Lydiadas of Megalopolis (Ancient Greek: Λυδιάδας ὁ Μεγαλοπολίτης) or Lydiades (Λυδιάδης)[1] 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.