From Wikipedia
The Twelve Olympians, , in Greek mythology, were the principal gods of the Greek pantheon, residing atop Mount Olympus. The first ancient reference of religious ceremonies for the 12 Olympians is found in the Homeric Hymn to Hermes. The classical scheme of the Twelve Olympians (the Canonical Twelve of art and poetry) comprises the following gods: Zeus, Hera, Poseidon, Demeter, Ares, Hermes, Hephaestus, Aphrodite, Athena, Apollo, Artemis, Hestia. The respective Roman scheme comprises the following gods: Jupiter, Juno, Neptune, Ceres, Mars, Mercury, Vulcan, Venus, Minerva, Apollo, Diana and Vesta.