The Dark One Worm is a member of the Dark Ones, a race of trans-dimensional demons created by an unknown evil force during the beginning of time to end creation. It was born from the core of the planet Shuggazoom. While many of the Dark Ones still are trapped in their home dimension The Netherworld, countless others such as the Dark One Worm are sealed within the core of countless planets, waiting to be awakened to begin their mission to destroy the universe. Skeleton King, a devoted disciple to the Dark Ones created the Pit of Doom as a conduit to connect The Citadel of Bone and corrupted The Power Primate to awaken The Dark One from its slumber to destroy the universe. The Dark One Worm's antenna attaching to the back of Skeleton King's decapitated head to become the Skeleton King Worm.
The Dark One Worm is possibly inspired by Space Slug from Star Wars Episode V: The Empire Strikes Back and The Worm that Gnaws in the Night.