In Greek Mythology, Eris is the (little known) sister of Ares and Hephaistos, daughter of Zeus. She is the goddess of discord and strife, and was indirectly responsible for the Trojan war.

From the Encyclopaedia Britannica: When she alone of the gods was not invited to the marriage of Peleus and Thetis, she threw among the guests a golden apple inscribed “For the most beautiful.” Hera, Athena, and Aphrodite each claimed it, and Zeus assigned the decision to Paris, then a shepherd on Mount Ida. Paris awarded the apple to Aphrodite, who then helped him win Helen of Troy. In the war that resulted, Hera and Athena remained implacable enemies of Troy.