Leotard Devil (ハイグレ魔王, Haigure Maou) is a character that appears in Crayon Shin-chan: Action Mask vs. Leotard Devil.

He is an alien from another dimension who attempts to invade Earth.

Leotard Devil tries to change all the earth peoples into high-leg humans who put on high-leg cut leotard. He is concealing his appearance usually putting on the mask and the mantle. He wears a leotard with red high leg cut with his mohican head. He looks like a beautiful woman who has a light blue skin while he is actually a man dressed up as a woman. He attacks by electric shock, the phylactic power is also high. He is of homosexual orientation.

He has four main servants: Baron Thong and the three Stomach Band Ladies. He also has a whole army of simple henchmen.