Aliens arrive in the Godzilla franchise during 1965’s imaginative and spectacular Monster Zero, also known as Invasion of Astro-Monster.
And when Godzilla and Rodan are apprehended by alien saucers for example, the huge monsters are trapped inside transparent force-field bubbles, and carried away to the stars. The effects work for this and other sequences hold up beautifully, even today. In short, the visuals of Monster Zero are often breathtaking.
When the two human astronauts leave Planet X and the captured monsters behind, Godzilla and Rodan actually look to be worried -- at least to me -- like they don’t want to be left there, so far away from their homes.
This is one quality that I love from the Showa Era: there’s a sympathy and understanding for these monsters in these early films. They are not just mindless creatures, but beings with personality and identity.
After he and Rodan send Ghidorah off packing on Planet X, Godzilla leaps into the air, crosses his legs, and alternates flipping his hands across his head and at shoulder level.
This is one of the weirdest things you could imagine seeing Godzilla do…and yet, his exuberance makes sense given that King Ghidorah is "the demon of the galaxy" and one tough opponent.