Santo Stefano is an island in the Tyrrhenian Sea off the west coast of Italy, and part of the Pontine Islands. It has a circular shape, is less than in diameter, and is located east from the nearby island of Ventotene.

Santo Stefano is an island in the Maddalena archipelago of northern Sardinia, Italy, and part of the Maddalena National Park. It is largely uninhabited and it is mainly known for its hosting of a NATO Naval Base and Italian Navy munitions magazines Apart from the military, the only residences on the island is a tourist resort, Club valtur, which is largely occupied only during the summer months. Public access to the island is made by ferry either from La Maddalena or nearby Palau, on Sardinia.