In Croatia, Košek families are Croats (from Garesnica ). In the past century, relatively most of Croatian residents bearing this family name were born in Garesnica.
Prevalence
About 10 people with faimily name Košek live in Croatia today, in four households only. There were 10 of them in the middle of the past century, and their number remains constant. They are located in only two naselja i to in Sesvete (<10) and Zagreb (<10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.