Best Unexpected Zombie DLC
Originally released in October of last year (standalone released in November), the "Undead Nightmare" downloadable content for Red Dead Redemption was a real surprise. I didn't expect a Western-style shooter to release a zombie-based DLC. It only goes to show the influence and lasting impression that zombie-kind has on the weak (but delicious) minds of living humans.
If Rockstar decided to do this for the Red Dead series, then why not Grand Theft Auto? I could definitely see a post-apocalyptic GTA...or better yet, a living dead version of Manhunt.