31 January or 22 March 1517 – 4 February 1590

His early education was with the Franciscans, and he later joined the order himself. In 1536 he was a singer at Chioggia Cathedral, and by 1539 he not only became a deacon, but also principal organist.

While he was a moderately prolific composer, and his motets are polished and display a mastery of canonic counterpoint, his principal claim to fame was his work as a theorist. While Pietro Aaron may have been the first theorist to describe a version of meantone, Zarlino seems to have been the first to do so with exactitude, describing 2/7-comma meantone in his Le istitutioni harmoniche in 1558. Zarlino also described the 1/4-comma meantone and 1/3-comma meantone, considering all three temperaments to be usable.

https://en.wikipedia.org/wiki/Gioseffo_Zarlino