San Fratello (Gallo-Italic: San Frareau, Sicilian: Santu Frateddu, Latin: Apollonia), formerly San Filadelfio, is a comune (municipality) in the Province of Messina in the Italian region Sicily, located about 110 km east of Palermo and about 90 km west of Messina. San Fratello borders the following municipalities: Acquedolci, Alcara li Fusi, Caronia, Cesarò, Militello Rosmarino, Sant'Agata di Militello. As of 31 December 2004, it had a population of 4,371 and an area of 67.1 km².

The name of San Fratello derives from three pious brothers Alfio, Cirino and Filadelfio. In their honour 10 May of every year is kept a festivity. The village was founded in the 11th century by Adelaide del Vasto, Roger I's wife. She came in Sicily together with Lombard colonists who spread their Gallo-Italic dialect which is still spoken in the village.

The comune's territory is part of the Nebrodi mountains and has had 2 major landslides of record. The first was in 1754 and a second large one in 1922. In February 2010, after a period of large amounts of rain in the region of Messina, another extensive landslide caused damage to homes. As a safety precaution, one-third of the population evacuated as of February 14.