I've spent the last few months travelling around Europe and during that time I listened to a lot of audiobooks (easier to read when driving or lying on the beach) and maybe because of my own recent output they were almost all about serial killers. I read about Richard Ramirez, Ted Bundy, Fred and Rose West, and Charles Manson. All were fascinating, all were terrifying, but what I learned listening to those stories is that there is nothing more terrifying than the truth, and nothing more monstrous than the human being. No matter how many flesh eating monsters or demon birds I dream up, none of them will ever be as horrifying as the things that occur in those true accounts for the very fact that they happened to real people, and real families.
I may review the books I read here in the future, but in the meantime you can listen to Helter Skelter, The True Story Of The Manson Murders for free (ad supported) on Youtube.
ps - Fred and Rose West were the worst of the bunch.