Although South Slavic names to a foreginer look and sound indiscernible in terms of nationality, that perception isn’t quite correct.
Members of South Slavic nations can often at glance discern whether someone’s first (given) name, as well as their surname is of particular’s national origin.
Scholars agree that the Great Schism in 1054 which divided medieval Christianity into two opposing branches (which later became known as Roman Catholic Church & Eastern Orthodox Church) played a major role in the development of different naming formulas among Croats and Serbs.
Before the Schism, the pool of names from which newborns were named had been pretty much the same for both nations. But the separation of two Christian branches caused greater Roman and Frankish influences among Croats, whereas Serbs were more influenced by Old Greek & Hebrew cultures.
Confequences of the Great Schism
Croats, because of their Catholic confession, often used names of Catholic saints for naming their children, either in the original Latin form (Benedikt, Dominik, Katarina, Donat, Klement, Lovro, Martin, Urban, Valentin etc) or through a mediating language like Italian (Alfonso, Bernardo, Bruno, Paško, Renata, Roman), French (Rolando, Agneza, Francisko, Leonora), German (Marta, Adalbert, Karlo, Leopold, Vilim) and others. Names in those forms are rare or nonexisting among Serbs.
On the other hand, Serbs accepted names derived from Old Hebrew and Greek: Atanas, Akcentije, Filotije, Arkadije, Nikifor, Jevrem, Timotej, Todosije, Konstantin/Koča etc.
Surnames reflected those differences accordingly. Thus surnames like Valentić, Lovrić, Bernardić, Frančić, Karlović can be considered typically Croatian, whereas surnames like Tanasković, Jevremović, Kočić, Jeftić, Aćimović, Aleksić are typically Serbian.
Image: Cassowary, Wikimedia Commons