Demiurge is a major character in Just Kill Me. He sends the player into the dark realm to kill the Demon God. He is the true main antagonist of Just Kill Me.
He is the god of creation, and is able to create anything he desires. However, once something is created, he is unable to destroy it without the help of Destroyer. After Destroyer erases the concept of "eternity", Demiurge banishes him to a dark realm and steals his powers. After this, Demiurge sends countless humans to the dark realm in an attempt to slay Destroyer permanently. It is later revealed that Demiurge plans to destroy humanity for their destructive capability through the use of the alien virus Troy, and the true reason why he locked Destroyer in a dark realm and wanted to kill him.