Kolja is a male name, in Croatia principally Croatian, but also Albanian, Serbian and Romany. It is one of the relatively common names (among the top two thousand) in Croatia, with over a hundred namesakes living there.
The relative popularity of names Kolja in Croatia
The name Kolja was the most popular from years 1946 to 1951, when about 25% of the persons bearing this name were born. The peak year was 1947.
Prevalence
Name Kolja is relatively more common in the south of the country. Most of the persons named Kolja live in the following cities and municipalities: Split (about twenty), Zagreb (less than twenty), Beli Manastir (less than ten). Relatively speaking, the city with the highest percentage of namesakes is Grožnjan (0.13% of total population).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.