Emilio de' Cavalieri (c. 1550 – 11 March 1602), or Emilio dei Cavalieri, the spellings "del" and "Cavaliere" are contemporary typographical errors, was an Italian composer, producer, organist, diplomat, choreographer and dancer at the end of the Renaissance era. His work, along with that of other composers active in Rome, Florence and Venice, was critical in defining the beginning of the musical Baroque era. A member of the Roman School of composers, he was an influential early composer of monody, and wrote what is usually considered to be the first oratorio.