Pherecydes of Leros (//; Greek: Φερεκύδης ὁ Λέριος; c. 450s BC) was a Greek mythographer and logographer. He came from the island of Leros. Pherecydes spent the greater part of his working life in Athens, and so he was also called Pherecydes of Athens (Greek: Φερεκύδης ὁ Ἀθηναῖος): the encyclopedic Byzantine Suda considers Pherecydes of Athens and of Leros separately.
Pherecydes of Leros should not be confused with Pherecydes of Syros, the mid-6th-century philosopher, who was sometimes mentioned as one of the Seven Sages of Greece and was reputed to have been the teacher of Pythagoras.
Pherecydes's great treatises—a history of his native isle, Leros (Περὶ Λέρου); an essay, On Iphigeneia (Περὶ Ἰφιγενείας); and On the Festivals of Dionysus (Περὶ τῶν Διονύσου ἑορτῶν)—are all lost. However, numerous fragments of his ten-book genealogies of the gods and heroes, which was written in the Ionian dialect to glorify the ancestors in the heroic age of his 5th-century patrons, have been preserved. Pherecydes modified the legends, not in order to rationalize them, but rather to adjust them to popular beliefs. Therefore, Pherecydes cannot be classed with the earlier mythographer Hecataeus of Miletus, whose Genealogiai ("Genealogies") were more skeptical and critical.