Pelops (Ancient Greek: ΠέλοπαςPélopas) was king of Pisa and the ancestor of the Atreids. He was the son of Tantalus and a grandson of Zeus. He won his wife, Hippodamia, by defeating his father-in-law in a chariot race. He succeeded his father-in-law, Oenomaus, as king in Pisa. His children, the Atreids, would eventually rule all the Peloponessus, the large peninsula in southern Greece. His children frequently intermarried with the descendants ofPerseus.