Max (called "Moon-Cat" by the penguins) is a stray tabby cat that lives on the top of a building in New York. He is gold colored with one blue eye and one green eye. He has no fur on the tip of his tail. Originally wanted to eat the penguins after they crashed on his roof, but had a change of heart after they gave him a can of sardines as a parting gift.
He appears once more in "Street Smarts" where he helps the penguins retrieve Mort from Elmer by teaching them how to be a dog. In the end, Max and Elmer become close friends, but only because Elmer thinks Max is a lemur.