Pherecydes of Syros was an early Greek thinker from the 6th century BCE. He is considered one of the first writers to compose in prose instead of poetry, marking a transition in how ideas were expressed. Ancient sources often describe him as a teacher of the philosopher Pythagoras, though the historical truth of this connection is uncertain.

He wrote on the origins of the gods and the cosmos, in a work sometimes called the Heptamychos ("Seven Recesses"). His writings survive only in fragments quoted by later authors. In his cosmogony, he used innovative mythological figures like Zas (a form of Zeus), Chthonie (Earth), and Chronos (Time) to explain how the world was ordered.

According to modern scholars, Pherecydes holds a significant place as a forerunner to Presocratic philosophy. While his work used myth, it was a systematic attempt to explain the world's origins, influencing later philosophical and religious traditions. He is remembered as an important bridge between earlier poetic mythology and the rise of rational inquiry in ancient Greece.