Musaeus the Grammarian was a late antique poet active in the early 6th century CE, likely during the reign of Emperor Anastasius I. The title "Grammarian" signifies his profession as a teacher of literature. Possibly a student of Nonnus of Panopolis, he was part of the Greek poetic culture in the Eastern Roman Empire, perhaps in Alexandria or Constantinople.

His only surviving work is the short epic Hero and Leander, a 343-line poem composed in Homeric hexameters. Musaeus represents a late flourishing of the ancient Greek epic tradition. His polished narrative of the tragic love story maintained popularity in Byzantium and later profoundly influenced Renaissance literature, serving as a key example of sustained pagan mythological themes within a Christian era.