Leotychidas [Leotychides, Latychidas] (c. 545 BC–469 BC) was a ruler of Sparta 491 BC-476 BC. He led Spartan forces during the Persian Wars from 490 BC to 478 BC. He is not to be confused with the (allegedly illegitimate) son of Agis II, of the same name.

Born in Sparta around 545 BC, Leotychidas was a descendant of the house of Eurypontid and came to power with the help of Cleomenes I by challenging Demaratus for the throne of Sparta in 491 BC. Later that year, he joined Cleomenes' second expedition to Aegina, where ten hostages were seized and given to Athens. However after Cleomenes' death in 488 BC, Leotychidas was almost surrendered to Aegina. In the spring of 479 BC, Leotychidas commanded a Greek fleet consisting of 110 ships at Aegina and later at Delos, supporting the Greek revolts at Chios and Samos against Persia. Leotychidas defeated Persian military and naval forces at the battle of Mycale on the coast of Asia Minor in the summer of 479 BC (possibly around mid-August). In 476 BC, Leotychidas led an expedition to Thessaly against the Aleudae family for collaboration with the Persians but withdrew after being bribed by the family. Returning to Sparta he was tried for bribery, and fled to the temple of Athena Alea in Tegea. Sentenced to exile, his house was burned and his grandson Archidamus II became the ruler of Sparta. Leotychidas died some years later, around 469 BC.

*Andrew R. Burn, Persia and the Greeks: The Defense of the West 456-478 B.C., New York, 1962 *Peter Green, The Year of Salamis 480-479 B.C., London, 1970 *Simon Hornblower, The Greek World, 479-323 B.C., 3rd ed., London 2002