Myrsilus of Methymna was a Greek historian from the city of Methymna on Lesbos, active in the 3rd century BCE during the Hellenistic period. No further biographical details concerning his life or education are preserved.

He is known for a single, now fragmentary, work titled Lesbiaca, a history of the island of Lesbos. The work is lost and survives only through quotations in later authors. Myrsilus is significant as a representative of Hellenistic local history.

His Lesbiaca was consulted by later writers like Athenaeus and Stephanus of Byzantium as a source for the island’s history, myths, and customs. His fragments contribute to the study of regional historical writing in the Greek world.