Some further remarks If I may add something from my sources A renowned Greek encyclopedia Helios ed  Volume Greece pages  presents as major gods the following Zeus Hera Athena Apollo Artemis Hephaestus Aphrodite Ares Hermes Demeter Dionysus Poseidon and Hestia It gives  major gods and does not include Hades I recall from my editing of Greek mythology during its successful FARC what I had written stating HW Stoll Religion and Mythology of the Greeks  The limitation of their number of the Olympians to twelve seems to have been a comparatively modern idea From a search in Google Book I get conflicted information For instance Encyclopedia Americana says that Hades was not one of the  and that Dionysus often displaces Hera In Gardners Art Through the Ages p  I see a list identical to the one Sthenel gives but it is also mentioned that Hades was of equal status In Lesley AdkinsRoy A Adkins Handbook to Life in Ancient Greece  I read According to Hesiod there were  Olympians Zeus Poseidon Hera Athena Apollo Artemis Aphrodite Hermes Demeter Dionysus Hephaestus and Ares So here Dionysus and Demeter are included but not Hades and Hestia In my version of Britannica CD ROM I did not find something helpful maybe somebody else can research there better I still have to check the most renowned modern Greek encyclopedia PapyrusLarousseBritannica but I think that the most comprehensive approach is the one I read in Religious Facts There were fourteen different gods recognized at some point as Olympians though never more than twelve at one time Zeus Hera Poseidon Ares Hermes Hephaestus Aphrodite Athena Apollo and Artemis were always considered Olympians Hestia Demeter Dionysus and Hades are variable gods among the Twelve I think that this is quite accurate there was a clear group of  major gods and some others included or not according to different sources and this is the spirit I think this article should reflect Now if there is a consensus towards this direction we can find out the exact wording maybe something similar to Religious Facts or any other helpful proposal include the necessary sources and references and close this issue