In Croatia, Otto families are generally Croats (from Ivanic-Grad area ), rarely Slovaks (from Ilok ). In the past century, relatively most of Croatian residents bearing this family name were born in Virovitica.
Prevalence
About 10 people with faimily name Otto live in Croatia today, in 7 households. There were 10 of them in the middle of the past century, and their number remains constant. They are located in 6 Croatian counties, four cities and threee other places, mostly in Novoselec in Ivanic-Grad area (<5), Zagreb (<5), Rijeka (<5), Ilok (<5), and in Hvar on the Island of Hvar (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.