Year 411 BC was a year of the pre-Julian Roman calendar.

• The democracy of Athens is overthrown. A "Council of Four Hundred" is set up. * Phrynichus, the leader of the extremists, is killed. The traditional constitution is put back.
• The Athenian navy under Thrasybulus calls Alcibiades back from Sardis.

• Euripides' play Iphigeneia in Tauris is performed.
• Aristophanes' plays Lysistrata and Women Celebrating the Thesmophoria are performed.

• Timoleon, Greek statesman and general (approximate date) (d. 337 BC)

• Antiphon, Athenian politician and orator (b. 480 BC)
• Phrynicus, Athenian general (assassinated)