The Olympians were the principal deities of the Greek pantheon, so named because of their residency atop Mount Olympus. They gained their supremacy in a ten-year-long war of gods, in which Zeus led his siblings to victory over the previous generation of ruling gods, the Titans. They were a family of gods, the most important consisting of the first generation of Olympians, offspring of the Titans Cronus and Rhea: Zeus, Poseidon, Hera, Demeter and Hestia, along with the principal offspring of Zeus: Athena, Apollo, Artemis, Ares, Aphrodite, Hephaestus, Hermes, and Dionysus. Although Hades was a major deity in the Greek pantheon, and was the brother of Zeus and the other first generation of Olympians, his realm was far away from Olympus in the underworld, and thus he was not usually considered to be one of the Olympians. Olympic gods can be contrasted to chthonic gods including Hades, by mode of sacrifice, the latter receiving sacrifices in a bothros (βόθρος, "pit") or megaron (μέγαρον, "sunken chamber") rather than an altar.
The canonical number of Olympian gods was twelve, but besides the (thirteen) principal Olympians listed above, there were many other residents of Olympus, who thus might be called Olympians. Heracles became a resident of Olympus after his apotheosis and married another Olympian resident Hebe. Some others who might be considered Olympians, include: the Muses, the Graces, Iris, Dione, Eileithyia, the Horae, and Ganymede.