Stefano Sposetti (born 22 December 1958) is a Swiss amateur astronomer and a prolific discoverer of minor planets. He lives in Gnosca, in the Italian-speaking part of Switzerland in the Ticino Alps, where the Gnosca Observatory is located.
Sposetti took images of 2004 FH, an Aten asteroid that made a sub-lunar flyby of Earth. In addition, he detects the optical counterparts of gamma-ray bursts and conducts transit photometry on exoplanets at his observatory.
As of 2019, Sposetti's discoveries include 164 minor planets (numbered only). The Minor Planet Center ranks him 70th in the list of all-time, worldwide discoverers. Asteroid 22354 Sposetti has been named after him.