Nicias or Nikias (c. 470 BC – 413 BCE) is an Athenian politician and general during the period of the Peloponnesian War.

Nicias is a member of the Athenian aristocracy because he had inherited a large fortune from his father, which was invested into the silver mines around Attica's Mt.

Laurium.

Following the death of Pericles in 429 BCE, he becomes the principal rival of Cleon and the democrats in the struggle for the political leadership of the Athenian state.

He is a moderate in his political views and opposed the aggressive imperialism of the democrats.

His principal aim is to conclude a peace with Sparta as soon as it could be obtained on terms favorable to Athens.

He is frequently elected to serve as strategos (general) for Athens during the Peloponnesian War.

He leads several expeditions which achieve little.

Nevertheless, he is largely responsible for the successful negotiations which lead to the Peace of Nicias in 421 BCE.

Following the Peace, he objects to the ambitious plans of Alcibiades for advancing Athens' interests.Despite this, Nicias is appointed to participate in the Athenian invasion of Sicily.

The Athenian siege of Syracuse is nearly successful until the arrival of the Spartan general Gylippus, who turns the situation around so that the Athenians are themselves under siege.

Nicias leads his forces in a desperate attempt to escape by land.

However, they are cut off and he and his Athenian army overwhelmed and defeated.

Subsequently, Nicias is executed.

Historians consider that the failure of the Athenian intervention in Sicily was largely due to the inadequacy of Nicias’ military leadership.