Giovanni Maria Trabaci (ca. 1575 – 31 December 1647) was an Italiancomposer and organist. He was a prolific composer, with some 300 surviving works preserved in more than 10 publications; he was especially important for his keyboard music.
Trabaci was most noted for his keyboard works, which include ricercares, canzonas and toccatas collected in two publications. His bold harmonic language, with unexpected modulations to distant keys, and experiments with structure in these works influenced Girolamo Frescobaldi. He also wrote numerous sacred vocal works, but these are, in general, more conservative. His 1602 book of motets, Motectorum, features advanced harmonic writing and may have influenced Carlo Gesualdo's 1603 Sacrae cantiones.