The gods of Greyhawk are spelled out in canon
Which canon? Not in the folio. First in a series of Dragon articles in 1982-83; then in the boxed set (1984). And there was no suggestion that these lists were complete (eg Gygax himself added new gods in his own play: the Silver Key of Dalt is just one example).
Which canon? The folio and boxed set have a sage describing the visible heavens. That's all.
The portion of the Greyhawk Boxed set that discusses astronomy mechanics discuss the two moons, also as if there are only two moons.
To be fair, given the context of the celestial article, the sage is discussing all notable celestial objects. He describes the stars, the zodiac, the 5 wanderers, and two moons. Contextually, he only knows of two moons and five wanderers. It doesn't mean there aren't more he hasn't noticed, but it would be poor reading to infer there are other visible objects in the sky that he didn't enumerate.
Nagol is correct here; hence Maxperson is wrong. There is no discussion of moons as if there are only two. There is a discussion of visible heavenly phenomena, as if there are only two moons visible.
This leaves open the possibility of a third moon that is not visible - perhaps even an invisible black moon!
a third hidden moon couldn't remain hidden from a population that pays attention to astronomy as Greyhawk does. It would block out stars as it travels, and a travelling hole would have been noted long before the time of the boxed set and been noted within it.
We could not have missed a moon, and neither could the inhabitants of Greyhawk. The ancients of our world noticed pinpoints of light that moved in a funny manner and discovered planets. It would not be possible for people who pay attention to the heavens to miss a huge black hole in the sky that wandered around hiding stars and planets.
They failed to miss a moving dot, but you expect them to miss a massive moving black hole that blots out masses of stars. If you really believe that they could have missed a moon that did that, I have several bridges to sell you, starting with the Golden Gate Bridge and ending with the Brooklyn Bridge.
There are planets that the ancients did not spot, because they are not visible to the naked eye (not quite the case for Uranus, but near enough.)
There are currently satellites that orbit the earth that are not visible to the naked eye.
Hence there is no reason why Oerth could not be orbited by a small black moon that is not visible to the naked eye. (I have no idea on what basis you are talking about a "huge black hole in the sky" when I have repeatedly referred to a small black moon that is invisible to observers.)
The boxed set does in fact discuss moons other than the observations of the sage. It discusses them under Astronomical Phenomena.
The boxed set has no account of astronomical phenomena other than the passage from the sage. It is the same as in the folio.
The folio, at least as you have quoted it, does not say "at least" two moons.
(1) It doesn't say "two moons", either. It doesn't enumerate the moons at all. It just describes two of them, with an implication that the sage has described all he is familiar with. Which leaves it open that their may be moons with which he is not familiar.
(2) I infer from this that you do not have a copy of the folio. Which reinforces my curiosity as to how familiar you are with Greyhawk, and on what basis you are expounding forth on what is or is not consistent with GH canon, especially GH canon c 1990.
pemerton said:
Folio canon leaves this open. Later canon does not - it establishes that he is an Animus.
I was not aware of that. That means that yes, making him a lich would be a change in canon. Not sure why you'd want to make that change, though. I just Googled Animus and it's very much like a lich already.
This further reinforces my curisoity as to how familiar you are with Greyhawk. For instance, if you had to Google "Aninmus" that suggests that you don't have From the Ashes. We've already established you don't have the Folio. It seems you may not have the original boxed set. What is your basis for making all your confident assertions about what is or is not consistent with Greyhawk canon?