Teraphobia is defined as the fear of monsters. It's common in children and some adults. I spent most of my childhood fearing every kind of monster. As I got older and reasonably recently I decided to build a world that makes that fear real.
The world is a post-apocalyptic United States. Five years out from an event called the Resurrection. The Resurrection was an event that created a multitude of new creatures. These creatures tipped the scale of human dominance and led to war and insurrection.
From the Resurrection, three new species of humans appeared.