Ariston of Chios was a Stoic philosopher active in the 3rd century BCE. He was a pupil of Zeno of Citium, the founder of Stoicism, and was known for his eloquent speaking style, which earned him the nickname "the Siren." After Zeno's death, he broke away from the mainstream Stoic school. He taught at the Cynosarges gymnasium in Athens. Some ancient sources suggest he was also a pupil of the philosopher Stilpo before studying with Zeno, though modern scholars do not universally accept this detail.

None of Ariston's own writings survive intact. Ancient sources mention titles of his works, such as Dialogues, Exhortations, and Anecdotes of Socrates, but these are all lost. His ideas are known only through fragments and reports in later authors.

Ariston was a significant but heterodox figure in early Stoicism. His main philosophical disagreement was with the standard Stoic curriculum. He rejected the traditional three-part division of philosophy into logic, physics, and ethics. According to modern scholars, he argued that only ethics was useful, dismissing logic and physics as beyond human concern. Within ethics, he focused narrowly on virtue and vice, considering other subjects like health or wealth—which Stoics called "indifferents"—as irrelevant to the wise person. This radical stance was criticized by later Stoic leaders. Although his influence within the Stoic school was limited, he is remembered as a brilliant, controversial thinker whose challenges helped shape the development of more orthodox Stoic doctrine.