Giovanni Battista Fontana (1589–1630) was an early Baroque Italian composer and violinist.

Fontana was born in Brescia, and worked there and in Rome, Venice, and Padua.  He also died in Padua during the plague of 1629–31.

Nearly all information on Fontana comes from the preface by Fr. Giovanni Battista Reghino to his posthumously published 18 sonatas (Sonate a 1.2.3. per il violino, o cornetto, fagotto, chitarone, violoncino o simile altro istromento, Venice: Bartolomeo Magni, 1641). They are among the earliest sonatas of this kind, consisting of six sonatas for solo violin/cornetto with continuo and 12 sonatas for one two and three violins and continuo, the latter group often including a demanding concertante part for bassoon or cello.