Giorgio Mainerio (c. 1530s – 3 or 4 May 1582) was an Italian musician, composer, and occultist. He started his career as a presbyter and would only later start his musical career in the 1560s. Most of the songs he composed were in the 1570s and were mainly church music. He dabbled in occultism and was later investigated for it. Before his death, he suffered from health issues.