Archidamus I (flourished 7th century bc) was the 12th king of Sparta of the Eurypontid line. The son of Anaxidamus, he ruled shortly after the close of the second Messenian War (c. 660 bc) and toward the outset of the long war between Sparta and Tegea (the Tegean War). His reign was described by the geographer Pausanias as quiet and peaceful.