Agartha is a subterranean civilization made by large olm-people, spanning three Ages. It may refer to:

• EA Agartha, Pale Ones ← This one is guided by three oracular orders, and Olms, but only uses bronze.
• MA Agartha, Golem Cult ← This one has been colonized by humans, who revere the olm-like survivors and animate statues of them.
• LA Agartha, Ktonian Dead ← This one is entirely human, though its leaders are Necromancers who reanimate the ancient olm-like Oracles.

All three have Earth magic, and a plethora of summons (or constructs, and/or reanimations) uniquely available to them.