Uranians

Uranus' inhabitants are actually small mechanical robots. Their civilization is quite advanced, they can tour the solar system in circular space ships and although having weapons like 'lance throwers' and 'flame cannons', they have other advanced technologies like 'transporta-rays' (which transport things and animals) and an interplanetary zoo.

In September 1949, based on a "Children's Picture Book of Animals", they tried catching an animal from each page, including a human man and woman. Superman deceives them into thinking all humans were robots, which they had no interest in (WF No. 6, Sep 1949: "The Alphabetical Animal Adventure").