Cleonides (Greek: Κλεονείδης) is the author of a Greek treatise on music theory titled Εἰσαγωγὴ ἁρμονική Eisagōgē harmonikē (Introduction to Harmonics). The date of the treatise, based on internal evidence, can be established only to the broad period between the 3rd century BCE and the 4th century CE; however, treatises titled eisagōgē generally began to appear only in the 1st century BCE, which seems the most likely period for Cleonides' work.
- Jon Solomon, "Cleonides [Kleoneidēs]", The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell (London: Macmillan Publishers, 2001).
- Thomas J. Mathiesen, Apollo's Lyre: Greek Music and Music Theory in Antiquity and the Middle Ages (Lincoln: University of Nebraska Press), page. 366.
- English translation of the treatise by O.Strunk, at attalus.org