Špiljak families are Croats and they are mostly from Pregrada area. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Pregrada.
Prevalence
About 310 people with faimily name Špiljak live in Croatia today, in 140 households. There were 380 of them in the middle of the past century, and their number decreased by 20 percent. They are located in the most of Croatian counties, in 18 cities and 32 other places, mostly in Zagreb (90), Hum na Sutli in Pregrada area (40), Pregrada (30), Kutina (15), and in Prislin in Pregrada area (15).
Outside Croatia
Family name Špiljak (including: Shpilyak , Spiljak , Shpylyak and Speljak ) is present in 7 countries on two continents.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.