The daughter of the king Oenomaus of Pisa. Her father did everything to avoid his daughter getting married, and challenged all her suitors in a horserace. When they lost they were killed.
Pelops was the 20th suitor and with Hippodameias help he beat her father, who was killed in the process.
They got married and ruled Pisa, and had many children: Atreus, Thyestes, Dias, Cynosurus, Corinthus, Hippalmus, Hippasus, Cleon, Argeius, Alcanthous, Pittheus, Troezen, Nicippe, Astydameia, Lysidice, Sciron and Epidaurus.
One version tells us that Pelops had a son by a previos wife, Chrysippus. He loved him dearly, and Hippodameia had Atreus and Thyestes kill him out of fear that he would inherit the throne. Pelops then cursed both sons, and Hippodameia committed suicide.