The Great Wheel

Dungeons & Dragons' cosmology: a set of outer planes arranged in a ring by moral alignment, an astral plane crossed to reach them, and an ethereal plane between the world and everything else.

The most-used cosmological diagram in the English-speaking world after the Kircher Tree, and its ancestry runs through ☬ Wing L rather than ✥ Wing J. Astral and etheric as names for layered planes of existence are Theosophical vocabulary — Leadbeater's and Besant's — carried into pulp fantasy and then into a rulebook in 1977. Every player who has ever said "on the astral plane" is speaking nineteenth-century occultism, and not one in a thousand knows it.