Azathoth is an overdeity that was formed from The Creator's discarded destructive side several billions of years ago. It is a non-sentient force of chaos that has the potential to destroy the entire multiverse. Azathoth currently resides in the Abyss, a plane at the center of the multiverse where it continues to create new worlds only to destroy them.
Knowledge of Azathoth in the multiverse is repressed by the Elder Gods as they believe that it can lead to insanity among most sapient species. However, there are many who are not only aware of Azathoth, but also worship it. In the Necronomicron and related texts, it is known as the "Daemon Sultan" and the "Blind Idiot God."
Azathoth's body is orbited by several worlds including Yuggoth, home to the Great Old Ones. Several Great Old Ones play music in Azathoth's prescence, believing that if they every stopped, Azathoth would consume them all. Their leader, Nyarlathotep , interprets the will of Azathoth and searches for followers throughout the multiverse. Occasionally, he will destroy entire universes in his master's name.
It is said that if the Creator passes away, Azathoth will break free and consume the multiverse itself. In that situation, the Elder Council's plan is to call on every sentient being in the multiverse, regardless of intelligence or moral standing, to help them create a spirit bomb that might kill Azathoth. They do not know if this would work since not even Eru himself is sure how to destroy a being on Azathoth's scale of power.