Godzilla vs. Mechagodzilla
The film "Godzilla vs. Megalon" introduced the Seatopians during the space alien-themed 1970s (see 1972's "Godzilla vs. Gigan" and 1974's "Godzilla vs. Mechagodzilla"). Though human and not extraterrestrial, their shadowed origins, alliance with the Nebulans, and apparent goal of world conquest are more in keeping with the several alien races from the Godzilla films than with the usual diplomatic roles assigned to fictional countries.