Pausanias (Ancient Greek: Παυσανίας) was the Agiad King of Sparta; the son of Pleistoanax. He ruled Sparta from 445 BC to 427 BC and again from 409 BC to 395 BC. He was the leader of the faction in Sparta that opposed the imperialist policy conducted by Lysander.
Pausanias became king in 445 BC, when his father Pleistoanax was forced into exile because he made a peace settlement with Athens, which was deemed dishonourable in Sparta. Too young to reign, his uncle Cleomenes acted as regent. Pleistoanax then returned in 427 BC and resumed his reign. Pausanias effectively became king in 409, at the death of his father. As he continued the conciliatory policy with Athens favoured by Pleistoanax, Pausanias clashed with Lysander, the Spartan general who had won the Peloponnesian War against Athens in 404 BC and supported an imperialist policy in the Aegean Sea. In 403 BC, Pausanias engineered the restoration of the Athenian democracy, which had been replaced by the regime of the Thirty Tyrants installed by Lysander after his victory. The latter's supporters and the other king Agis II attempted a prosecution for betrayal against Pausanias, who narrowly escaped condemnation.