According to E. Rossoni, the surname Villani —of pan-Italian diffusion— and its form Villano, more concentrated in the south (southern Lazio, Campania, Basilicata, Calabria and Sicily), may have a double origin. On the one hand, they could derive from the numerous place names formed on the root Villa, which would indicate a geographical provenance. On the other, they may be linked with the medieval term villanus, documented already in texts of the 13th century, which designated the inhabitant of the countryside as opposed to the citizen. This term gave rise to nicknames that later became surnames. Among the illustrious bearers stands out Giovanni Villani, author of the Nova Chronica of Florence, who died in 1348 during the plague.

For his part, F. De Laurentiis agrees in pointing to its wide diffusion throughout Italy, with a greater frequency in the north, Tuscany and the Naples area. He interprets the surname as derived from the medieval nickname Villano, meaning "one who lives in the countryside" or "inhabitant of small rural centres", and also, in a figurative sense, "peasant" or "rustic person". He adds that, in some cases —especially in the north-east—, it may also reflect a toponymic origin from localities called Villa.

F. Miranda comments that it is a pan-Italian surname, diffused in more than 1,240 Italian municipalities; it has large nuclei in Apulia, Campania, Lombardy, Emilia-Romagna and Lazio and more modest nuclei in the other regions, Tuscany, Piedmont, Veneto, Abruzzo and Liguria. In Sicily it is present in almost all the provinces, in particular in the Catania area (13 municipalities: Catania, San Giovanni La Punta, Mascalucia), Messina (8 municipalities: Lipari, Milazzo, Messina), Trapani (Mazara del Vallo, Trapani, Castelvetrano, Valderice) and Enna (Enna, Catenanuova). The surname was formed from the term villano, a medieval byname of one who lived in the countryside, as opposed to one who lived in the borough, who was called castellano. It could also derive from the various place names that have villa as their root.