Palaephatus (Greek: Παλαίφατος) was the original author of a rationalizing text on Greek mythology, the work of paradoxography On Incredible Tales (Περὶ ἀπίστων (ἰστορίων) Peri apiston (historion); Latin: Incredibilia), which survives in a (probably corrupt) Byzantine edition.
This work consists of an introduction and 52 brief sections on various Greek myths. The first 45 have a common format: a brief statement of a wonder tale from Greek mythology, usually followed by a claim of disbelief ("This is absurd" or "This is not likely" or "The true version is..."), and then a sequence of every-day occurrences which gave rise to the wonder-story through misunderstanding. The last seven are equally brief retellings of myth, without any rationalizing explanation.
Palaephatus' date and name are uncertain; many scholars have concluded that Palaephatus is a pseudonym; the evidence, such as it is, is all of it consistent with the late fourth century BC.
Palaephatus' introduction sets his approach between those who believe everything that is said to them and those more subtle minds who believe that none [of Greek mythology] ever happened. He sets up two premises: that every story derives from some past event, and a principle of uniformity, that "anything which existed in the past now exists and will exist hereafter"; this he derives from the philosophers Melissus and Lamiscus of Samos. So there must be some probable series of events behind all myth; but the "poets and early historians" made them into wonderful tales to amaze their audience. Palaephatus then claims to base what follows on personal research, going to many places and asking older people what happened.
Palaephatus is a genus of moths in the Palaephatidae family.