From Wikipedia, Kaiju (Japanese: 怪獣, Hepburn: Kaijū, lit. 'Strange Beast') is a Japanese genre of films and television featuring giant monsters. The term kaiju can refer to the giant monsters themselves, which are usually depicted attacking major cities and engaging the military, or other kaiju, in battle. The kaiju genre is a subgenre of tokusatsu (特撮, "special filming") entertainment.
Examples of famous Kaiju include Godzilla, Gamera, Daimajin etc.