The daughter of the Eurypontid king of Sparta, Archidamus (c. 469-427), and sister of Agesilaus
(who ruled from c. 399-360),
Cynisca won renown in her own name because of her entries into the Olympics. While Cynisca, as a woman, was forbidden to attend the main stadium at Olympia where running events and combat sports were held, she was not prevented from entering her 4-horse chariot teams into the equestrian events, twice -- so long as she did not participate herself. Even more noteworthy, she won in 396, and then again in 392. Cynisca caused to have erected a commemorative plaque boasting of her wins. Xenophon says that the plaque was Agesilaus' idea.
Source: The Spartans, by Paul Cartledge.