Martian (Tom and Jerry)

The Martians are a sapient species of tiny green humanoids. They eat foods that humans (and mice) find unappetizing.

Culture and society
Their society is ruled by a king.

History
The first to make contact with them is Jerry Mouse, after he landed on Mars and was greeted by Peep. They later took him in, believing him to be a god.

Biology
They are tiny green-skinned creatures, matching the description of the archetypical "little green man" that was popular in science fiction during the 1950's.