In Croatia, Grom families are Croats (from Samobor ). In the past century, relatively most of Croatian residents bearing this family name were born in Samobor and in Slovenia.
Prevalence
About 20 people with faimily name Grom 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 located in only two naselja i to in Samobor (20) and Samoborski Otok (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1924 in source Emigration Commission Zagreb.