The zombie versions of
Marvel characters have drawn a lot of attention due to the
What If...? animated series promotional material. But they are actually not creations of the series. Originated in the comics, the concept had an entire series dedicated to them, giving rise to a whole new universe. The focus here is Earth-2149, where several superheroes have been infected, in a story that started in 2005 and explored in several comics since then. In this list, you can find out more about the origin of this universe, the reading order of the comics, and many other curious facts about
Marvel's Zombies! Concept

The concept presented in
Marvel's Zombies is very similar to that of classic zombie stories. However, Earth has experienced an apocalyptic plague in this universe, having its streets occupied by hordes of the living dead who feed on the living and spread their infection even further. In this dystopian reality, not even the superheroes could stay safe from the terrible transformation. In fact, they proved essential for the plague to spread, making the nightmare experienced by the inhabitants of this universe even worse.
First Appearance

Despite having a whole universe and series of its own, the zombie version of
Marvel's heroes was not developed like this from the beginning. The first appearance of the
Zombie universe happened in the
Ultimate Fantastic Four series, which started in 2004. The issue in which this happens is #21, written by Mark Millar. In the plot,
Reed Richards discovers the Zombiverse while exploring different dimensions. He encounters the zombie versions of the
Fantastic Four, who tricked him into opening the path from their dimension to Earth-2149. Early on, it is explained that to spread between dimensions, the virus seeks to infect superheroes. In just 24 hours, the zombie heroes have consumed virtually the entire world, with the only survivors being
Magneto and a small group of ordinary humans. In the comic,
Reed must deal with the zombies who now have a path to their dimension. So he and
Magneto join forces while
Sue,
Johnny, and
Ben confront the infected who try to consume their universe.
Miniseries

In 2005,
Marvel released a miniseries continuing the
Ultimate Fantastic Four events. However, with
Magneto managing to sever the link between the two universes, the plot turns its attention to the mutant, who discovers other survivors off-planet. Other characters are introduced, and the zombies themselves go through some changes throughout the story. However, as is clear from the beginning, they do not follow the common tradition of zombie stories where the infected lose their mental capacity since they can think, speak, and use their powers without any problems. The series was written by
Robert Kirkman, the author of
The Walking Dead, and illustrated by
Sean Phillips. In all, 5 volumes of the comic have been published.
Characters

At first, the highlight of the plot goes to
Magneto, presented initially as the only superpowered being to survive. However, as the story develops, it is revealed that
Black Panther has also survived without being infected, although the reason for this is not at all pleasant. That's because the zombie version of
Hank Pym had kept him trapped and hidden, slowly taking pieces of the hero to consume little by little. On the zombie side, the main characters are
Colonel America,
Iron Man,
Giant-Man,
Spider-Man,
Luke Cage,
the Hulk, and
Wolverine. The
Silver Surfer and
Galactus also end up appearing in the plot and significantly impact how everything ends.
Prequel

In 2007,
Marvel released
Dead Days, a comic telling all about the beginning of the zombie apocalypse. It is explained precisely how the virus originated, which heroes were the first to fall, and how the world reacted to it. The story is also written by
Kirkman and illustrated by
Phillips. In a single volume, it is told in detail how it all began and how the heroes tried to fight the apocalypse. In addition, the series features
Reed Richards and the development of the plan that connects the universe to his first appearance in the
Ultimate Fantastic Four comics.
Sequels

A sequel to the original series, called
Marvel Zombies 2, was published between 2007 and 2008. The series also has five volumes and was followed up in
Marvel Zombies 3, with four volumes. After that,
Marvel Zombies 4 was released as a four-volume limited series, starring the publisher's more horror-based characters. Thus, the cast of this plot comes from titles such as
Morbius,
The Thing,
Mephisto, and others. Finally, the series received a direct sequel in
Marvel Zombies 5, which has five volumes. After that,
Marvel Zombies Return picked up
Marvel Zombies 2, with five volumes that finalize the original zombie story. The series has also received a few spin-offs. Some of them take place in single, short stories, such as
Eat the Neighbors. Others are series that feature alternate versions of the Zombiverse, such as
Marvel Zombies Destroy, set during World War II.
Reading Guide

To read the history of this universe from the beginning, you need to start with the comics that initially introduced it. Thus, reading begins with
Ultimate Fantastic Four #21, in a mini-arc that continues in volumes 22 and 23. After that, following story order rather than release order, the next comic is
Dead Days. As explained, this is where it is shown how the Zombiverse apocalypse happened until all the heroes had succumbed. Only then does the original mini-series begin. Thus,
Marvel Zombies 1 is the next reading on the list, continuing the story of Magneto and the zombified heroes.
Marvel Zombies 2 continues the plot, taking place some 40 years after the original mini-series. However, this time, the living dead also contaminate space, with the story taking on cosmic dimensions. The next part of the zombie universe is in
Marvel Zombies 3. Here, the desperate struggle to reclaim humanity from the zombies resumes and is led by Michael Morbius. The publisher's robots also get their chance to fight, as they are immune to the virus and can go directly to the front lines of the Zombiverse.
Marvel Zombies Returns, another spin-off of the series, directly follows up on these events, picking up characters transported to other dimensions in year 2 of the main series. In this way, it is possible to read the comic after years 2 and 3, although it is also possible to leave it for the end. After that comes
Marvel Zombies 4, where a legion of monsters come to confront the zombies after humanity fails at this. These events are followed up in
Marvel Zombies 5, which also mixes western elements into the story. The other comics in the universe have no set order, as they are single, stand-alone stories. Thus,
Marvel Zombies Halloween, Destroy! and
Supreme can be read in any order.
In What If...?

It has not yet been confirmed how this universe will be portrayed in
What If...?, but the trailer released has already shown that zombie versions of major heroes will be present in the series. Among them, it has already been confirmed that there will be a zombie
Captain America (or Colonel America, if the Zombiverse is adapted),
Iron Man, and
Hawkeye. Characters seen in the comics will likely be replaced by others, as not all of the Zombiverse heroes from the comics have been featured in the MCU so far. Also, it is worth noting that the story in
What If...? may end up being completely different, taking inspiration from the original only through the zombie versions of
Marvel's heroes.