One of more frequent first (given) names among Croats is Franjo (Francis), which became popular due to the divine cult of Saint Francis of Assisi, a Catholic deacon who lived in late 12th and early 13th century, and who established the Order of Friars Minor also known as the Franciscans.
The Order’s monasteries were established throughout the region of today’s Croatia and Bosnia-Herzegovina in middle ages, thus spreading the glory of the name.
During times of the development of surnames among Croats, Francis of Assisi obviously had a prominent influence. There are quite a few Croatian family names with the root Franjo.
One form of this influence can be recognized in surnames like Franičević, Frančić, Franković, Franjić, Francetić. In areas where phonem F wasn’t recognized, variants Pranić, Prančić and Pranjić became popular. Another class of variants were Vrančić, Vranješ and Vranjković.
Motivation for creation of these surnames sometimes came from neighboring nations. Thus both in Slovenia and Croatia surnames like Franc, František, Frangeš, Francev can be found. Also, hungarian spelling Ferenc influenced creation of Croatian surnames Ferenčak and Ferenčić. From Germans, we picked variants Franc and Frank, and from Italians Frančeski, Franco and Francolić.