In the world of comics, a Marvel Zombie is a person solely devoted to the comic book publishing company Marvel Comics. They live and breath Marvel and its characters with a glossy glaze to their eyes and the only thing they crave is a Marvel comic. Other comics mean nothing to them, and only the likes of Spidey, Cap, The X-Men, and more will satisfy their thirst.
Marvel Zombies are the die hard fans of the Marvel Universe and the thought of comics from other publishers churn their stomachs. They typically follow many Marvel comics at once and will often purchase all the crossovers.
I was a total Marvel Zombie growing up, but now I've expanded my horizons.