Leonteus of Lampsacus (Greek: Λεοντεύς) was a pupil of Epicurus early in the 3rd century BCE. He was the husband of Themista, who also attended Epicurus' school.^[1] Such was the esteem in which they held Epicurus that they named their son after him.^[1]

Leonteus is described by Strabo, as one of "the ablest men in the city" of Lampsacus, along with Idomeneus.^[2] Plutarch describes a letter, written by Leonteus, in which Leonteus describes how Democritus was honoured by Epicurus "for having anticipated him in getting hold of correct knowledge," and how Epicurus originally proclaimed himself a "Democritean."^[3]