Castro is a surname of toponymic origin derived from the Latin word castrum, meaning "fortified place," "fortress," or "castle." It originally identified people who lived near a fortified settlement or who came from one of the many places named Castro or from localities whose names were derived from the same root.

According to E. De Felice, the surname is closely associated with numerous Italian place names, including Castro, Castrogiovanni (the historical name of Enna until 1927), Castronòvo, Castronuòvo, and Castrovìllari. As a result, many branches of the surname likely originated independently in different regions of Italy.

Distribution

De Felice notes that Castro is particularly common in southern Italy, while it is less frequent in central Italy and in the northeastern regions of Veneto, Friuli-Venezia Giulia, and Trentino-Alto Adige.

According to F. Miranda, the surname is present throughout Italy, with especially significant concentrations in Sicilia, Lombardia, Puglia, and Lazio.

In Sicilia, Castro is found in all provinces, with particularly strong concentrations in the provinces of Catania, Siracusa, and Palermo. Miranda also highlights notable clusters in the Enna area, especially in the comuni of Assoro, Agira, Leonforte, and Regalbuto.

Notes

De Felice observes that some southern Italian branches may derive from the Spanish surname Castro, which is also widespread in Spain. In such cases, the surname may reflect historical connections between southern Italy and the Spanish world during periods of Spanish influence and rule.

Miranda notes that in the Sardinian language the terms castro, castru, and castra can refer both to ancient fortresses and to nuraghi, the prehistoric stone towers that are among the most distinctive monuments of Sardinia. This reflects the long-standing association between the surname and fortified structures.

Castro is therefore a classic toponymic surname whose origins are linked to castles, fortified settlements, and place names derived from the Latin castrum.