The Infinite Madness, also known as the One True God, the Ultimate Chaos, God, The All-Seeing Horror, and The Outer Darkness, is the origin of all Eldritch creatures and the ultimate example of antediluvian horror. It is the entirety of existence exists for one reason only: to imprison it. It's only goal is to devour The Cycle Of Everything, absorbing it into itself, so that it may finally escape it's prison.
No entity can fight the Infinite Madness, except not directly. All the other Omnipotents check under their beds for it at night. It is older than and can stand toe-to-toe with The cosmic eye and Kevin. The creator and The Destroyer is the only one more powerful than him. Some think the Un-Being and the Infinite Madness are related in some way. Some think the Un-Being is a offspring or servant of the Infinite, others think they are one and the same.
Despite the very description of Kevin, It (that is The Infinite Madness) is not part of him.
Also, to learn anything about the Infinite Madness is to go completely insane and mutate into a cosmic horror, so.....
It's fun having tentacles coming out of your everything, isn't it?