King Ghidorah
The origins of Megalon can be traced back to 1969's "All Monsters Attack", as the original working idea for the film's antagonist Gabara was initially envisioned as a giant mole cricket called Gebara. The character was later reworked into Kaoru Mabuchi's 1971 treatment for "Godzilla vs. the Space Monsters: Earth Defense Directive", a precursor to 1972's "Godzilla vs. Gigan". The proposal called for Megalon to be paired with Gigan and King Ghidorah under the command of the hostile alien invader Miko, only to be defeated and driven off by the combined might of Godzilla, Anguirus, and a brand new monster called Majin Tuol. The next draft of the script, titled "The Return of King Ghidorah!", retained the core villain cast of Gigan, King Ghidorah, and Megalon, but replaced Anguirus and Majin Tuol with Varan and Rodan. However, most of the proposed monsters were cut, leading to the final version of "Godzilla vs. Gigan".