There are two ancient persons with this name.
Musaeus of Athens is said to have invented the hexameter and was considered a universal genius. However, it is not proven whether he existed at all. Supposedly he was a contemporary/son/student of Orpheus, which would make him a mythological figure, except that no myths are known about him.
Musaeus was a late ancient poet. Around 500 he wrote the epyllion Hero and Leander.
In the Renaissance, no distinction was made between the two. Hero and Leander was considered one of the early lyrical works of the Occident, created by someone who had sat next to Orpheus. Hence Musaeus was mentioned in the same breath as Homer and Hesiod.1
- Braden (1978)↩︎