I Am Legend by Richard Matheson
Richard Matheson's sci-fi/horror masterpiece may be best known for the movies it inspired, but the fact is that it is an absolute classic for a reason. It tells the story of a man named Robert Neville, who believes he is the last man on earth in a world where society has been completely destroyed by mindless vampires. He works by day to dig through civilization for supplies, and by night to fix all of his boarded windows and fortifications so he can survive through the night, while also trying to develop a vaccine for the vampirism. Seriously amazing stuff.
Scare Factor: 3 - A bit violent but not a lot of jump-out-at-you scares. Still creepy!