Leotychides, king of Sparta (c.545-469, r.491-) was a successful commander during the Greco-Persian Wars, and commanded the Greek army at the battle of Mycale.
Leotychides (or Leotychidas) was a member of the Eurypontid dynasty. He succeeded his cousin Demaratus to the Eurypontid throne in Sparta in 491, after Cleomenes I had bribed the oracle at Delphi to declare Demaratus illegitimate. The trigger for this coup was a disagreement over the correct approach to take to the Persian threat to Athens. Athens was involved in a war with their near neighbours at Aegina. Cleomenes wanted to help Athens by taking hostages from Aegina and using them to force an end to the war. Demaratus opposed this policy and encouraged Aegina. After being deposed Demaratus went into exile, and accompanied the Persian invasion of 480 BC.
Cleomenes and Leotychides took their hostages, but the plan soon unravelled. The bribery at Delphi was made public. Cleomenes fled into exile, was recalled and went made. Leotychides was handed over to the Aeginetans, but won his freedom with an unsuccessful bid to get their hostages back from Athens. He returned to Sparta and continued his reign.
In 479 Leotychides was given command of the Greek fleet, which was then operating off the coast of Asia Minor. At first he remained largely inactive in the Aegean, with a fleet of 110 ships. At about the same time the Athens joined him, doubling the size of his fleet, and envoys arrived from Samos asking for support. This encouraged him to cross the Aegean. He caught up with the Persian fleet at Mycale on the coast of Lydia. The Persians refused to fight on sea and landed. Leotychides landed a little further to the east, turned back west, and defeated the Persians on land. This victory allowed the Greeks to liberate the cities of Ionian. Leotychides himself returned to Sparta, and was replaced by the controversial Spartan commander Pausanias.
In 476 Leotychides led an army to Thessaly to punish the Aleuad family for their support of the Persians. He withdrew before defeating them, and was charged with accepting a bribe. He was tried and convicted at Sparta and fled into exile at Tegea in Arcadia. He was formally exiled and his house was destroyed. He was succeeded by his grandson Archidamus II.