Olympias (Greek: Ολυμπιάς) (c. 376/5 BC - 316 BC) was an Epirote princess, a wife of Macedonian king Philip II of Macedon and the mother of Alexander the Great. She was a strong believer in the god of wine, Dionysus, and often had snakes in her bed and around her neck.

Olympias was daughter of Neoptolemus, king of Epirus. Her father claimed descent from Neoptolemus, son of Achilles.

When her father, Neoptolemos, died (c.360 BC) his brother Arymbas who became king, made a treaty with the new king of Macedonia Philippos II (Philip of Macedon, 360 BC-336 BC). The alliance was cemented with a diplomatic marriage. Neoptolemos' daughter (Arymbas niece) Olympias became queen of Macedonia in 359 BC. It is said that Philip II had fallen in love with her when they were among the celebrants at the Kaveiria mysteries of Dionysus in Samothrace, where they were both being initiated into the mysteries.

Olympias, Gold medallion (Source)

The marriage was stormy and in the fall of 357 BC, Olympias being neglected and in anger went back to Epirus where she spent the winter. Late in spring of 356 BC, under pressure from her uncle the Epirotan king she returned to Pella -the Macedonian capital- pregnant. Alexander was promptly born late July, 356 BC. Philip, his wife not being a Macedonian, was scorned as not having a pure-blooded heir. Olympias obliged and with Epirotan pride, and insisted that she had got impregnated by Zeus while napping under an oak tree, the sacred tree of Zeus. Contemporary Zagorian sheepherders still take naps under oak trees. Alexander appeared to have believed the tale, as he later went to seek- and probably received -confirmation of his divine descent at the sanctuary of Zeus Ammon (of the sands) in the Siwa Oasis in Egypt.

The fickleness of Philip and the jealous temper of Olympias led to a growing estrangement, which ripened when Philip married a new wife, Cleopatra, in 337 BC. Alexander, who sided with his mother, withdrew, along with her, into Epirus, whence they both returned in the following year, after the assassination of Philip, which detractors of Olympias said she countenanced. During the absence of Alexander, with whom she regularly corresponded on public as well as domestic affairs, she had great influence, and by her arrogance and ambition caused such trouble to the regent Antipater.