Monteverdi, Claudio Giovanni Antonio (1567-1643), Italian composer, the most important figure in the transition from Renaissance to baroque music. Born in Cremona, he studied music with Veronese theoretician Marco Antonio Ingegneri. At the age of 15, Monteverdi composed his first work, a set of three-part motets, and by 1605 he had composed five books of madrigals. He became interested in the experimental musical dramas of Jacopo Peri, who was music director at the court of the Medici family, and in similar works by other early composers. In 1607 Monteverdi's first musical drama, Orfeo, was produced. This opera, which surpassed all previous attempts at musical drama, was possibly the most important development in the history of opera and established it as a serious form of musical and dramatic expression.

Through skillful use of vocal inflection, Monteverdi sought to express emotion as it would be expressed in the highly charged speech of a great actor. The orchestra, considerably enlarged and varied, was used not merely as an accompaniment for the singers but also to establish the moods of the various scenes. The score itself contains 14 independent orchestral pieces. The public received Orfeo enthusiastically, and with his next opera, Arianna (1608), Monteverdi's reputation as an opera composer was firmly established. In 1613 he was appointed to one of the most important musical posts in Italy, choirmaster and conductor at Saint Mark's Cathedral in Venice. From this time on, Monteverdi wrote numerous operas many now lost, motets, madrigals, and masses.

In his sixth, seventh, and eighth books of madrigals 1614-38 he moved away from the Renaissance ideal of equal-voiced polyphony toward the newer styles emphasizing melody, bass line, and harmonic support as well as personal, or dramatic, declamation. In 1637 the first public opera house was opened, and Monteverdi, stimulated by the enthusiastic response to opera, wrote a new series of operas, of which two remain, Il ritorno d'Ulisse in patria and L'incoronazione di Poppe a (The Coronation of Poppa ea, 1642). Written in Monteverdi's old age, these operas contain scenes of great dramatic intensity in which the vocal and orchestral music accurately reflect the thoughts and emotions of the characters. They influenced many subsequent composers of opera and are still performed today.

Monteverdi died in Venice on November 29, 1643.