Nodens

One of the Thirteen, beings whose existence predates the creation of our universe. The Thirteen were the only survivors from the prior existing universe which was destroyed in order to create 'our universe'. For this reason they have a great hatred of 'God' and especially human kind. They are known to attempt (often successfully) to destroy iterations of earth across the shared multiverse known as the 'Levels' accessed via the 'Labyrinth'. Nodens in particular is associated with Darkness, and is said by some to be the most powerful of the Thirteen. He is known to enshroud entire planets in his 'form', which is fatal to all living things on the planet. It is possible to counter his influence and to stop him from manifesting before he reaches a certain stage of power. However, the knowledge of how to do this is known to very few,

Quotes
"That’s right! They are very powerful. But the most powerful among them is He Who Shall Not Be Named. It is alive—a living darkness, and it goes from world to world, gobbling each planet up like gumballs. That’s what happened on Mars, you know. It used to be just like Earth. People lived there, and they were shiny and happy, until the darkness came and sucked their planet dry. A few of them made it out before the end, but not many." - Dez, the Darkness at the Edge of Town

“I kept it out. That’s all. I confined it to the edges of town. But we can’t make it go away. That’s impossible. Early on, before it completely breached our world, we could have. It’s been done before, on different Earths. But not now. The darkness is too strong now. It’s consumed too much.” - Dez, the Darkness at the Edge of Town