Answer:
The antagonist of this book is the children of the corn's leader Isaac; who obsessively support a supernatural being called "he who walks behind the rows." He who walks behind the rows is later revealed as the driving force behind all of the evil in this story.
This should at least get you started, I would like to give you more but I wouldn't want to tell you wrong. I hope this helps! Good luck!
I have only seen the movie, and skimmed through the book. So, please look into the details before you submit.