These stories aren't the sheet-twisting, nightmare-giving type. They are get-in-your-head and under-your-skin type. The entities in this book will live in your mind long after you've read it. Read this book only if you want to be truly unnerved.
HP Lovecraft's The Colour Out of Space;
Thomas Ligotti's Songs of a Dead Dreamer and Grimscribe;
HP Lovecraft's The Call of Cthulhu