Lysias (/ˈlɪsiəs/; Greek: Λυσίας; c. 445 BC – c. 380 BC) was a logographer (speech writer) in Ancient Greece. He was one of the ten Attic orators included in the "Alexandrian Canon" compiled by Aristophanes of Byzantium and Aristarchus of Samothrace in the third century BC.
According to Dionysius of Halicarnassus and the author of the life ascribed to Plutarch, Lysias was born in 459 BC, which would accord with a tradition that Lysias reached, or passed, the age of eighty. This date was evidently obtained by reckoning back from the foundation of Thurii (444 BC), since there was a tradition that Lysias had gone there at the age of fifteen. Modern critics, in general, place his birth later, ca. 445 BC, and place the trip to Thurii around 430 BC.
Cephalus, his father, was a native of Syracuse, and on the invitation of Pericles had settled at Athens. The opening scene of Plato's Republic is set at the house of his eldest son, Polemarchus, in Piraeus. The tone of the picture warrants the inference that the Sicilian family were well known to Plato, and that their houses must often have been hospitable to such gatherings. Further, Plato's Phaedrus opens with Phaedrus coming from conversation with Lysias at the house of Epicrates of Athens: he meets Socrates, with whom he will read and discuss the speech of Lysias he heard.