Archidamus II was a king of Sparta who reigned from approximately 469 BC to 427 BC. He was of the Eurypontid house.
His father was Zeuxidamus, (called Cyniscus by many Spartans) who died before his father, Leotychidas II, after having his son, Archidamus.
Leotychides, when Zeuxidamus was taken from him, married a second wife, named Eurydame, the sister of Menius and daughter of Diactorides. By her he had no male offspring, but only a daughter called Lampito, whom he gave in marriage to his grandson Archidamus.
Archidamus was one of the kings of Sparta in the years preceding the Peloponnesian War. His coolness and presence of mind are said to have saved the Spartan state from destruction on the occasion of the great' earthquake of 464 BC, but this story must be regarded as at least doubtful.
During the negotiations which preceded the Peloponnesian War, he did his best to prevent, or at least to postpone, the inevitable struggle, but was overruled by the war party. He invaded Attica at the head of the Peloponnesian forces in the summers of 431, 430 and 428, and in 429 conducted operations against Plataea.
He died probably in 427 BC, certainly before the summer of 426 BC, when we find his son Agis II on the throne.