DC Zombies is a storyline taking place in an alternate DC Universe. It is an Amalgamation of Marvel Zombies and DC.
Within the DC Multiverse is an alternate Earth, which contains alternate versions of DC superheroes. The story begins as a zombie Captain Marvel crash lands before infecting the Justice League. The infection spreads via contact with the blood of the victim, usually through a bite by an infected individual. The zombie super beings largely retain their intellect and personality, although they are consistently driven by the hunger for fresh meat. Ash Williams of the Evil Dead franchise gets transported to this universe where he attempts to locate the Necronomicon which he believes is the cause of the zombie outbreak. He goes to Vandal Savage who informs Ash that this was not the case. He then commands the 'Necronomicon to reawaken the dead in order to fight the zombies, in an attempt to allow the last surviving humans to escape. At the same time, STAR attempts to find a cure for the virus while simultaneously fighting off the zombies. Batman creates a transporter device that can transfer surviving humans to uninfected alternate worlds. Meanwhile, Mr. Elongated of the Justice League International goes insane due to the death of his children (devoured by a newly-turned Jade), and begins to see the Zombie Virus as a 'higher lifeform.' In his insanity, he infects himself as well as his teammates before passing the virus on to Superman as well. Batman, with the help of Wonder Woman, breaks the transporter so that the zombies cannot use it to infect other alternate universes (because the effects of the virus apparently, partially degrade the intellects of those infected, neither "zombie Dibny" nor "zombie Clark Kent" are able to engineer a replacement portal).
The zombie Superman tricks Clark Kent of the New 52 timeline into entering this reality in order to allow the zombie Justice League passage into the New 52 reality. After rescuing Flash, the Justice League follow him into the zombie realm and save other surviving humans, while Psimon remains behind to destroy the transporter. Psimon eventually learns that Cyborg is still alive. However, before he can reach him, he is killed and eaten (but not before beheading Green Arrow). Kalikak arrives on Earth and informs the zombies that his master Darkseid is en route to conquer the planet. The zombies attack Kalibak, who is overpowered and devoured by several of the former heroes: Aquaman, Superman, Hawkman, Flash, Martian Manhunter, Green Lantern, and Wildcat. After acquiring a portion of Kalibak's strength, they slaughter what they believe to be the rest of the zombies.
Psimon's henchmen return to Earth to find Psimon, but instead discover a still-living Atom. The Atom has escaped from the lab of the zombie Hawkman, who has been keeping him alive as a food source. As a result of several feedings, the Atom is now missing an arm and a foot. As well as the Atom, zombie Hawkgirl got into another argument with her husband when she discovered that Hawkman was hoarding the Atom for food and is decapitated, although her head remains sentient. After observing Hawkgirl's head begging for flesh, he reasons that the hunger is more psychological than physical.
Darkseid then arrives on Earth and is attacked by the zombies, but he repels them easily. Hawkman, Superman, and Hal Jordan, Flash, and Wildcat create a device that amplifies the powers they gained from Kalibak, and together they are able to injure Darkseid. The omega-powered zombies fight off zombified versions of several supervillains and then proceed to devour Darkseid. Hawkman, Green Lantern, Superman, Martian Manhunter, Flash, and Wildcat are then infused with Darkseid's power, becoming the collective Darksi. At the same time this is occurring, the New 52 version of Bruce Wayne seeks a cure to the infected Justice League International who had earlier crossed over to the New 52 universe from the Zombiverse. The zombies escape and are defeated by New 52 Vandal Savage, es of the New 52 Secret Society, Savage regains his body. New 52 Savage goes back into his body after Bruce takes care of the zombie version of himself, and traps himself in the Zombie Universe because of the Zvilpogghua inside him, which goes into the most powerful being in the room. He then engages in confrontation with the Zombie Darksi. While the Darksi went into interstellar space for more food, those zombies that were not killed by the Darksi came out of hiding.
In the main DC Universe, Zombie Daethstroke (later known as Headstroke) shows up from the Nexus of all reality, and infects some metahumans that he encounters. A task force is sent to investigate the problem but most of them get eaten. Dracula wants to find a cure and so Red Tornado sets out to find blood from a human on Zombie Earth. After taking some from Jokers's still-living wife, Red Tornado kills some of the zombies. He then finds out that zombie Dracula has abducted his Post-Crisis counterpart and is trying to get every superhero into one room so he can infect as many as possible so they can ravage Post Crisis in its turn. Red Tornado returns to the main universe, and kills all the zombies, apart from the head of zombie Deadpool and Simon Garth.
Post-Crisis's Dracula forms a new group of Midnight Sons and sets off to find zombie Deathstroke and Simon. After fighting off zombies, they go and set off to find Black Talon who has Deathstroke. The vaccine Dracula made changed the zombie virus into an airborne strain, and also turned Jack Russell into a zombie. Jennifer Kale asked help from Mammon, who used her to try to take over the storm. Hellfire then got Mammon out of Kale's body, and Kale and Black Talon cage the zombie virus into the body of Simon, who seems to have killed zombie Deathstroke, which we find out is not true in Deathstroke.. And in DC Zombies 5, Dracula sends Red Tornado and the Ambush Bug into other worlds to find a cure to the zombie virus.
Five years later, Cyborg, the Atom and Hawkgirl return to the Zombiverse. The Atom and Hawkgirl are now equipped with new cybernetic limbs and Hawkgirl is also lucid once more. They find nothing but plant life as the Darksi zombies have long since departed. After a while, they found New Ivy Town, and settle for a while. On the edge of the known universe, several decades later, the Darksi plan to go back to earth and fix Clark Kent's original transporter device. When they get there, however, they discover that the human race is not yet totally extinct. Atom was turned into a zombie when someone tried to kill him, and Hawkgirl turned him. The zombies started to fight, because they knew that the hunger was fading; at the end of the book the Hunger has faded completely, and one of the Ivyans sends the zombies into a third alternate world (Earth Z).
On Earth Z, the DC Zombies lose their Darksi abilities and begin to suffer from the Hunger again, ravaging this world in its turn, while Hawkman plans to spread zombies to every alternate universe. The people who wanted to destroy the zombies formed the New Justice League,and dose Clayface with the vaccine from Dracula and Superman's nanobots. Under the influence of the nanobots, Clayface killed the remaining zombies, but Captain Marvel was thrown back in time and across universes by Pandora which created a time loop as this is the Captain Marvel that started the original zombie outbreak on this earth.