In Croatia, Mužjak families are Croats (from Grubisno Polje area ). In the past century, relatively most of Croatian residents bearing this family name were born in Grubisno Polje area and in Bjelovar.
Prevalence
About 10 people with faimily name Mužjak live in Croatia today, in 6 households. There were 30 of them in the middle of the past century, and their number decreased significantly. They are located in only four naselja i to in Bjelovar (<10), Zagreb (<5), Veliki Grdjevac in Grubisno Polje area (<5), and in Prgomelje (<5).
Outside Croatia
Family name Mužjak (including: Muzjak , Muzyak ) is present in four countries.
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.