San Cassiano is a town and comune in the Italian province of Lecce and region of Apulia in south-east Italy.
San Cassiano may also refer to:
- San Cassiano, Venice, Roman Catholic church in Venice, Italy
- San Cassiano Altarpiece, painting by Antonello da Messina
- San Cassiano Formation, geologic formation located on the Southern Alps
- Teatro San Cassiano, first public opera theatre in Venice, Italy