Although doubtless one of Marvel’s most iconic antagonists, X-Men’s Magneto proved that deep down, he is a hero thanks to the Marvel Zombies. There has been an ongoing debate between fans about the man formerly known as Erik Lehnsherr and if his morals and beliefs about mutant superiority justify his controversial and at times destructive actions. While currently a believer in Xavier's dream of mutant/human peace as one of Krakoa's Quiet Council, Magneto became a full-blown protector of humanity (and whole realities) in the Marvel Zombies universe.
Magneto’s experiences with human hatred and cruelty in the Holocaust convinced him that their coexistence with mutants was impossible and thus he sought to conquer humanity so mutants could become the dominant species on Earth. Magneto and his followers frequently battled Charles Xavier and his X-Men, and his later plans became so world-threatening that other Marvel heroes like the Avengers or Spider-Man would occasionally get involved. Magneto’s beliefs would make him a controversial figure in the public eye with some condemning him and others idolizing him - some supporters even being those Magneto sought to dominate. Over the last decade or two, Magneto’s allegiance with the X-Men has made him more of an anti-hero; a powerful mutant who can fight alongside his former enemies to save the world, but is not afraid of getting his hands dirty. A similar version of Magneto is introduced in the Ultimate Fantastic Four “Crossover” storyline, which sees Reed Richards tricked into traveling to the parallel Marvel Zombies reality.
In the story arc by Mark Millar and Greg Land, Reed Richards is chased by the Marvel Zombies version of the Fantastic Four, eluding them only to run into a group of zombified and hungry superhumans. Reed is fortunately saved by Magneto who not only acts different than the Magneto he knows but is also the last living superhuman on Earth. He takes Reed to an underground hideout where a few uninfected humans remain, eagerly waiting the results of Magneto’s supply run. Magneto is not only the groups protector but cares for them, going on medical and supply runs even when the benefits don't concern him. Magneto admits that he realizes the irony of becoming humanity's final protector, but that "the end of the world is a great leveler." Ultimately, Magneto gets the final humans to a dimensional teleporter, sacrificing himself to deconstruct it and stop the zombies using it to invade Earth-1610.
Magneto's care for those under his care is clearly sincere, despite the fact they're human, though it could be argued this transformation comes about because of guilt. Magneto’s role in the infection that takes over his Earth is elaborated on further in Marvel Zombies: Dead Days by Robert Kirkman and Sean Phillip. This prologue shows that Magneto helped Patient Zero, a zombified version of the Sentry from another dimension, arrive in their world. His attempt to thin out humanity so mutants can thrive backfires, as the virus infects both superhumans and mutants, threatening to consume the planet in record time. Magneto parlays with the X-Men and later joins the remaining superhero forces in their battles with the growing ranks of the infected. But while the threat may be Magneto's fault, his self-sacrifice and caring attitude show that it's his mission, not his inherent nature, that has made him a villain in the past.
Magneto’s self-sacrifice ends in his violent consumption in Marvel Zombies #1, but his efforts to safeguard the last of humanity show that his monstrous excesses are all in the name of preserving mutantkind. Robbed of that larger goal - or with other ways to pursue it, as he currently has on Earth-616's Krakoa - the Marvel Zombies proved that Magneto has the heart of a hero.