Only a few people with faimily name Koss live in Croatia today, in one household only. There were 10 of them in the middle of the past century, and their number remains constant. They are located in two Croatian cities only, in Peklenica (<5) and Kutina (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned about one hundred times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.