A zombie film is a film genre. Zombies are fictional creatures usually portrayed as reanimated corpses or virally infected human beings. They are commonly portrayed as cannibalistic in nature. While zombie films generally fall into the horror genre, some cross over into other genres, such as action, comedy, science fiction, thriller, or romance. Distinct subgenres have evolved, such as the "zombie comedy" or the "zombie apocalypse". Zombies are distinct from ghosts, ghouls, mummies, Frankenstein's monsters or vampires, so this article does not include films devoted to these types of undead.