Original: 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.
Simplified: Zeus, Hera, Poseidon, Ares, Hermes, Hephaestus, Aphrodite, Athena, Apollo, and Artemis are always considered to be Olympians. Zeus, Hera, Poseidon, Demeter, Hestia, and Hades are all brothers and sisters.