One-sentence summary: A plague turns everyone on Earth into vampires except for one man.
Vampire lovers, reclaim the night! Throw off the chains of shitty YA romances, cast off your sparkly blinders, and see these creatures for what they really are: literary representations of humanity's oldest fears. Start with the original vampire apocalypse, Richard Matheson's I Am Legend.
One of the most influential vampire novels of the 20th century, I Am Legend regularly appears on the "10 Best" lists of numerous critical studies of the horror genre. As Richard Matheson's third novel, it was first marketed as science fiction (for although written in 1954, the story takes place in a future 1976). A terrible plague has decimated the world, and those who were unfortunate enough to survive have been transformed into blood-thirsty creatures of the night. Except, that is, for Robert Neville. He alone appears to be immune to this disease, but the grim irony is that now he is the outsider. He is the legendary monster who must be destroyed because he is different from everyone else. Employing a stark, almost documentary style, Richard Matheson was one of the first writers to convince us that the undead can lurk in a local supermarket freezer as well as a remote Gothic castle. His influence on a generation of bestselling authors--including Stephen King and Dean Koontz--who first read him in their youth is, well, legendary.
Written in 1954, I Am Legend been made into a movie three times, and like all such classics, you really should read the original to appreciate what Hollywood got right and (mostly) wrong. I imagine that The Passage (the other vampire apocalypse novel I reviewed recently) will probably be made into a movie as well. The difference is that The Passage is already a big, bloated entertainment blockbuster of pop culture, so Hollywood probably won't do too much damage to it.
1964's The Last Man on Earth (starring Vincent Price) was probably closest to the novel, plotwise, though it changed the name of the main character. In 1971's The Omega Man (starring Charlton Heston), Robert Neville, the last man on Earth, is an Army officer who fights albino mutants. 2007's I Am Legend (starring Will Smith) makes Neville a scientist (as in The Last Man on Earth). But in the book, Richard Neville was just a blue collar worker who discovered the bacteriological origins of the vampirism plague on his own, because he had nothing better to do.
The book is definitely more sci-fi than horror: it was one of the first to treat vampires "scientifically," with Neville carefully deducing by means of research and experimentation the reasons why vampires are bulletproof but harmed by sunlight, why they are repelled by crosses and garlic, and how the plague transmits itself. We've seen all the ideas in this book in a hundred iterations now, but the ideas still seem fresh when you read the original from which the cliches sprung. In fact, for a book that's over half a century old, this is one of the least dated classic sci-fi tales I've ever read. There are not very many things that mark it as a story that couldn't be taking place in the present day, other than the specific references to dates (it takes place in the mid-70s: twenty years in the future at the time it was written).
The most egregious thing Hollywood did to Matheson's story is changing the whole point of the title. Robert Neville does not become a legend because of his valiant fight against the vampire hordes. Explaining the meaning would require spoiling the ending slightly, but suffice it to say that it's darker and more ironic than Hollywood's more "heroic" version, just as the vampires in Matheson's novel turn out to be more complex than the mindless rage-zombies they are in the movies.
Matheson's writing holds up well. He's both an author and screenwriter and knows how to deliver a story with plenty of descriptive details and no fluff. If you aren't aware of who Matheson is, some of his other credits are What Dreams May Come (which became a rather crappy 1998 movie with Cuba Gooding, Jr. and Robin Williams), the classic Twilight Zone episode Nightmare at 20,000 Feet (starring a pre-Star Trek William Shatner), and the Trilogy of Terror, whose Zuni doll episode is probably one of the most-cited sources of nightmares for anyone who stayed up too late to watch TV in 1975.
Verdict: This is a classic for good reason. It's a quick and entertaining read that tells far more story in far fewer pages than its imitators. Anyone who likes science fiction, horror, or vampires should read it.