As far as typical mythology surrounding these creatures go, not much at all would happen. These three creatures have no reason to eat one another, mostly because it would benefit them in no way, for what defines them through their characteristics.
A zombie feasts only on the flesh of the living. This is a known rule. It would probably register the vampire as an object rather than a meal. Either way the vampire is undead, and cannot sustain the zombie.
Let’s also remember that the vampire is much stronger than the zombie, and even if, for some reason, a zombie attacked him, the vampire would destroy it. In some stories, it’s also not uncommon for a vampire to control zombies.
The zombie may attack the werewolf, however, it’s extremely rare to see a zombie eat the flesh of an animal. Some sources, such as Night of the Living Dead show that through limited curiosity and/or desperation, a zombie may consume something like a rodent, and find it acceptable. They may even consume the flesh of the dead, but this will not help them much, unless it’s a fresh corpse. But ultimately, zombies want humans.
Technically, a werewolf is a human infected by lycanthrope, but this human will take all the characteristics of the Canidae family, as he turns into a super demon wolf thing. The zombie will not register this as food. (but unlike how the zombie processes the presence of the vampire, the zombie may detect the werewolf as something that is, indeed, alive) And as with the vampire, should the zombie attack the werewolf, it will get its ass kicked.
However, here we get to an interesting turn of events. I’m unsure if a zombie may be able to affect an animal. I’m thinking it might be able to, at least most mammals.
Resident Evil has zombie dogs, although those were all infected directly by the virus, rather than having the virus ported by another infected being, or at least infected by other zombie dogs; now I’m all curious about variant zombie infection levels when it comes to different species.
If this is the case, we would have to know precisely which is stronger, a zombie curse or virus, or lycanthrope. Which one would cancel which one out? Well, lycanthrope, as far as I know, needs a live body to do its thing. It’s based off of rabies, and therefore needs a live system to be able to infect the host. If a zombie bites a werewolf, or the human infected with lycanthrope when it’s in human form, I’m thinking that the zombie virus or curse would not be affected by the lycanthrope, since its job is to destroy the entire system, no matter its state. One zombie bite results in zombification in about three days, when it comes to classic shuffling zombies. The lycanthrope may run its course and become inactive or inefficient, having a severely affected system to work with. It will die away once the human dies and becomes a zombie.
But that’s so boring. What I wouldn’t give to see some hyper badass zombie werewolf.
A vampire is widely based upon symbolism rather than biology and science. (Angel is bullshit) That it needs the blood of the living to sustain itself is drawn upon inner human musings, emotional catastrophe and heresy. Be that as it may, much like the zombie, the vampire needs the blood of a living human being, preferably a young maiden in older stories. Zombies are definitely out.
But if a vampire did bite a zombie, would it turn into some vampire zombie? While that would rock, chances are, no. This argument may need to address the many ways that vampires turn humans. Sometimes the bite alone is contagious, sometimes the victim will only turn if the vampire decides it wants this human to turn, and other times, a ritual needs to be performed for the turning to occur. The zombie cannot turn.
A zombie is no longer a human, and cannot reap the effects of the vampire’s bite. It won’t work because the zombie no longer has its soul, and this is needed to corrupt the human into the ranks of darkness. (science VS spirituality)
This may be argued however, since classic zombies are sometimes known to retain their humanity. Bub from Day of the Dead is a great example, as are the curious zombies who learn to use tools, open doors and whatnot, although this learning experience has its big limits, keeping the skill in a very primitive level. Still, the curse of the vampire doesn’t obey to the human brain and its science, (the latter much emphasized upon in most zombie scenarios) so I theorize that it won’t work, especially since zombies found in more spiritual and fantasy like settings are even more brainless monsters than ones found in modern settings.
Vampires may sustain themselves with animal blood, but this is not nearly enough at all, and they will have to seek out a human eventually. When a man affected by lycanthrope turns into a werewolf, he is no longer a human. The vampire may not be able to use its blood. However, in dire situations, the vampire may attack the werewolf and drink its blood, and that it’s blood from a werewolf is probably much more satisfying than the blood of a normal animal.
However I stress my point, a vampire needs the blood of a human.
But what would happen to the werewolf if a vampire transferred its curse to it? Well, zombie viruses and lycanthrope may be debated in strength, but the curse of the vampire is damnation itself, and the banishment of God. It is the strongest curse of all.
The werewolf will turn into a vampire. But as lycanthrope needs a living system to work, sadly, we won’t have a vampire werewolf, not traditionally anyways. The disease will die away.
However, this vampire, formerly a werewolf, will most likely have some superior shape shifting qualities, especially, of course, when it comes to turning into a wolf. Much more so than other vampires.
The werewolf itself is extremely reminiscent of the characteristics which define the zombie and the vampire. Its difference lies in that it’s alive. A human affected with lycanthrope will have severe cravings for red meat, the bloodier the better. They may wolf down raw steak and things.
This should tell you what the werewolf requires; live, bloody meat. It has no interest in vampires or zombies, who are undead. However, it’s not as passive or as indifferent as the zombie or the vampire. Like the zombie, the werewolf is not conscious of its actions in wolf form, and acts upon raw instinct. It will attack absolutely anything that moves, whether it can eat it or not. If it attacks a vampire however, its chances of victory are nearly non existent. And again, while lycanthrope is contagious through biting, the vampire and the zombie are undead, and will not be affected. And even so…most things that a werewolf attacks and walks away victorious from are left in shreds and pieces. The disease couldn’t take effect even if the victim was applicable for it.
Keep in mind I’m speaking strictly tradition wise here. Exceptions exist, such as UV ray infused bullets to fight werewolves with and zombies attacking sharks…
Also, BEHOLD MY NO LIFE HAVING. ...word game.