Who composed a mass that contained only pure liturgical polyphonic music?

The composer who is often associated with creating a mass that contains only pure liturgical polyphonic music is Giovanni Pierluigi da Palestrina. His compositions, particularly the "Missa Papae Marcelli," exemplify the ideal of a polyphonic mass that adheres closely to liturgical texts, ensuring clarity and reverence. Palestrina's work is celebrated for its balance between complexity and accessibility, making it a cornerstone of Renaissance sacred music.