I am huge fan of E.E. Knight`s Vampire Earth series. The books are an incredible blend of sci-fi, horror, vampires, and action crossed with a Civil War/Western-style epic. I know that sounds crazy, but E.E. Knight pulls it off masterfully. Also, the vampires in this book are nothing like the traditional model, so don`t let the title discourage you. Vampire Earth is one of my favorite series, and I would recommend it to any sci-fi and action fan.