M Space Hunter Nebula Aliens

Godzilla vs. Gigan (1972) had the aliens from an Earth-like planet in the M Space Hunter Nebula (M宇宙ハンター星雲人, M Uchuu Hantā Seiunjin?, M Space Hunter Nebula People) (also known as Nebula M Space Hunter, Space Hunter Galaxy M) invade Earth in order to escape their own dying planet, long plagued by pollution caused by its previous (and now long extinct) inhabitants, a species just like humans. Using "action signal tapes" to control Gigan and King Ghidorah, the aliens had the two monsters demolish Tokyo until they were challenged by Godzilla and Anguirus.

They were headquartered in a large Godzilla-shaped structure called the Godzilla Tower. The Tower was capable of firing lethal laser beams from its mouth, and these beams very nearly killed Godzilla until the Tower was destroyed by explosives smuggled into the head section, freeing Gigan and Ghidorah in the process. The aliens called their human guises "uniforms," and could only use previously deceased humans for them.

When their uniforms were killed (or perhaps simply sustained enough damage), the aliens' disguises dissolve, revealing their true forms: massive, human-sized cockroaches. With the exception of the Godzilla Tower, the aliens possessed nothing impressive, and after their initial invasion, were never heard from again, except to send Gigan to assist Megalon in Godzilla vs. Megalon (1973).