Ion of Chios (/ˈaɪɒn/; Greek: Ἴων ὁ Χῖος; c. 490/480 – c. 420 BC) was a Greek writer, dramatist, lyric poet and philosopher. He was a contemporary of Aeschylus, Euripides and Sophocles. Of his many plays and poems only a few titles and fragments have survived. He also wrote some prose works, including a Pythagorean text, the Triagmos, of which a few fragments survive.