Invasion of Planet X was released in the year 1965。Invasion of Planet X is also called as Kaijû daisenso, Invasion of the Astros, Invasion of the Astro-Monsters, Invasion of Astro-Monster, Godzilla vs. Monster Zero, Befehl aus dem Dunkel, Battle of the Astros, Avaruushirviöt hyökkäävät。

Aliens from the mysterious Planet X, which resides on the dark side of of Jupiter, come to Earth asking its people to help them save their world from the dreaded King Ghidrah by letting them "borrow" Godzilla and Rodan. The aliens are actually planning to use the three monsters to take over our planet.