Cynisca or Kyneska (Greek: Κυνίσκα; born c. 440 BC) was a Greek princess of Sparta. She became the first woman in history to win at the ancient Olympic Games.

Cynisca was born around 440 BC in the ancient Greek city of Sparta and was the daughter of the Eurypontid king of Sparta, Archidamus II, and Eupoleia. She was also the sister of the later king of Sparta, Agesilaus II. She is said to have been a tomboy, an expert equestrian and very wealthy, the perfect qualifications for a successful trainer. She was exceedingly ambitious to succeed at the Olympic Games and the first woman to breed horses and win an Olympic victory, according to Pausanias.

Her name means 'female puppy' in Ancient Greek. She was named after her grandfather Zeuxidamus, who was called Cyniscos. It is possible that this name related to a specific kind of dog in Sparta, the female bloodhounds of which were famous for their ability to find the quarries via their scent.

While most women in the ancient Greek world were kept in seclusion and forbidden to learn any kind of skills in sports, riding or hunting, Spartan women by contrast were brought up from girlhood to excel at these things so as to produce strong children, by going through early training similar to that of their brothers.