Silanion (Greek: Σιλανίων, gen. Σιλανίωνος) was the best-known of the Greek portrait-sculptors working during the fourth century BC. His floruit is given by Pliny (Naturalis Historia, 34.51) as the 113th Olympiad, that is, around 328–325 BC; the tradition recorded by Pliny was that Silanion had no famous teacher. Of two of his known works, however, his idealized portrait head of Plato was commissioned by Mithridates of Persia for the Academy of Athens, c. 370 BC, Of it and of an idealized portrait head of Sappho, later copies survive, if the number of surviving copies can be correlated to the fame of the commissions. Both are of simple ideal type, the Sappho not strictly a portrait, since Sappho (sixth century BC) lived before the age of portraiture. The best copy of the Plato is in the Glyptothek of Munich (illustration).
Silanion also produced a "portrait" of the poet Corinna. Other "portrait" heads by Silanion evoked mythic and legendary heroes. An Achilles mentioned by Pliny was later adapted to represent Ares, and an equally idealized Theseus is mentioned by Plutarch.
Silanion wrote a treatise on proportions that is mentioned by Vitruvius (vii, introduction).