Košec families are Croats and they are mostly from Zlatar area. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Zlatar area.
Prevalence
About 90 people with faimily name Košec live in Croatia today, in 40 households. There were 90 of them in the middle of the past century, and their number remains constant. They are located in four Croatian counties, four cities and 10 other places, mostly in Marija Bistrica in Zlatar area (20), Zagreb (20), Hum Bistricki in Zlatar area (10), Sesvete (<10), and in Gajec (<10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.