Brainiac (May 29, 1958) This Day In Comics
Brainiac is a bald, green-skinned humanoid who arrived on Earthand shrank various cities, including Metropolis, storing them in bottles with the intent of using them to restore the then-unnamed planet he ruled. He is originally notable only for his having shrunk the bottle city of Kandor, for having a shrinking ray, and for using a force-shield. Kandor was once the capital of Krypton until it was shrunken and stolen by Brainiac, several years before the planet was destroyed. Superman discovered the city in Brainiac’s possession when the android came to Earth decades later to harvest more cities.
Brainiac’s appearance in “Superman’s Return to Krypton” displays how the villain stole the bottle city of Kandor, which is ironically and tragically the only city on Krypton that believes Jor-El’s warning of doom for the planet, and had already built a space-ark within the city to save the population. Superman rescued Kandor, keeping it in his Fortress of Solitude while looking for a way to restore it to full size. It is later revealed the city had six million inhabitants when stolen. Superman was able to restore the population to normal size and they settled on another planet that revolved around a red sun. Brainiac reappears later planning to defeat Superman by exposing him to both Red and Green Kryptonite, giving Superman a third eye on the back of his head, forcing him to wear various hats to hide it. Superman soon defeats Brainiac and sends him off into the distant past.
This is the first in-story appearance of Brainiac’s iconic red diodes atop his head, which had previously appeared on the cover of his first appearance in Action Comics #242 (May 29, 1958) which was also the issue which included the first appearance of Kandor.