kaijin

A relatively broad term in Japanese encompassing any fictional human-like character that possesses supernatural abilities (literally meaning "mysterious person"), usually used to refer to villains. Related to kaiju, insofar as possessing monstrous traits or abilities, albeit usually human-sized and humanoid in appearance. Examples in Japan include the titular characters from Toho's Transforming Human Series films (The H-Man, The Secret of the Telegian and The Human Vapor), Godman, and many characters in the Kamen Rider franchise (including some of the Riders themselves), while Western examples include Frankenstein's Monster.

On Danbooru, per the broad definition, kaijin can be depicted in various fashions: monster boy/monster girl, cyborg, alien, etc. Use the appropriate tag for the specific kaijin.