Antonio Lucio Vivaldi (4 March 1678 – 28 July 1741) was an Italian composer, virtuoso violinist and impresario of Baroque music. Along with Johann Sebastian Bach and George Frideric Handel, Vivaldi is regarded as one of the greatest Baroque composers and his influence during his lifetime was widespread across Europe, giving origin to many imitators and admirers. He pioneered many developments in orchestration, violin technique and programmatic music. He consolidated the emerging concerto form into a widely accepted and followed idiom.

Vivaldi composed many instrumental concertos, for the violin and a variety of other musical instruments, as well as sacred choral works and more than fifty operas. His best-known work is a series of violin concertos known as the Four Seasons. Many of his compositions were written for the all-female music ensemble of the Ospedale della Pietà, a home for abandoned children. Vivaldi began studying for the priesthood at the age of 15 and was ordained at 25, but was given dispensation to no longer say public Masses due to a health problem. Vivaldi also had some success with expensive stagings of his operas in Venice, Mantua and Vienna. After meeting the Emperor Charles VI, Vivaldi moved to Vienna, hoping for royal support. However, the Emperor died soon after Vivaldi's arrival, and Vivaldi himself died in poverty less than a year later.

After almost two centuries of decline, Vivaldi's musical reputation underwent a revival in the early 20th century, with much scholarly research devoted to his work. Many of Vivaldi's compositions, once thought lost, have been rediscovered – in one case as recently as 2006. His music remains widely popular in the present day and is regularly played all over the world.