Olympias was the daughter of Neoptolemus I, king of the Molossians, a tribe in Epirus, and sister of Alexander I. Her family belonged to the Aeacidae, a well-respected family of Epirus, which claimed descent from Neoptolemus, son of Achilles.
Olympias apparently was originally named Myrtale. Later she may have been called Olympias as a recognition of Philip’s victory in the Olympic Games of 356 bc. Philip’s polygamy did not threaten her position until 337, when he married a high-born Macedonian, Cleopatra. Olympias withdrew to Epirus, returning after Philip’s assassination (336). She then had Cleopatra and her infant daughter killed. Olympias quarreled repeatedly with Antipater, regent of Macedonia during the early years of Alexander’s invasion of Asia, and eventually retired again, about 331, to Epirus. Upon the death of Antipater in 319 (Alexander had died in 323), his successor, Polyperchon, invited Olympias to act as regent for her young grandson, Alexander IV (Alexander the Great’s son). She declined his request until 317, when Antipater’s son Cassander established Philip II’s simpleminded son Philip III (Arrhidaeus) as king of Macedonia. The Macedonian soldiers supported her return. She put to death Philip Arrhidaeus and his wife, as well as Cassander’s brother and a hundred of his partisans. In response Cassander entered Macedonia and blockaded Olympias in Pydna, where she surrendered in the spring of 316. She was condemned to death by the Macedonian assembly, but Cassander’s soldiers refused to carry out the sentence. She eventually was killed by relatives of those she had executed.