The Peace of Callias was established around 449 BC between the Delian League (led by Athens) and Persia, ending the Persian Wars.

The peace was negotiated by Callias, an Athenian politician. Persia had continually lost territory to the Greeks after the end of Xerxes I's invasion in 479 BC, and by 450 they were ready to make peace. The Peace of Callias gave autonomy to the Ionian states in Asia Minor, prohibited the establishment of Persian satrapies elsewhere on the Aegean coast, and prohibited Persian ships from the Aegean. Athens also agreed not to interfere with Persia's possessions in Asia Minor, Cyprus, or Egypt (Athens had recently lost a fleet aiding an Egyptian revolt against Persia).

It is possible that the treaty never officially existed. Thucydides did not mention it, and Plutarch thought it had either been signed after the Battle of the Eurymedon in 466 BC, or that it had never been signed at all. In any case, there seems to have been some agreement reached ending hostilities with Persia, which allowed Athens to deal with the new threats from the other Greek states such as Corinth and Thebes. These conflicts arose when the other Greeks felt there was no longer a justification for the Delian League, which had developed from the Spartan-led Hellenic League that defeated Xerxes' invasion, as Persia was no longer a threat. As Athens demanded more and more tribute and exerted more control over its allies, the League became more of a true empire, and many of Athens' former allies began to rebel. Although Callias was also responsible for a peace (supposed to last for thirty years) with Sparta around 445 BC, the growing Athenian threat would eventually lead to the Peloponnesian War.

There was no direct fighting between the Greeks and the Persians after 450, but Persia continued to meddle in Greek affairs over the next twenty years, and was to become instrumental in securing a Spartan victory in the Peloponnesian War.