Myrtilus was the son of Hermes and an Amazon named Myrto. Sometime after leaving the Gargareans, he became the charioteer of King Oenomaus of Pisa in Elis, located on the northwest coast of the Peloponnesus.
On the eve of the fateful horse race that would decide the marriage between Pelops and Hippodamia, Myrtilus was approached by Pelops (or in some accounts, by Hippodamia) who wanted him to hinder the efforts of his master, Oenamaus, to win the race. Myrtilus was offered as bribe the privilege of the first night with Hippodamia.
Myrtilus, who loved Hippodamia himself but was too afraid to ask her hand of her father, agreed and sabotaged the king's chariot by replacing the bronze linchpins with fake ones made of bees' wax. In the ensuing accident Oenomaus lost his life, cursing Myrtilus as he died. Shortly thereafter Myrtilus tried to seduce Hippodamia, who ran crying to Pelops, although Myrtilus said this was the bargain. Enraged, Pelops murdered Myrtilus by casting him into the sea off the east coast of the Peloponnesus, which was later named the Myrtoan Sea in honor of the hero. His body was later recovered and brought in the temple of Hermes where it was honored with annual sacrifices. Some say that Myrtilus was transformed into the constellation of Auriga.