Hippias of Elis (/ˈhɪpiəs/; Greek: Ἱππίας; late 5th century BC) was a Greek sophist, and a contemporary of Socrates. With an assurance characteristic of the later sophists, he claimed to be regarded as an authority on all subjects, and lectured on poetry, grammar, history, politics, mathematics, and much else. Most of our knowledge of him is derived from Plato, who characterizes him as vain and arrogant.
Hippias was born at Elis in the mid 5th-century BC (c. 460 BC) and was thus a younger contemporary of Protagoras and Socrates. He lived at least as late as Socrates (399 BC). He was a disciple of Hegesidamus. Owing to his talent and skill, his fellow-citizens availed themselves of his services in political matters, and in a diplomatic mission to Sparta. But he was in every respect like the other sophists of the time: he travelled about in various towns and districts of Greece for the purpose of teaching and public speaking. The two dialogues of Plato, the Hippias major and the Hippias minor characterize him as vain and arrogant. The Hippias major (the authorship of this work by Plato is sometimes doubted) concerns the question about the beautiful, and purposely puts the knowledge and presumption of Hippias in a ludicrous light. The Hippias minor discusses the deficiency of our knowledge, and characterizes Hippias as ridiculously vain.