Luca Marenzio (also Marentio; October 18, 1553 or 1554 – August 22, 1599) was an Italian composer and singer of the late Renaissance.

He was one of the most renowned composers of madrigals, and wrote some of the most famous examples of the form in its late stage of development, prior to its early Baroque transformation by Monteverdi. In all, Marenzio wrote around 500 madrigals, ranging from the lightest to the most serious styles, packed with word-painting, chromaticism, and other characteristics of the late madrigal style. Marenzio was influential as far away as England, where his earlier, lighter work appeared in 1588 in the Musica Transalpina, the collection that initiated the madrigal craze in that country.

Marenzio worked in the service of several aristocratic Italian families, including the Gonzaga, Este, and Medici, and spent most of his career in Rome.