Lydiadas of Megalopolis () was an ancient Greek tyrant of his city Megalopolis in Arcadia. He came to power around the year 245 BC, but after ten years he decided to step down, leading his city to join the Achaean League. As a reward the Achaeans elected him to the post of strategos, that is (commanding general) of the League, for three terms in 234/33, 232/31 and 230/29 BC. In 227 BC he lost the elections against Aratus of Sicyon, but was chosen as hipparch, in this position he fell at the gates of his city during a cavalry charge against the Spartan king Cleomenes III. Biography Probably a son of Eudamus from Caphyae, Lydiadas was raised as a citizen of Megalopolis. Almost nothing is known of the steps by which he rose to power, but the sources represent him as a man of an ambitious yet generous character, who was misled by false rhetorical arguments to believe that a monarchical government was the best for his fellow-citizens. His elevation appeared to have taken place about the time that Antigonus Gonatas made himself master of Corinth (244 BC) Pausanias mentions him as one of the commanders of the forces of Megalopolis at the battle of Mantineia (c. 249 BC) against the Spartans under Agis As he was associated on that occasion with another general, Leocydes, it may be inferred that he had not then established himself in absolute power. If he came to power around 245 BC, he had held the position for power about ten years, when the progress of the Achaean League and the fame of its leader Aratus of Sicyon led him to form projects more worthy of his ambition. After the fall of the tyrant Aristippus of Argos, instead of waiting until he was attacked in his turn, Lydiadas determined voluntarily to abdicate as tyrant and permit Megalopolis to join the Achaean League as a free state. This generous resolution was rewarded by the Achaeans by the election of Lydiadas to the prestigious post of strategos or commander-in-chief of the confederacy the following year 233 BC. His desire for fame and his wish to distinguish the year of his command through some brilliant exploit led him to plan an expedition against Sparta, which was, however, opposed by Aratus, who is said to have already begun to be jealous of Lydiadas' favour and reputation. Lydiadas, indeed, proved