Nicias , (470 - 413 av. J. - C.), was a politician and general Athenian.

After the death of Périclès, at the beginning of the Peloponnesian War, it became one of the political leaders in Athens, opposed to Cléon; its opinions are moderate and it does not support the aggressive imperialism of its city, preferring to aim at a fast peace with Sparte.

It is mainly responsible for the peace of 421 which bears its name, and which for a time suspends the hostilities.

Although he disapproves ambitious the forwarding of Sicily, he is placed at his head, like strategist, with Lamachos and Alcibiade, in 415. After the recall of Alcibiade and the death of Lamachos, he remains the only chief.

He falls seriously sick then, and, in spite of the arrival of Démosthène in 413, with reinforcements, the Athenians have serious problems. He will refuse a long time to withdraw himself by sea and its hesitations will be expensive the Athenian task force. In a desperate but too late attempt at retirement per overland route after the destruction of its fleet, its troops are pursued and decimated. It must then go and will be carried out later. Its execution will be required by Syracusains because some, close to betraying their city whereas the Athenian forces were main play, fear now that he speaks and loses them.

Nicias was one of the richest men of Athens. He was admired by his contemporaries, including by the historian Thucydide, for his uprightness and his virtue.