Palaephatus the Mythographer was a shadowy 4th-century BCE author. Ancient sources conflate him with other figures named Palaephatus, and a traditional identification as a companion of Artaxerxes is likely a later fabrication. Modern scholarship places his work in the late 4th century BCE based on linguistic evidence, though a Hellenistic date is also argued.

His sole attested work is Peri Apiston (On Unbelievable Tales), a rationalizing treatise surviving in an epitomized form. It systematically offers euhemeristic or naturalistic explanations for myths, arguing they originated from misunderstandings of historical events or language.

Palaephatus is significant for his systematic, rationalizing approach to mythology, representing a critical tradition that includes Hecataeus of Miletus and early Peripatetics. The surviving epitome of Peri Apiston was influential in the Byzantine period and later mythographic traditions.