In Greek mythology, Antiope was an Amazon, daughter of Ares and sister to Melanippe, Hippolyta, Penthesilea, and possibly Orithyia. She is one of the figures linked to Theseus's Amazon adventure: in many accounts Theseus abducts her (or receives her from Heracles), marries her, and she bears Hippolytus; in others the Amazon bride is Hippolyta instead. Her death is variously ascribed to the Amazon Molpadia during an attack on Athens, or to Theseus himself after he abandoned her for Phaedra.
Adapted from Wikipedia, "Antiope (Amazon)" · CC BY-SA 4.0
I.Mythology
There are various accounts of the manner in which Theseus became possessed of Antiope, and of her subsequent fortunes. In one version, during Heracles' ninth labour to obtain the Girdle of Hippolyta, his companion Theseus abducted Antiope and brought her to Athens (or she was captured by Heracles and given to Theseus). According to Pausanias, Antiope fell in love with Theseus and betrayed the Amazons of her own free will. They married and she gave birth to a son, Hippolytus, named after Antiope's sister.
Soon after, the Amazons attacked Athens in an attempt to rescue Antiope and to take back Hippolyta's girdle; in a battle near the Areopagus they were defeated. During this Attic War, Antiope was accidentally shot dead by an Amazon named Molpadia, who was in turn killed by Theseus. The tombs of both were shown in Athens, according to Pausanias.
According to some sources, the Amazons attacked because Theseus had abandoned Antiope and planned to marry Phaedra. Antiope attacked on their wedding day and was slain by Theseus himself, fulfilling an oracle; Ovid mentions that Theseus killed Antiope even though she was pregnant. An alternative tradition transfers the whole story — abduction, marriage, Hippolytus, and abandonment — to Hippolyta rather than Antiope.