Not having read the 'the horror from the hills story', it's hard to name the exact main characters. However, it's common in such horror stories to have a protagonist who is new to the area of the hills and becomes the focus of the horror. There could also be an antagonist, which might be a supernatural being or a human with evil intentions related to the hills. And perhaps there are supporting characters like friends or family of the protagonist who also get involved in the events that unfold in the story.
Since I don't know the story, I can't say for sure. But it might have characters like a brave explorer who stumbles upon the horror in the hills, or a local who has some knowledge about the dark secrets there.
I'm not familiar with the 'the horror from the hills story' in detail, but it could have main characters such as a group of hikers who find themselves in the middle of the horror. There might also be a reclusive hermit who has been living in the hills and has some connection to the source of the horror. Another possible main character could be a scientist who is investigating strange phenomena in the hills and gets caught up in the terrifying events.