Cleinias (Kleinias) may refer to a number of people from ancient Greek history:
Members of the Alcmaeonidae family Cleinias, father of the Athenian statesman and general Alcibiades Cleinias, brother of Alcibiades, younger brother of the famous general Cleinias, son of Axiochus; he is introduced as a very young man by Plato in the dialogue called Euthydemus Cleinias of Tarentum, Pythagorean philosopher Cleinias of Croton, tyrant of Croton c. 495 BC Cleinias of Sicyon, magistrate of Sicyon c. 270-264 BC, father of Aratus of Sicyon. Cleinias of Crete, a cretan lawgiver who appears in Plato's Laws.