In Greek mythology, Myrtilus (gr. Myrtilos, Μυρτίλος) was a divine hero, a son of Hermes on Theobula, and charioteer of King Oenomaus of Pisa in Elis, on the northwest coast of the Peloponnesus.

On the eve of the fateful horse race that would decide the marriage between Pelops and Hippodameia, Myrtilus was approached by Pelops (or alternatively, by Hippodameia) 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 Hippodameia.

Myrtilus, who loved Hippodameia himself but was too afraid to ask her hand of her father, agreed and sabotaged the king's chariot by replacing the bronze lynchpins with fake ones made of bees' wax. In the ensuing accident Oenomaus lost his life, cursing Myrtilus as he died. Shortly thereafter Myrtilus made a pass at Hippodameia who ran crying to Pelops. 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.

As Myrtilus died, he cursed Pelops. This was the source of the curse that haunted future generation of Pelops' children, including Atreus, Thyestes, Agamemnon, Aegisthus, Menelaus, Orestes and Chrysippus.