In Croatia, Kosier families are Croats (from Djurdjevac ). In the past century, relatively most of Croatian residents bearing this family name were born in Djurdjevac and Zagreb.
Prevalence
About 20 people with faimily name Kosier live in Croatia today, in 9 households. There were 20 of them in the middle of the past century, and their number remains constant. They are only located in in 6 Croatian cities, mostly in Zagreb (<10), Severovci (<10), Petrinja (<5), Rijeka (<5), and in Krk on the Island of Krk (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.