Godzilla ( ɡod-ZIL-ə) is a fictional monster, or kaiju, that debuted in the eponymous 1954 film, directed and co-written by Ishirō Honda. The character has since become an international pop culture icon, appearing in various media: 33 Japanese films produced by Toho Co., Ltd., five American films, and numerous video games, novels, comic books, and television shows. Godzilla has been dubbed the King of the Monsters, an epithet first used in Godzilla, King of the Monsters! (1956), the American localization of the 1954 film.

Originally and in most iterations of the creature, Godzilla is a colossal prehistoric reptilian or dinosaurian monster that is amphibious or resides partially in the ocean, awakened and empowered after many years by exposure to nuclear radiation and nuclear testing. With the nuclear bombings of Hiroshima and Nagasaki and the Lucky Dragon 5 incident still fresh in the Japanese consciousness, Godzilla was conceived as a metaphor for nuclear weapons. Others have suggested that Godzilla is a metaphor for the United States, a "giant beast" woken from its "slumber" that then takes terrible vengeance on Japan. As the film series expanded, some storylines took on less serious undertones, portraying Godzilla as an antihero or lesser threat who defends humanity. Later films address disparate themes and commentary, including Japan's apathy, neglect, and ignorance of its imperial past, natural disasters, and the human condition.

Godzilla has been featured alongside many supporting characters and, over the decades, has faced off against various human opponents, such as the Japan Self-Defense Forces (JSDF), in addition to other gargantuan monsters, including Gigan, King Ghidorah, and Mechagodzilla. Godzilla has fought alongside allies such as Anguirus, Mothra, and Rodan and has had offspring, including Godzilla Junior and Minilla. Godzilla has also battled characters and creatures from other franchises in crossover media —such as King Kong— as well as various Marvel Comics characters, like S.H.I.E.L.D., the Fantastic Four, and the Avengers, as well as DC Comics characters such as the Justice League, the Legion of Doom and the Green Lantern Corps.