Silvestro di Ganassi dal Fontego, also given as Sylvestro di Ganassi dal Fontego, Silvestro Ganasi dal Fontego, and Silvestro dal Fontego (1 January 1492 – 1565) was a Venetian musician and author of two important treatises on instrumental technique.

His first treatise covers recorder playing: Opera intitulata Fontegara (Venice, 1535). His second (in two volumes) is about the viola da gamba: Regola Rubertina (Venice, 1542) and Lettione Seconda (Venice, 1543). They cover both technicalities of playing and the subtleties of expression. There is also guidance on ornamentation—passaggi.

The revival of interest in historically aware musical performance has resulted in renewed interest in Ganassi's writings. His treatises are now available in modern editions.