Kaiju No. 8 , also known in English as Monster #8, is a Japanese manga series written and illustrated by Naoya Matsumoto. It has been serialized on Shueisha's Shōnen Jump+ app and website since July 2020, with its chapters collected in 12 tankōbon volumes as of April 2024. Viz Media has licensed the series for English release in North America.

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.