Costanzo Festa (c. 1495 – April 10, 1545) was an Italian composer of the Renaissance. He is best known for his madrigals, but he also wrote sacred vocal music.

Not much is known about his early life. His birth date has been given as early as 1480 and as late as 1495. In 1517 he began employment with Pope Leo X as a singer, and his first verifiable work dates from 1514. A communication from 1543 indicates that he was too sick to travel with the Pope to Bologna, and he died in 1545. Evidently he lived in Rome most of his life, most likely serving in the Papal Choir.

Festa was one of the few Italians in the Papal Choir. He was a master of the Netherlands contrapuntal technique, however, and his importance to music history is as the one who first brought the two musical styles, the Italian and the Netherlandish, together. In addition, he was an obvious influence on Palestrina, who modeled many of his early works after his.

Most of Festa's madrigals are for three voices (in contrast to the other early madrigalist, Verdelot, who preferred five or six). He liked quick, rhythmically active passages in his madrigals; this may reflect an influence from the contemporary vocal form of the villanesca. In addition he wrote extended homophonic sections, showing somewhat less an influence from the contemporary motet, in contrast to the motet-like imitative passages found in Verdelot.

In addition to his madrigals, published mostly between 1543 and 1549, several collections of his sacred works were published during his lifetime, among them four masses, over forty motets, and numerous Magnificats and Marian Litanies (for two choruses, each with four voices). The style of his sacred music matches that of his secular: he is less fond of imitation and complex counterpoint for its own sake, and often writes purely homophonic passages. Since Rome was musically conservative compared to the rest of Italy (and Europe) at the time, and there was a strong reaction against counterpoint within two decades after his death (expressly stated by the Council of Trent), his stylistic bent may represent a foreshadowing of that event; perhaps he was responding to the taste and needs of his papal employer.