Maybe Voldemort somehow discovers the existence of the world of The Walking Dead and decides to use the undead there as his army. He sends some of his Death Eaters through a magically created gateway. However, things don't go as planned as the walkers are not as easy to control as he thought. Meanwhile, Rick and his group from The Walking Dead encounter some Hogwarts students who were sent to study the strange new world. Together, they must find a way to stop Voldemort's plan and close the gateway between the two worlds.
One possible plot could be that a powerful dark magic spell goes wrong in the Harry Potter world and creates a portal to the world of The Walking Dead. Harry, Hermione, and Ron find themselves in this post - apocalyptic world filled with walkers. They have to use their magic skills to survive, like using the Stunning Spell to immobilize walkers and the Fire - Making Charm to keep the walkers at bay at night. Meanwhile, some of the survivors from The Walking Dead world are in awe of their magic and start to learn from them, creating a unique bond between the two groups.
One possible plot could be that a spell gone wrong in the wizarding world accidentally opens a portal to the world of The Walking Dead. Harry Potter and his friends find themselves in this post - apocalyptic world. They use their magic to fight off the walkers, but also face moral dilemmas as they interact with the survivors who have no concept of magic. Hermione might try to find a scientific explanation for the walkers while Ron is more focused on survival and getting back home.
One possible plot could be that Voldemort uses the dark magic to create a plague similar to the one in The Walking Dead. The wizards and witches have to not only fight against the undead but also Voldemort's forces. Harry and his friends would need to find a way to stop the spread of the plague and defeat Voldemort once and for all, while also learning how to survive in a world filled with the walking dead.
One possible plot could be that Zoey, who might be a survivor with unique skills like being an excellent tracker. She could cross paths with the main group from The Walking Dead. Maybe she has a cure or a lead on a safe haven that she's trying to reach. Along the way, she has to deal with the same undead threats and the complex human relationships that are characteristic of The Walking Dead world.
One possible plot could be that Batman finds himself in the world of The Walking Dead. He uses his detective skills to figure out the origin of the zombie outbreak. Maybe he teams up with some of the survivors like Rick. He'd use his gadgets to defend against the walkers. For example, his batarangs could be used to take out walkers from a distance.
One possible plot could be that the zombies from The Walking Dead somehow end up in the Naruto world. Naruto and his friends have to use their ninja skills to fight off the hordes of zombies. Maybe they could also try to find a cure using their knowledge of chakra and medical ninjutsu.
One possible plot could be that Inuyasha and his friends are somehow transported to the world of The Walking Dead. Inuyasha's sword, Tessaiga, could be effective against the zombies as it can cut through almost anything. They could team up with the survivors in the Walking Dead world. Kagome's spiritual powers might also be useful in detecting the zombies from a distance or even purifying them in some way.
Perhaps Voldemort somehow manages to bring the Left 4 Dead zombies into the wizarding world. The Order of the Phoenix and the Death Eaters are forced to team up to survive. The Death Eaters' dark magic might be used in new and unexpected ways against the zombies, and the Order's more defensive and protective spells would also be crucial. Harry, being the hero, could figure out a way to stop Voldemort from bringing in more zombies and find a way to send the existing ones back.
One possibility could be that the dark magic in the Harry Potter world somehow creates a zombie - like plague similar to the one in The Walking Dead. Harry and his friends then have to use their magic skills not only to fight the dark wizards but also to survive the hordes of the undead. They might create magical barriers to keep the zombies out of Hogwarts.
Maybe the main characters of both shows meet in a post - apocalyptic city. The more science - minded characters from 'Z Nation' try to study the walkers from 'The Walking Dead' to see if there are differences in the virus strains. This leads to a series of adventures as they protect each other from zombie attacks during the research.
One possible plot could be that Naruto and his friends somehow end up in the world of The Walking Dead. Naruto's ninja skills would be really useful in fighting off the zombies. He could use his shadow clone jutsu to create distractions while they look for supplies or a safe place. His friends like Sakura could use her medical skills to treat any survivors they come across. And Sasuke could use his sharingan to detect any hidden threats, either from the zombies or from other groups of survivors.