Sant'Alessio Siculo (Sicilian: Sant'Alessiu Sìculu) is a comune (municipality) in the Metropolitan City of Messina in the Italian region Sicily, located about east of Palermo and about southwest of Messina.
Its main attraction is a castle built in the 11th century by the Byzantine emperor Alexios I Comnenos in his war against the Normans and the Arabs, who also held it. It sits on the promontory Capo Sant'Alessio overlooking the sea and beach.