Batman and Robin face off against aliens for the first, but not the last, time in Batman 41 (June/July 1947).
Finger and Mooney spin another Penguin tale that is fairly simple and basic, but looks good.
The Penguin opens a bird store, and gives away free birds to prominent people, which makes Batman suspicious. And, indeed, he has rigged the cages with explosives, and uses them for his crimes.
Still, there are a number of fun action scenes.
Gardner Fox joins Mooney for the cover story, which will see Batman and Robin head to Mars.
An alien approaches Bruce Wayne on the street, revealing his own nature, and that he has come to Earth to bring Batman and Robin to his planet to stop a criminal, Sax Gola, who has proved beyond the aliens ability to stop.
The story is played very straight, and the aliens and their world look far better than they would in later interplanetary outings. Not a bad story in and of itself, only a scary hint of what was to come.