Johann Philipp Sack (c. 1700–c. 1770) was a German composer and music theorist primarily known for his contributions to the Baroque and early Classical music periods. He worked in a variety of genres, including sacred music, chamber music, and instrumental compositions. Sack’s notable works include a collection of keyboard sonatas and various orchestral pieces that reflect the stylistic transition from the Baroque to the Classical era. Sack is perhaps best recognized for his treatise on music theory, which provided insights into the practice and pedagogy of music during his time. This work contributed to the understanding of harmony and counterpoint, influencing the teaching of music in the 18th century. While not as widely known as his contemporaries, Sack's impact lies in his role as an educator and theorist, helping to bridge the gap between Baroque traditions and the emerging Classical styles. His works, although not extensively performed today, offer valuable insights into the musical practices of his era, and he remains an important figure in the study of early German music.