The Devourers of G.

The Devourers of G. (Full name: The Devourers of God), Have been behind the plot this entire time. They made Black Warrior evil, they summoned Glass Brother, and later Bill Cipher. GB and BW were taken out by Orange Warrior, while BC was taken out by Crimson Warrior, who ended up dying from a Power Overdose. At the climax of Chapter 5, Orange Warrior finally discovers The D.O.G. And the final boss will be against The Warrior Eater, which is born from summoning Black Ghost.