Musaeus of Eleusis was a semi-legendary poet and religious teacher from the 6th century BCE. He is traditionally linked to the sacred rituals at Eleusis and is often described as a disciple or even the son of the mythical bard Orpheus, placing him within the inspired, mystical tradition of ancient Greek religion.

Ancient sources credit him with composing oracles, hymns, and a poem on the origin of the gods. However, none of these works survive intact. Their historical reliability is complicated because, according to the historian Herodotus, a compiler named Onomacritus was accused of editing and forging verses attributed to Musaeus in the 6th century BCE.

Despite the uncertain nature of his actual writings, Musaeus holds significant importance in Greek tradition. Modern scholars see him as a foundational link in transmitting Orphic religious ideas and theological poetry. He was considered a major authority on ritual practice and initiatory lore, especially for the Eleusinian Mysteries. His legendary status demonstrates how the name of an inspired poet-priest could carry great cultural and even political weight in the ancient world.