Anguirus is a fictional monster, or kaiju, which first appeared in Godzilla Raids Again (1955), the second film in the Godzilla franchise. Anguirus is the first monster to be shown engaging in combat with Godzilla in a film. Since then, the character has appeared conversely as an enemy and an ally of Godzilla in numerous films produced by Toho, including Destroy All Monsters, Godzilla vs. Gigan, Godzilla vs. Megalon, Godzilla vs. Mechagodzilla, and Godzilla: Final Wars. He has also appeared in other media, including comic books and video games.

Kaiju is a Japanese term that is commonly associated with media involving giant monsters. A subgenre of science fiction, it was created by Eiji Tsuburaya and Ishirō Honda. The term can also refer to the giant monsters themselves, which are usually depicted attacking major cities and battling either the military or other monsters.