In Greek mythology , the Twelve Olympians are the major deities of the Greek pantheon , commonly considered to be Zeus , Hera , Poseidon , Demeter , Athena , Apollo , Artemis , Ares , Aphrodite , Hephaestus , Hermes and either Hestia , or Dionysus .
Zeus , Hera , Poseidon , Ares , Hermes , Hephaestus , Aphrodite , Athena , Apollo , and Artemis are always considered to be Olympians .