Godzilla movie from
1965.
Japanese title:
Kaiju Daisenso.
Two astronauts journey to the newly discovered and creatively-named Planet X, where they are met by the planet's Devo-esque inhabitants. Their leader, a sinister fellow known as "The Controller" tells them that his people are constantly threatened with annihilation by the flying three-headed space monster King Ghidorah. He proposes a bargain: if the people of Earth will allow them to capture Godzilla and Rodan and bring them to Planet X to fight King Ghidorah, the X-ers will provide Earth with a data tape containing advanced medical knowledge.
This is all, of course, a dirty Commie trick. After the exchange is made, the Earth people play the tape only to discover that it contains an ultimatum: the X-ists have placed all three monsters under their control, and unless Earth surrenders, they will unleash the titanic beasts on us.
But their plot is foiled when a winsome alien lass who pines for one of the astronauts sacrifices her life to give us the secret of the aliens' weakness -- a certain sound that drives them mad. (I wonder what our weakness would be? If the situation was reversed, would a hastily scrawled note revealing that we drown when immersed in water tip the scales of battle?) After the aliens have been neutralized, their grip on the monsters is broken with an "A-Cycle Light Ray". The freed Godzilla and Rodan proceed to open up a can of whoop ass on Ghidorah; the trio falls into the ocean and the defeated Ghidorah flees in shame.
I wish my name was "The Controller".