Marathus was the leader of the Arcadian contingent of the army of the Dioscuri (Castor and Pollux) against Athens. According to some accounts, it was he, not Marathon, who gave his name to the city so called.

We must look to 'fennel', marathron, again for this name. Robert Graves points out that fennel stalks were used ritually for carrying the sacred fire from the central hearth to private hearths at the end of every year.