People who hail from the Mediterranean island of Sicily, which today belongs to Italy. Sicilians have a very diverse cultural heritage which is more than just merely Italian, hence the distinction that some often make between Sicilians and Italians. In addition to Italian ancestry/cultural influence, Sicilians also have Greek, Phoenician, Arab, Norman, French, and Spanish ancestry/cultural influences.
As such, Sicilians are arguably ethnically distinct from Italians, despite the fact that Sicily is part of Italy and its people are nowadays Italian-speaking Catholics. Due to the heavier Greek ancestry and also the presence of Phoenician/Arab ancestry, Sicilians are known for being somewhat darker than most other Italians, and have more pronounced Mediterranean facial features (i.e. fuller lips, thicker eyebrows, larger noses, etc.). However, Sicilians may also have blond/red hair, light eyes, and fair skin courtesy of Norman, French, or northern Italian ancestors. Still other Sicilians look like an average Italian (brown hair/hazel eyes and "Roman" features).
Although most Sicilians today speak standard Italian, the traditional Sicilian language was considered by linguists to be different enough from standard Italian to be its own Romance language, albeit with Greek, Arab, French, Spanish, and other influences due to the many conquerors/settlers that arrived in Sicily.
1st guy: Al Pacino is probably the greatest Italian-American actor of all time. And that Maria Grazia Cucinotta model chick is soo hot!!
2nd guy: No they're really not Italians actually, but Sicilians. For the record, Joe DiMaggio was also Sicilian-American.