Castolus or Kastolos () was a town of ancient Lydia. Xenophon says that king Darius II appointed his son Cyrus the Younger, commander of all the forces that muster at the plain of Castolus (Castoli Campus; ÃÂñÃÂÃÂÃÂûÿῦ ÃÂõôïÿý).
The site of the plain of Castolus is fixed as the Burçak Ovasñ; the site of the town is unknown.