I can't give you all the deities, monsters, and heroes provided in the book (way to many), but here are the pantheons covered:
American Indian Mythos
Arthurian Heroes
Babylonian Mythos
Celtic Mythos
Central American Mythos
Chinese Mythos
Cthulhu Mythos
Egyptian Mythos
Finish Mythos
Greek Mythos
Indian Mythos
Japanese Mythos
Melnibonean Mythos
Newhon Mythos
Nonhuman's Deities (including Moradin, Corellon, Loth, Maglubiyet, Gruumsh, etc.)
Norse Mythos
Sumerian Mythos
The term ‘mythos’ is neutral enough. It is appropriate to refer to an ‘Arthurian mythos’. As many scholars do (ethnographers, mythographers, Jungian psychologists, and so on).
But to describe certain Native American tribes as having a ‘pantheon’, is ignorant, verging on offensive.
The term ‘pantheon’ is literally a Hellenistic term with tons of Hellenistic baggage. Its meaning is inappropriate to describe many Nonhellenistic cultures.
Because of historical forces relating to Christianity and Islam, Hellenism today influences swaths of the human species. Nevertheless, Hellenists lack the right to tell an other culture what it believes.
To a some degree, this list in the Deities & Demigods is a misappropriation of other peoples cultures. Especially, if there is little interest to understand or self-identify with these cultures.
To turn Africa into Tarzan or Scandinavia into Conan ... can go wrong.
I want D&D and D&D players to be able to handle reallife spiritual traditions − including Judaism, Christianity, Islam, Buddhism, and others. I would probably add Communism as a sacred philosophical tradition.
But to do this, must come with sensitivity and respect ... and real facts.
Consider how reallife Hinduism is presented in the exact same way as Chthulu.
If Deities & Demigods ever exists again, it probably wont look the same.