Alcidas (Ancient Greek: Ἀλκίδας) was a Spartan navarch during the Peloponnesian War.
He was first appointed to lead 40 allied ships in the Spartan expedition to Mytilene in 427 BC.
Thucydides states that this idea had merit, as the Spartans were "welcome everywhere", and the loss of Ionia would be a serious blow to Athenian resources.
[1] After these events Alcidas led his fleet to Cyllene and found that Brasidas had been sent to him in the capacity of "counsellor", showing the Spartan disapproval of his results at Lesbos.
Thucydides states that the Spartans wished to found this colony "because it would lie conveniently for the purposes of the war against the Athenians.