Amastris (Ancient Greek: Ἄμαστρις; c. 340/39- 284 BC) also called Amastrine, was a Persian princess, and Tyrant-ruler of the city of Heraclea from circa 300 to her death.

[6] Through this marriage, Dionysus was able to greatly increase his wealth, expand his power, and improve the welfare and loyalty of his subjects.

Shortly after, they separated and Lysimachus married Arsinoe II, one of the daughters of Ptolemy I Soter, the first Pharaoh of Ptolemaic Egypt.

[8] She also founded a city named after herself, Amastris, shortly after 300 on the sea-coast of Paphlagonia through the fusion (synoecism) of four smaller towns: Sesamus, Cromna, Cytorus, and Tium.

[3] She was drowned by her two sons around 284[9][7] but the matricide was avenged by Lysimachus, who made himself master of Heraclea and put both Clearchus and Oxyathres to death.