Marchetto di Padua [Marchetto da Padova, Marchettus de Padua] was a music theorist. From 1305 to 1307 he served as maestro di canto at the Cathedral of Padua; from 1308 resident in various other Italian cities, including Cesena and Verona.
Marchetto di Padua's principal theoretical works are Lucidarium and Pomerium. These treatises provide the most complete known 14th-century explanation of Italian trecento theory. The Lucidarium, which covers the basics of traditional music theory and of plainchant, includes an original and highly influential section setting forth a division of the whole tone into five parts. The Pomerium deals with mensural music, emphasizing notation in the Italian manner. Both were widely known and were claimed as authorities, quoted, or argued against, by many later writers.